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3780 lines
146 KiB
Plaintext
\input texinfo
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@setfilename gdbint.info
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@include gdb-cfg.texi
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@ifinfo
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@format
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START-INFO-DIR-ENTRY
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* Gdb-Internals: (gdbint). The GNU debugger's internals.
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END-INFO-DIR-ENTRY
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@end format
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@end ifinfo
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@ifinfo
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This file documents the internals of the GNU debugger @value{GDBN}.
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Copyright 1990-1999 Free Software Foundation, Inc.
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Contributed by Cygnus Solutions. Written by John Gilmore.
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Second Edition by Stan Shebs.
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Permission is granted to make and distribute verbatim copies of this
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manual provided the copyright notice and this permission notice are
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preserved on all copies.
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@ignore
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Permission is granted to process this file through Tex and print the
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results, provided the printed document carries copying permission notice
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identical to this one except for the removal of this paragraph (this
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paragraph not being relevant to the printed manual).
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@end ignore
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Permission is granted to copy or distribute modified versions of this
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manual under the terms of the GPL (for which purpose this text may be
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regarded as a program in the language TeX).
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@end ifinfo
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@setchapternewpage off
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@settitle @value{GDBN} Internals
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@syncodeindex fn cp
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@syncodeindex vr cp
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@titlepage
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@title @value{GDBN} Internals
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@subtitle{A guide to the internals of the GNU debugger}
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@author John Gilmore
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@author Cygnus Solutions
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@author Second Edition:
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@author Stan Shebs
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@author Cygnus Solutions
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@page
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@tex
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\def\$#1${{#1}} % Kluge: collect RCS revision info without $...$
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\xdef\manvers{\$Revision$} % For use in headers, footers too
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{\parskip=0pt
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\hfill Cygnus Solutions\par
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\hfill \manvers\par
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\hfill \TeX{}info \texinfoversion\par
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}
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@end tex
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@vskip 0pt plus 1filll
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Copyright @copyright{} 1990-1999 Free Software Foundation, Inc.
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Permission is granted to make and distribute verbatim copies of
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this manual provided the copyright notice and this permission notice
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are preserved on all copies.
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@end titlepage
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@c TeX can handle the contents at the start but makeinfo 3.12 can not
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@iftex
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@contents
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@end iftex
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@node Top
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@c Perhaps this should be the title of the document (but only for info,
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@c not for TeX). Existing GNU manuals seem inconsistent on this point.
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@top Scope of this Document
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This document documents the internals of the GNU debugger, @value{GDBN}. It
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includes description of @value{GDBN}'s key algorithms and operations, as well
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as the mechanisms that adapt @value{GDBN} to specific hosts and targets.
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@menu
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* Requirements::
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* Overall Structure::
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* Algorithms::
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* User Interface::
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* Symbol Handling::
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* Language Support::
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* Host Definition::
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* Target Architecture Definition::
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* Target Vector Definition::
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* Native Debugging::
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* Support Libraries::
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* Coding::
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* Porting GDB::
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* Testsuite::
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* Hints::
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* Index::
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@end menu
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@node Requirements
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@chapter Requirements
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@cindex requirements for @value{GDBN}
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Before diving into the internals, you should understand the formal
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requirements and other expectations for @value{GDBN}. Although some
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of these may seem obvious, there have been proposals for @value{GDBN}
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that have run counter to these requirements.
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First of all, @value{GDBN} is a debugger. It's not designed to be a
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front panel for embedded systems. It's not a text editor. It's not a
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shell. It's not a programming environment.
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@value{GDBN} is an interactive tool. Although a batch mode is
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available, @value{GDBN}'s primary role is to interact with a human
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programmer.
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@value{GDBN} should be responsive to the user. A programmer hot on
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the trail of a nasty bug, and operating under a looming deadline, is
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going to be very impatient of everything, including the response time
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to debugger commands.
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@value{GDBN} should be relatively permissive, such as for expressions.
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While the compiler should be picky (or have the option to be made
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picky), since source code lives for a long time usuazlly, the
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programmer doing debugging shouldn't be spending time figuring out to
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mollify the debugger.
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@value{GDBN} will be called upon to deal with really large programs.
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Executable sizes of 50 to 100 megabytes occur regularly, and we've
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heard reports of programs approaching 1 gigabyte in size.
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@value{GDBN} should be able to run everywhere. No other debugger is
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available for even half as many configurations as @value{GDBN}
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supports.
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@node Overall Structure
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@chapter Overall Structure
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@value{GDBN} consists of three major subsystems: user interface,
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symbol handling (the @dfn{symbol side}), and target system handling (the
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@dfn{target side}).
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The user interface consists of several actual interfaces, plus
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supporting code.
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The symbol side consists of object file readers, debugging info
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interpreters, symbol table management, source language expression
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parsing, type and value printing.
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The target side consists of execution control, stack frame analysis, and
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physical target manipulation.
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The target side/symbol side division is not formal, and there are a
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number of exceptions. For instance, core file support involves symbolic
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elements (the basic core file reader is in BFD) and target elements (it
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supplies the contents of memory and the values of registers). Instead,
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this division is useful for understanding how the minor subsystems
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should fit together.
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@section The Symbol Side
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The symbolic side of @value{GDBN} can be thought of as ``everything
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you can do in @value{GDBN} without having a live program running''.
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For instance, you can look at the types of variables, and evaluate
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many kinds of expressions.
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@section The Target Side
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The target side of @value{GDBN} is the ``bits and bytes manipulator''.
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Although it may make reference to symbolic info here and there, most
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of the target side will run with only a stripped executable
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available---or even no executable at all, in remote debugging cases.
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Operations such as disassembly, stack frame crawls, and register
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display, are able to work with no symbolic info at all. In some cases,
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such as disassembly, @value{GDBN} will use symbolic info to present addresses
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relative to symbols rather than as raw numbers, but it will work either
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way.
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@section Configurations
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@cindex host
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@cindex target
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@dfn{Host} refers to attributes of the system where @value{GDBN} runs.
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@dfn{Target} refers to the system where the program being debugged
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executes. In most cases they are the same machine, in which case a
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third type of @dfn{Native} attributes come into play.
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Defines and include files needed to build on the host are host support.
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Examples are tty support, system defined types, host byte order, host
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float format.
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Defines and information needed to handle the target format are target
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dependent. Examples are the stack frame format, instruction set,
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breakpoint instruction, registers, and how to set up and tear down the stack
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to call a function.
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Information that is only needed when the host and target are the same,
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is native dependent. One example is Unix child process support; if the
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host and target are not the same, doing a fork to start the target
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process is a bad idea. The various macros needed for finding the
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registers in the @code{upage}, running @code{ptrace}, and such are all
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in the native-dependent files.
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Another example of native-dependent code is support for features that
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are really part of the target environment, but which require
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@code{#include} files that are only available on the host system. Core
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file handling and @code{setjmp} handling are two common cases.
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When you want to make @value{GDBN} work ``native'' on a particular machine, you
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have to include all three kinds of information.
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@node Algorithms
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@chapter Algorithms
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@cindex algorithms
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@value{GDBN} uses a number of debugging-specific algorithms. They are
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often not very complicated, but get lost in the thicket of special
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cases and real-world issues. This chapter describes the basic
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algorithms and mentions some of the specific target definitions that
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they use.
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@section Frames
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@cindex frame
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@cindex call stack frame
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A frame is a construct that @value{GDBN} uses to keep track of calling
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and called functions.
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@findex create_new_frame
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@vindex FRAME_FP
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@code{FRAME_FP} in the machine description has no meaning to the
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machine-independent part of @value{GDBN}, except that it is used when
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setting up a new frame from scratch, as follows:
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@example
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create_new_frame (read_register (FP_REGNUM), read_pc ()));
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@end example
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@cindex frame pointer register
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Other than that, all the meaning imparted to @code{FP_REGNUM} is
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imparted by the machine-dependent code. So, @code{FP_REGNUM} can have
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any value that is convenient for the code that creates new frames.
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(@code{create_new_frame} calls @code{INIT_EXTRA_FRAME_INFO} if it is
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defined; that is where you should use the @code{FP_REGNUM} value, if
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your frames are nonstandard.)
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@cindex frame chain
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Given a @value{GDBN} frame, define @code{FRAME_CHAIN} to determine the
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address of the calling function's frame. This will be used to create
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a new @value{GDBN} frame struct, and then @code{INIT_EXTRA_FRAME_INFO}
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and @code{INIT_FRAME_PC} will be called for the new frame.
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@section Breakpoint Handling
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@cindex breakpoints
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In general, a breakpoint is a user-designated location in the program
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where the user wants to regain control if program execution ever reaches
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that location.
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There are two main ways to implement breakpoints; either as ``hardware''
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breakpoints or as ``software'' breakpoints.
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@cindex hardware breakpoints
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@cindex program counter
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Hardware breakpoints are sometimes available as a builtin debugging
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features with some chips. Typically these work by having dedicated
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register into which the breakpoint address may be stored. If the PC
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(shorthand for @dfn{program counter})
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ever matches a value in a breakpoint registers, the CPU raises an
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exception and reports it to @value{GDBN}.
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Another possibility is when an emulator is in use; many emulators
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include circuitry that watches the address lines coming out from the
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processor, and force it to stop if the address matches a breakpoint's
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address.
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A third possibility is that the target already has the ability to do
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breakpoints somehow; for instance, a ROM monitor may do its own
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software breakpoints. So although these are not literally ``hardware
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breakpoints'', from @value{GDBN}'s point of view they work the same;
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@value{GDBN} need not do nothing more than set the breakpoint and wait
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for something to happen.
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Since they depend on hardware resources, hardware breakpoints may be
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limited in number; when the user asks for more, @value{GDBN} will
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start trying to set software breakpoints.
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@cindex software breakpoints
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Software breakpoints require @value{GDBN} to do somewhat more work.
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The basic theory is that @value{GDBN} will replace a program
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instruction with a trap, illegal divide, or some other instruction
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that will cause an exception, and then when it's encountered,
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@value{GDBN} will take the exception and stop the program. When the
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user says to continue, @value{GDBN} will restore the original
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instruction, single-step, re-insert the trap, and continue on.
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Since it literally overwrites the program being tested, the program area
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must be writeable, so this technique won't work on programs in ROM. It
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can also distort the behavior of programs that examine themselves,
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although such a situation would be highly unusual.
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Also, the software breakpoint instruction should be the smallest size of
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instruction, so it doesn't overwrite an instruction that might be a jump
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target, and cause disaster when the program jumps into the middle of the
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breakpoint instruction. (Strictly speaking, the breakpoint must be no
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larger than the smallest interval between instructions that may be jump
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targets; perhaps there is an architecture where only even-numbered
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instructions may jumped to.) Note that it's possible for an instruction
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set not to have any instructions usable for a software breakpoint,
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although in practice only the ARC has failed to define such an
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instruction.
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@findex BREAKPOINT
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The basic definition of the software breakpoint is the macro
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@code{BREAKPOINT}.
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Basic breakpoint object handling is in @file{breakpoint.c}. However,
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much of the interesting breakpoint action is in @file{infrun.c}.
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@section Single Stepping
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@section Signal Handling
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@section Thread Handling
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@section Inferior Function Calls
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@section Longjmp Support
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@cindex @code{longjmp} debugging
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@value{GDBN} has support for figuring out that the target is doing a
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@code{longjmp} and for stopping at the target of the jump, if we are
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stepping. This is done with a few specialized internal breakpoints,
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which are visible in the output of the @samp{maint info breakpoint}
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command.
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@findex GET_LONGJMP_TARGET
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To make this work, you need to define a macro called
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@code{GET_LONGJMP_TARGET}, which will examine the @code{jmp_buf}
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structure and extract the longjmp target address. Since @code{jmp_buf}
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is target specific, you will need to define it in the appropriate
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@file{tm-@var{target}.h} file. Look in @file{tm-sun4os4.h} and
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@file{sparc-tdep.c} for examples of how to do this.
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@node User Interface
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@chapter User Interface
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@value{GDBN} has several user interfaces. Although the command-line interface
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is the most common and most familiar, there are others.
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@section Command Interpreter
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@cindex command interpreter
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The command interpreter in @value{GDBN} is fairly simple. It is designed to
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allow for the set of commands to be augmented dynamically, and also
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has a recursive subcommand capability, where the first argument to
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a command may itself direct a lookup on a different command list.
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For instance, the @samp{set} command just starts a lookup on the
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@code{setlist} command list, while @samp{set thread} recurses
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to the @code{set_thread_cmd_list}.
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@findex add_cmd
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@findex add_com
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To add commands in general, use @code{add_cmd}. @code{add_com} adds to
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the main command list, and should be used for those commands. The usual
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place to add commands is in the @code{_initialize_@var{xyz}} routines at
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the ends of most source files.
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@cindex deprecating commands
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@findex deprecate_cmd
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Before removing commands from the command set it is a good idea to
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deprecate them for some time. Use @code{deprecate_cmd} on commands or
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aliases to set the deprecated flag. @code{deprecate_cmd} takes a
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@code{struct cmd_list_element} as it's first argument. You can use the
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return value from @code{add_com} or @code{add_cmd} to deprecate the
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command immediately after it is created.
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The first time a comamnd is used the user will be warned and offered a
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replacement (if one exists). Note that the replacement string passed to
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@code{deprecate_cmd} should be the full name of the command, i.e. the
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entire string the user should type at the command line.
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@section Console Printing
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@section TUI
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@section libgdb
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@cindex @code{libgdb}
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|
@code{libgdb} was an abortive project of years ago. The theory was to
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provide an API to @value{GDBN}'s functionality.
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|
@node Symbol Handling
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@chapter Symbol Handling
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Symbols are a key part of @value{GDBN}'s operation. Symbols include variables,
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functions, and types.
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@section Symbol Reading
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@cindex symbol reading
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@cindex reading of symbols
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@cindex symbol files
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@value{GDBN} reads symbols from @dfn{symbol files}. The usual symbol
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file is the file containing the program which @value{GDBN} is
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debugging. @value{GDBN} can be directed to use a different file for
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symbols (with the @samp{symbol-file} command), and it can also read
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more symbols via the @samp{add-file} and @samp{load} commands, or while
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reading symbols from shared libraries.
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@findex find_sym_fns
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Symbol files are initially opened by code in @file{symfile.c} using
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the BFD library (@pxref{Support Libraries}). BFD identifies the type
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of the file by examining its header. @code{find_sym_fns} then uses
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this identification to locate a set of symbol-reading functions.
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@findex add_symtab_fns
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|
@cindex @code{sym_fns} structure
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|
@cindex adding a symbol-reading module
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|
Symbol-reading modules identify themselves to @value{GDBN} by calling
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@code{add_symtab_fns} during their module initialization. The argument
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to @code{add_symtab_fns} is a @code{struct sym_fns} which contains the
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name (or name prefix) of the symbol format, the length of the prefix,
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and pointers to four functions. These functions are called at various
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|
times to process symbol files whose identification matches the specified
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prefix.
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The functions supplied by each module are:
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@table @code
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@item @var{xyz}_symfile_init(struct sym_fns *sf)
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@cindex secondary symbol file
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|
Called from @code{symbol_file_add} when we are about to read a new
|
|
symbol file. This function should clean up any internal state (possibly
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|
resulting from half-read previous files, for example) and prepare to
|
|
read a new symbol file. Note that the symbol file which we are reading
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|
might be a new ``main'' symbol file, or might be a secondary symbol file
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|
whose symbols are being added to the existing symbol table.
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|
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|
The argument to @code{@var{xyz}_symfile_init} is a newly allocated
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|
@code{struct sym_fns} whose @code{bfd} field contains the BFD for the
|
|
new symbol file being read. Its @code{private} field has been zeroed,
|
|
and can be modified as desired. Typically, a struct of private
|
|
information will be @code{malloc}'d, and a pointer to it will be placed
|
|
in the @code{private} field.
|
|
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|
There is no result from @code{@var{xyz}_symfile_init}, but it can call
|
|
@code{error} if it detects an unavoidable problem.
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|
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|
@item @var{xyz}_new_init()
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|
Called from @code{symbol_file_add} when discarding existing symbols.
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|
This function needs only handle the symbol-reading module's internal
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|
state; the symbol table data structures visible to the rest of
|
|
@value{GDBN} will be discarded by @code{symbol_file_add}. It has no
|
|
arguments and no result. It may be called after
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|
@code{@var{xyz}_symfile_init}, if a new symbol table is being read, or
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|
may be called alone if all symbols are simply being discarded.
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|
@item @var{xyz}_symfile_read(struct sym_fns *sf, CORE_ADDR addr, int mainline)
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Called from @code{symbol_file_add} to actually read the symbols from a
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|
symbol-file into a set of psymtabs or symtabs.
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|
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|
@code{sf} points to the @code{struct sym_fns} originally passed to
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|
@code{@var{xyz}_sym_init} for possible initialization. @code{addr} is
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|
the offset between the file's specified start address and its true
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|
address in memory. @code{mainline} is 1 if this is the main symbol
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|
table being read, and 0 if a secondary symbol file (e.g. shared library
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|
or dynamically loaded file) is being read.@refill
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|
@end table
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|
|
In addition, if a symbol-reading module creates psymtabs when
|
|
@var{xyz}_symfile_read is called, these psymtabs will contain a pointer
|
|
to a function @code{@var{xyz}_psymtab_to_symtab}, which can be called
|
|
from any point in the @value{GDBN} symbol-handling code.
|
|
|
|
@table @code
|
|
@item @var{xyz}_psymtab_to_symtab (struct partial_symtab *pst)
|
|
|
|
Called from @code{psymtab_to_symtab} (or the @code{PSYMTAB_TO_SYMTAB} macro) if
|
|
the psymtab has not already been read in and had its @code{pst->symtab}
|
|
pointer set. The argument is the psymtab to be fleshed-out into a
|
|
symtab. Upon return, @code{pst->readin} should have been set to 1, and
|
|
@code{pst->symtab} should contain a pointer to the new corresponding symtab, or
|
|
zero if there were no symbols in that part of the symbol file.
|
|
@end table
|
|
|
|
@section Partial Symbol Tables
|
|
|
|
@value{GDBN} has three types of symbol tables:
|
|
|
|
@itemize @bullet
|
|
@cindex full symbol table
|
|
@cindex symtabs
|
|
@item
|
|
Full symbol tables (@dfn{symtabs}). These contain the main
|
|
information about symbols and addresses.
|
|
|
|
@cindex psymtabs
|
|
@item
|
|
Partial symbol tables (@dfn{psymtabs}). These contain enough
|
|
information to know when to read the corresponding part of the full
|
|
symbol table.
|
|
|
|
@cindex minimal symbol table
|
|
@cindex minsymtabs
|
|
@item
|
|
Minimal symbol tables (@dfn{msymtabs}). These contain information
|
|
gleaned from non-debugging symbols.
|
|
@end itemize
|
|
|
|
@cindex partial symbol table
|
|
This section describes partial symbol tables.
|
|
|
|
A psymtab is constructed by doing a very quick pass over an executable
|
|
file's debugging information. Small amounts of information are
|
|
extracted---enough to identify which parts of the symbol table will
|
|
need to be re-read and fully digested later, when the user needs the
|
|
information. The speed of this pass causes @value{GDBN} to start up very
|
|
quickly. Later, as the detailed rereading occurs, it occurs in small
|
|
pieces, at various times, and the delay therefrom is mostly invisible to
|
|
the user.
|
|
@c (@xref{Symbol Reading}.)
|
|
|
|
The symbols that show up in a file's psymtab should be, roughly, those
|
|
visible to the debugger's user when the program is not running code from
|
|
that file. These include external symbols and types, static symbols and
|
|
types, and @code{enum} values declared at file scope.
|
|
|
|
The psymtab also contains the range of instruction addresses that the
|
|
full symbol table would represent.
|
|
|
|
@cindex finding a symbol
|
|
@cindex symbol lookup
|
|
The idea is that there are only two ways for the user (or much of the
|
|
code in the debugger) to reference a symbol:
|
|
|
|
@itemize @bullet
|
|
@findex find_pc_function
|
|
@findex find_pc_line
|
|
@item
|
|
By its address (e.g. execution stops at some address which is inside a
|
|
function in this file). The address will be noticed to be in the
|
|
range of this psymtab, and the full symtab will be read in.
|
|
@code{find_pc_function}, @code{find_pc_line}, and other
|
|
@code{find_pc_@dots{}} functions handle this.
|
|
|
|
@cindex lookup_symbol
|
|
@item
|
|
By its name
|
|
(e.g. the user asks to print a variable, or set a breakpoint on a
|
|
function). Global names and file-scope names will be found in the
|
|
psymtab, which will cause the symtab to be pulled in. Local names will
|
|
have to be qualified by a global name, or a file-scope name, in which
|
|
case we will have already read in the symtab as we evaluated the
|
|
qualifier. Or, a local symbol can be referenced when we are ``in'' a
|
|
local scope, in which case the first case applies. @code{lookup_symbol}
|
|
does most of the work here.
|
|
@end itemize
|
|
|
|
The only reason that psymtabs exist is to cause a symtab to be read in
|
|
at the right moment. Any symbol that can be elided from a psymtab,
|
|
while still causing that to happen, should not appear in it. Since
|
|
psymtabs don't have the idea of scope, you can't put local symbols in
|
|
them anyway. Psymtabs don't have the idea of the type of a symbol,
|
|
either, so types need not appear, unless they will be referenced by
|
|
name.
|
|
|
|
It is a bug for @value{GDBN} to behave one way when only a psymtab has
|
|
been read, and another way if the corresponding symtab has been read
|
|
in. Such bugs are typically caused by a psymtab that does not contain
|
|
all the visible symbols, or which has the wrong instruction address
|
|
ranges.
|
|
|
|
The psymtab for a particular section of a symbol file (objfile) could be
|
|
thrown away after the symtab has been read in. The symtab should always
|
|
be searched before the psymtab, so the psymtab will never be used (in a
|
|
bug-free environment). Currently, psymtabs are allocated on an obstack,
|
|
and all the psymbols themselves are allocated in a pair of large arrays
|
|
on an obstack, so there is little to be gained by trying to free them
|
|
unless you want to do a lot more work.
|
|
|
|
@section Types
|
|
|
|
@unnumberedsubsec Fundamental Types (e.g., @code{FT_VOID}, @code{FT_BOOLEAN}).
|
|
|
|
@cindex fundamental types
|
|
These are the fundamental types that @value{GDBN} uses internally. Fundamental
|
|
types from the various debugging formats (stabs, ELF, etc) are mapped
|
|
into one of these. They are basically a union of all fundamental types
|
|
that @value{GDBN} knows about for all the languages that @value{GDBN}
|
|
knows about.
|
|
|
|
@unnumberedsubsec Type Codes (e.g., @code{TYPE_CODE_PTR}, @code{TYPE_CODE_ARRAY}).
|
|
|
|
@cindex type codes
|
|
Each time @value{GDBN} builds an internal type, it marks it with one
|
|
of these types. The type may be a fundamental type, such as
|
|
@code{TYPE_CODE_INT}, or a derived type, such as @code{TYPE_CODE_PTR}
|
|
which is a pointer to another type. Typically, several @code{FT_*}
|
|
types map to one @code{TYPE_CODE_*} type, and are distinguished by
|
|
other members of the type struct, such as whether the type is signed
|
|
or unsigned, and how many bits it uses.
|
|
|
|
@unnumberedsubsec Builtin Types (e.g., @code{builtin_type_void}, @code{builtin_type_char}).
|
|
|
|
These are instances of type structs that roughly correspond to
|
|
fundamental types and are created as global types for @value{GDBN} to
|
|
use for various ugly historical reasons. We eventually want to
|
|
eliminate these. Note for example that @code{builtin_type_int}
|
|
initialized in @file{gdbtypes.c} is basically the same as a
|
|
@code{TYPE_CODE_INT} type that is initialized in @file{c-lang.c} for
|
|
an @code{FT_INTEGER} fundamental type. The difference is that the
|
|
@code{builtin_type} is not associated with any particular objfile, and
|
|
only one instance exists, while @file{c-lang.c} builds as many
|
|
@code{TYPE_CODE_INT} types as needed, with each one associated with
|
|
some particular objfile.
|
|
|
|
@section Object File Formats
|
|
@cindex object file formats
|
|
|
|
@subsection a.out
|
|
|
|
@cindex @code{a.out} format
|
|
The @code{a.out} format is the original file format for Unix. It
|
|
consists of three sections: @code{text}, @code{data}, and @code{bss},
|
|
which are for program code, initialized data, and uninitialized data,
|
|
respectively.
|
|
|
|
The @code{a.out} format is so simple that it doesn't have any reserved
|
|
place for debugging information. (Hey, the original Unix hackers used
|
|
@samp{adb}, which is a machine-language debugger!) The only debugging
|
|
format for @code{a.out} is stabs, which is encoded as a set of normal
|
|
symbols with distinctive attributes.
|
|
|
|
The basic @code{a.out} reader is in @file{dbxread.c}.
|
|
|
|
@subsection COFF
|
|
|
|
@cindex COFF format
|
|
The COFF format was introduced with System V Release 3 (SVR3) Unix.
|
|
COFF files may have multiple sections, each prefixed by a header. The
|
|
number of sections is limited.
|
|
|
|
The COFF specification includes support for debugging. Although this
|
|
was a step forward, the debugging information was woefully limited. For
|
|
instance, it was not possible to represent code that came from an
|
|
included file.
|
|
|
|
The COFF reader is in @file{coffread.c}.
|
|
|
|
@subsection ECOFF
|
|
|
|
@cindex ECOFF format
|
|
ECOFF is an extended COFF originally introduced for Mips and Alpha
|
|
workstations.
|
|
|
|
The basic ECOFF reader is in @file{mipsread.c}.
|
|
|
|
@subsection XCOFF
|
|
|
|
@cindex XCOFF format
|
|
The IBM RS/6000 running AIX uses an object file format called XCOFF.
|
|
The COFF sections, symbols, and line numbers are used, but debugging
|
|
symbols are @code{dbx}-style stabs whose strings are located in the
|
|
@code{.debug} section (rather than the string table). For more
|
|
information, see @ref{Top,,,stabs,The Stabs Debugging Format}.
|
|
|
|
The shared library scheme has a clean interface for figuring out what
|
|
shared libraries are in use, but the catch is that everything which
|
|
refers to addresses (symbol tables and breakpoints at least) needs to be
|
|
relocated for both shared libraries and the main executable. At least
|
|
using the standard mechanism this can only be done once the program has
|
|
been run (or the core file has been read).
|
|
|
|
@subsection PE
|
|
|
|
@cindex PE-COFF format
|
|
Windows 95 and NT use the PE (@dfn{Portable Executable}) format for their
|
|
executables. PE is basically COFF with additional headers.
|
|
|
|
While BFD includes special PE support, @value{GDBN} needs only the basic
|
|
COFF reader.
|
|
|
|
@subsection ELF
|
|
|
|
@cindex ELF format
|
|
The ELF format came with System V Release 4 (SVR4) Unix. ELF is similar
|
|
to COFF in being organized into a number of sections, but it removes
|
|
many of COFF's limitations.
|
|
|
|
The basic ELF reader is in @file{elfread.c}.
|
|
|
|
@subsection SOM
|
|
|
|
@cindex SOM format
|
|
SOM is HP's object file and debug format (not to be confused with IBM's
|
|
SOM, which is a cross-language ABI).
|
|
|
|
The SOM reader is in @file{hpread.c}.
|
|
|
|
@subsection Other File Formats
|
|
|
|
@cindex Netware Loadable Module format
|
|
Other file formats that have been supported by @value{GDBN} include Netware
|
|
Loadable Modules (@file{nlmread.c}.
|
|
|
|
@section Debugging File Formats
|
|
|
|
This section describes characteristics of debugging information that
|
|
are independent of the object file format.
|
|
|
|
@subsection stabs
|
|
|
|
@cindex stabs debugging info
|
|
@code{stabs} started out as special symbols within the @code{a.out}
|
|
format. Since then, it has been encapsulated into other file
|
|
formats, such as COFF and ELF.
|
|
|
|
While @file{dbxread.c} does some of the basic stab processing,
|
|
including for encapsulated versions, @file{stabsread.c} does
|
|
the real work.
|
|
|
|
@subsection COFF
|
|
|
|
@cindex COFF debugging info
|
|
The basic COFF definition includes debugging information. The level
|
|
of support is minimal and non-extensible, and is not often used.
|
|
|
|
@subsection Mips debug (Third Eye)
|
|
|
|
@cindex ECOFF debugging info
|
|
ECOFF includes a definition of a special debug format.
|
|
|
|
The file @file{mdebugread.c} implements reading for this format.
|
|
|
|
@subsection DWARF 1
|
|
|
|
@cindex DWARF 1 debugging info
|
|
DWARF 1 is a debugging format that was originally designed to be
|
|
used with ELF in SVR4 systems.
|
|
|
|
@c CHILL_PRODUCER
|
|
@c GCC_PRODUCER
|
|
@c GPLUS_PRODUCER
|
|
@c LCC_PRODUCER
|
|
@c If defined, these are the producer strings in a DWARF 1 file. All of
|
|
@c these have reasonable defaults already.
|
|
|
|
The DWARF 1 reader is in @file{dwarfread.c}.
|
|
|
|
@subsection DWARF 2
|
|
|
|
@cindex DWARF 2 debugging info
|
|
DWARF 2 is an improved but incompatible version of DWARF 1.
|
|
|
|
The DWARF 2 reader is in @file{dwarf2read.c}.
|
|
|
|
@subsection SOM
|
|
|
|
@cindex SOM debugging info
|
|
Like COFF, the SOM definition includes debugging information.
|
|
|
|
@section Adding a New Symbol Reader to @value{GDBN}
|
|
|
|
@cindex adding debugging info reader
|
|
If you are using an existing object file format (@code{a.out}, COFF, ELF, etc),
|
|
there is probably little to be done.
|
|
|
|
If you need to add a new object file format, you must first add it to
|
|
BFD. This is beyond the scope of this document.
|
|
|
|
You must then arrange for the BFD code to provide access to the
|
|
debugging symbols. Generally @value{GDBN} will have to call swapping routines
|
|
from BFD and a few other BFD internal routines to locate the debugging
|
|
information. As much as possible, @value{GDBN} should not depend on the BFD
|
|
internal data structures.
|
|
|
|
For some targets (e.g., COFF), there is a special transfer vector used
|
|
to call swapping routines, since the external data structures on various
|
|
platforms have different sizes and layouts. Specialized routines that
|
|
will only ever be implemented by one object file format may be called
|
|
directly. This interface should be described in a file
|
|
@file{bfd/lib@var{xyz}.h}, which is included by @value{GDBN}.
|
|
|
|
|
|
@node Language Support
|
|
|
|
@chapter Language Support
|
|
|
|
@cindex language support
|
|
@value{GDBN}'s language support is mainly driven by the symbol reader,
|
|
although it is possible for the user to set the source language
|
|
manually.
|
|
|
|
@value{GDBN} chooses the source language by looking at the extension
|
|
of the file recorded in the debug info; @file{.c} means C, @file{.f}
|
|
means Fortran, etc. It may also use a special-purpose language
|
|
identifier if the debug format supports it, like with DWARF.
|
|
|
|
@section Adding a Source Language to @value{GDBN}
|
|
|
|
@cindex adding source language
|
|
To add other languages to @value{GDBN}'s expression parser, follow the
|
|
following steps:
|
|
|
|
@table @emph
|
|
@item Create the expression parser.
|
|
|
|
@cindex expression parser
|
|
This should reside in a file @file{@var{lang}-exp.y}. Routines for
|
|
building parsed expressions into a @code{union exp_element} list are in
|
|
@file{parse.c}.
|
|
|
|
@cindex language parser
|
|
Since we can't depend upon everyone having Bison, and YACC produces
|
|
parsers that define a bunch of global names, the following lines
|
|
@strong{must} be included at the top of the YACC parser, to prevent the
|
|
various parsers from defining the same global names:
|
|
|
|
@example
|
|
#define yyparse @var{lang}_parse
|
|
#define yylex @var{lang}_lex
|
|
#define yyerror @var{lang}_error
|
|
#define yylval @var{lang}_lval
|
|
#define yychar @var{lang}_char
|
|
#define yydebug @var{lang}_debug
|
|
#define yypact @var{lang}_pact
|
|
#define yyr1 @var{lang}_r1
|
|
#define yyr2 @var{lang}_r2
|
|
#define yydef @var{lang}_def
|
|
#define yychk @var{lang}_chk
|
|
#define yypgo @var{lang}_pgo
|
|
#define yyact @var{lang}_act
|
|
#define yyexca @var{lang}_exca
|
|
#define yyerrflag @var{lang}_errflag
|
|
#define yynerrs @var{lang}_nerrs
|
|
@end example
|
|
|
|
At the bottom of your parser, define a @code{struct language_defn} and
|
|
initialize it with the right values for your language. Define an
|
|
@code{initialize_@var{lang}} routine and have it call
|
|
@samp{add_language(@var{lang}_language_defn)} to tell the rest of @value{GDBN}
|
|
that your language exists. You'll need some other supporting variables
|
|
and functions, which will be used via pointers from your
|
|
@code{@var{lang}_language_defn}. See the declaration of @code{struct
|
|
language_defn} in @file{language.h}, and the other @file{*-exp.y} files,
|
|
for more information.
|
|
|
|
@item Add any evaluation routines, if necessary
|
|
|
|
@cindex expression evaluation routines
|
|
@findex evaluate_subexp
|
|
@findex prefixify_subexp
|
|
@findex length_of_subexp
|
|
If you need new opcodes (that represent the operations of the language),
|
|
add them to the enumerated type in @file{expression.h}. Add support
|
|
code for these operations in the @code{evaluate_subexp} function
|
|
defined in the file @file{eval.c}. Add cases
|
|
for new opcodes in two functions from @file{parse.c}:
|
|
@code{prefixify_subexp} and @code{length_of_subexp}. These compute
|
|
the number of @code{exp_element}s that a given operation takes up.
|
|
|
|
@item Update some existing code
|
|
|
|
Add an enumerated identifier for your language to the enumerated type
|
|
@code{enum language} in @file{defs.h}.
|
|
|
|
Update the routines in @file{language.c} so your language is included.
|
|
These routines include type predicates and such, which (in some cases)
|
|
are language dependent. If your language does not appear in the switch
|
|
statement, an error is reported.
|
|
|
|
@vindex current_language
|
|
Also included in @file{language.c} is the code that updates the variable
|
|
@code{current_language}, and the routines that translate the
|
|
@code{language_@var{lang}} enumerated identifier into a printable
|
|
string.
|
|
|
|
@findex _initialize_language
|
|
Update the function @code{_initialize_language} to include your
|
|
language. This function picks the default language upon startup, so is
|
|
dependent upon which languages that @value{GDBN} is built for.
|
|
|
|
@findex allocate_symtab
|
|
Update @code{allocate_symtab} in @file{symfile.c} and/or symbol-reading
|
|
code so that the language of each symtab (source file) is set properly.
|
|
This is used to determine the language to use at each stack frame level.
|
|
Currently, the language is set based upon the extension of the source
|
|
file. If the language can be better inferred from the symbol
|
|
information, please set the language of the symtab in the symbol-reading
|
|
code.
|
|
|
|
@findex print_subexp
|
|
@findex op_print_tab
|
|
Add helper code to @code{print_subexp} (in @file{expprint.c}) to handle any new
|
|
expression opcodes you have added to @file{expression.h}. Also, add the
|
|
printed representations of your operators to @code{op_print_tab}.
|
|
|
|
@item Add a place of call
|
|
|
|
@findex parse_exp_1
|
|
Add a call to @code{@var{lang}_parse()} and @code{@var{lang}_error} in
|
|
@code{parse_exp_1} (defined in @file{parse.c}).
|
|
|
|
@item Use macros to trim code
|
|
|
|
@cindex trimming language-dependent code
|
|
The user has the option of building @value{GDBN} for some or all of the
|
|
languages. If the user decides to build @value{GDBN} for the language
|
|
@var{lang}, then every file dependent on @file{language.h} will have the
|
|
macro @code{_LANG_@var{lang}} defined in it. Use @code{#ifdef}s to
|
|
leave out large routines that the user won't need if he or she is not
|
|
using your language.
|
|
|
|
Note that you do not need to do this in your YACC parser, since if @value{GDBN}
|
|
is not build for @var{lang}, then @file{@var{lang}-exp.tab.o} (the
|
|
compiled form of your parser) is not linked into @value{GDBN} at all.
|
|
|
|
See the file @file{configure.in} for how @value{GDBN} is configured
|
|
for different languages.
|
|
|
|
@item Edit @file{Makefile.in}
|
|
|
|
Add dependencies in @file{Makefile.in}. Make sure you update the macro
|
|
variables such as @code{HFILES} and @code{OBJS}, otherwise your code may
|
|
not get linked in, or, worse yet, it may not get @code{tar}red into the
|
|
distribution!
|
|
@end table
|
|
|
|
|
|
@node Host Definition
|
|
|
|
@chapter Host Definition
|
|
|
|
With the advent of Autoconf, it's rarely necessary to have host
|
|
definition machinery anymore.
|
|
|
|
@section Adding a New Host
|
|
|
|
@cindex adding a new host
|
|
@cindex host, adding
|
|
Most of @value{GDBN}'s host configuration support happens via
|
|
Autoconf. New host-specific definitions should be rarely needed.
|
|
@value{GDBN} still uses the host-specific definitions and files listed
|
|
below, but these mostly exist for historical reasons, and should
|
|
eventually disappear.
|
|
|
|
Several files control @value{GDBN}'s configuration for host systems:
|
|
|
|
@table @file
|
|
@vindex XDEPFILES
|
|
@item gdb/config/@var{arch}/@var{xyz}.mh
|
|
Specifies Makefile fragments needed when hosting on machine @var{xyz}.
|
|
In particular, this lists the required machine-dependent object files,
|
|
by defining @samp{XDEPFILES=@dots{}}. Also specifies the header file
|
|
which describes host @var{xyz}, by defining @code{XM_FILE=
|
|
xm-@var{xyz}.h}. You can also define @code{CC}, @code{SYSV_DEFINE},
|
|
@code{XM_CFLAGS}, @code{XM_ADD_FILES}, @code{XM_CLIBS}, @code{XM_CDEPS},
|
|
etc.; see @file{Makefile.in}.
|
|
|
|
@item gdb/config/@var{arch}/xm-@var{xyz}.h
|
|
(@file{xm.h} is a link to this file, created by @code{configure}). Contains C
|
|
macro definitions describing the host system environment, such as byte
|
|
order, host C compiler and library.
|
|
|
|
@item gdb/@var{xyz}-xdep.c
|
|
Contains any miscellaneous C code required for this machine as a host.
|
|
On most machines it doesn't exist at all. If it does exist, put
|
|
@file{@var{xyz}-xdep.o} into the @code{XDEPFILES} line in
|
|
@file{gdb/config/@var{arch}/@var{xyz}.mh}.
|
|
@end table
|
|
|
|
@subheading Generic Host Support Files
|
|
|
|
@cindex generic host support
|
|
There are some ``generic'' versions of routines that can be used by
|
|
various systems. These can be customized in various ways by macros
|
|
defined in your @file{xm-@var{xyz}.h} file. If these routines work for
|
|
the @var{xyz} host, you can just include the generic file's name (with
|
|
@samp{.o}, not @samp{.c}) in @code{XDEPFILES}.
|
|
|
|
Otherwise, if your machine needs custom support routines, you will need
|
|
to write routines that perform the same functions as the generic file.
|
|
Put them into @code{@var{xyz}-xdep.c}, and put @code{@var{xyz}-xdep.o}
|
|
into @code{XDEPFILES}.
|
|
|
|
@table @file
|
|
@cindex remote debugging support
|
|
@cindex serial line support
|
|
@item ser-unix.c
|
|
This contains serial line support for Unix systems. This is always
|
|
included, via the makefile variable @code{SER_HARDWIRE}; override this
|
|
variable in the @file{.mh} file to avoid it.
|
|
|
|
@item ser-go32.c
|
|
This contains serial line support for 32-bit programs running under DOS,
|
|
using the DJGPP (a.k.a.@: GO32) execution environment.
|
|
|
|
@cindex TCP remote support
|
|
@item ser-tcp.c
|
|
This contains generic TCP support using sockets.
|
|
@end table
|
|
|
|
@section Host Conditionals
|
|
|
|
When @value{GDBN} is configured and compiled, various macros are
|
|
defined or left undefined, to control compilation based on the
|
|
attributes of the host system. These macros and their meanings (or if
|
|
the meaning is not documented here, then one of the source files where
|
|
they are used is indicated) are:
|
|
|
|
@ftable @code
|
|
@item @value{GDBN}INIT_FILENAME
|
|
The default name of @value{GDBN}'s initialization file (normally
|
|
@file{.gdbinit}).
|
|
|
|
@item MEM_FNS_DECLARED
|
|
Your host config file defines this if it includes declarations of
|
|
@code{memcpy} and @code{memset}. Define this to avoid conflicts between
|
|
the native include files and the declarations in @file{defs.h}.
|
|
|
|
@item NO_STD_REGS
|
|
This macro is deprecated.
|
|
|
|
@item NO_SYS_FILE
|
|
Define this if your system does not have a @code{<sys/file.h>}.
|
|
|
|
@item SIGWINCH_HANDLER
|
|
If your host defines @code{SIGWINCH}, you can define this to be the name
|
|
of a function to be called if @code{SIGWINCH} is received.
|
|
|
|
@item SIGWINCH_HANDLER_BODY
|
|
Define this to expand into code that will define the function named by
|
|
the expansion of @code{SIGWINCH_HANDLER}.
|
|
|
|
@item ALIGN_STACK_ON_STARTUP
|
|
@cindex stack alignment
|
|
Define this if your system is of a sort that will crash in
|
|
@code{tgetent} if the stack happens not to be longword-aligned when
|
|
@code{main} is called. This is a rare situation, but is known to occur
|
|
on several different types of systems.
|
|
|
|
@item CRLF_SOURCE_FILES
|
|
@cindex DOS text files
|
|
Define this if host files use @code{\r\n} rather than @code{\n} as a
|
|
line terminator. This will cause source file listings to omit @code{\r}
|
|
characters when printing and it will allow @code{\r\n} line endings of files
|
|
which are ``sourced'' by gdb. It must be possible to open files in binary
|
|
mode using @code{O_BINARY} or, for fopen, @code{"rb"}.
|
|
|
|
@item DEFAULT_PROMPT
|
|
@cindex prompt
|
|
The default value of the prompt string (normally @code{"(gdb) "}).
|
|
|
|
@item DEV_TTY
|
|
@cindex terminal device
|
|
The name of the generic TTY device, defaults to @code{"/dev/tty"}.
|
|
|
|
@item FCLOSE_PROVIDED
|
|
Define this if the system declares @code{fclose} in the headers included
|
|
in @code{defs.h}. This isn't needed unless your compiler is unusually
|
|
anal.
|
|
|
|
@item FOPEN_RB
|
|
Define this if binary files are opened the same way as text files.
|
|
|
|
@item GETENV_PROVIDED
|
|
Define this if the system declares @code{getenv} in its headers included
|
|
in @code{defs.h}. This isn't needed unless your compiler is unusually
|
|
anal.
|
|
|
|
@item HAVE_MMAP
|
|
@findex mmap
|
|
In some cases, use the system call @code{mmap} for reading symbol
|
|
tables. For some machines this allows for sharing and quick updates.
|
|
|
|
@item HAVE_SIGSETMASK
|
|
@findex sigsetmask
|
|
Define this if the host system has job control, but does not define
|
|
@code{sigsetmask}. Currently, this is only true of the RS/6000.
|
|
|
|
@item HAVE_TERMIO
|
|
Define this if the host system has @code{termio.h}.
|
|
|
|
@item HOST_BYTE_ORDER
|
|
@cindex byte order
|
|
The ordering of bytes in the host. This must be defined to be either
|
|
@code{BIG_ENDIAN} or @code{LITTLE_ENDIAN}.
|
|
|
|
@item INT_MAX
|
|
@item INT_MIN
|
|
@item LONG_MAX
|
|
@item UINT_MAX
|
|
@item ULONG_MAX
|
|
Values for host-side constants.
|
|
|
|
@item ISATTY
|
|
Substitute for isatty, if not available.
|
|
|
|
@item LONGEST
|
|
This is the longest integer type available on the host. If not defined,
|
|
it will default to @code{long long} or @code{long}, depending on
|
|
@code{CC_HAS_LONG_LONG}.
|
|
|
|
@item CC_HAS_LONG_LONG
|
|
@cindex @code{long long} data type
|
|
Define this if the host C compiler supports @code{long long}. This is set
|
|
by the @code{configure} script.
|
|
|
|
@item PRINTF_HAS_LONG_LONG
|
|
Define this if the host can handle printing of long long integers via
|
|
the printf format conversion specifier @code{ll}. This is set by the
|
|
@code{configure} script.
|
|
|
|
@item HAVE_LONG_DOUBLE
|
|
Define this if the host C compiler supports @code{long double}. This is
|
|
set by the @code{configure} script.
|
|
|
|
@item PRINTF_HAS_LONG_DOUBLE
|
|
Define this if the host can handle printing of long double float-point
|
|
numbers via the printf format conversion specifier @code{Lg}. This is
|
|
set by the @code{configure} script.
|
|
|
|
@item SCANF_HAS_LONG_DOUBLE
|
|
Define this if the host can handle the parsing of long double
|
|
float-point numbers via the scanf format conversion specifier
|
|
@code{Lg}. This is set by the @code{configure} script.
|
|
|
|
@item LSEEK_NOT_LINEAR
|
|
Define this if @code{lseek (n)} does not necessarily move to byte number
|
|
@code{n} in the file. This is only used when reading source files. It
|
|
is normally faster to define @code{CRLF_SOURCE_FILES} when possible.
|
|
|
|
@item L_SET
|
|
This macro is used as the argument to @code{lseek} (or, most commonly,
|
|
@code{bfd_seek}). FIXME, should be replaced by SEEK_SET instead,
|
|
which is the POSIX equivalent.
|
|
|
|
@item MALLOC_INCOMPATIBLE
|
|
Define this if the system's prototype for @code{malloc} differs from the
|
|
@sc{ansi} definition.
|
|
|
|
@item MMAP_BASE_ADDRESS
|
|
When using HAVE_MMAP, the first mapping should go at this address.
|
|
|
|
@item MMAP_INCREMENT
|
|
when using HAVE_MMAP, this is the increment between mappings.
|
|
|
|
@item NEED_POSIX_SETPGID
|
|
@findex setpgid
|
|
Define this to use the POSIX version of @code{setpgid} to determine
|
|
whether job control is available.
|
|
|
|
@item NORETURN
|
|
If defined, this should be one or more tokens, such as @code{volatile},
|
|
that can be used in both the declaration and definition of functions to
|
|
indicate that they never return. The default is already set correctly
|
|
if compiling with GCC. This will almost never need to be defined.
|
|
|
|
@item ATTR_NORETURN
|
|
If defined, this should be one or more tokens, such as
|
|
@code{__attribute__ ((noreturn))}, that can be used in the declarations
|
|
of functions to indicate that they never return. The default is already
|
|
set correctly if compiling with GCC. This will almost never need to be
|
|
defined.
|
|
|
|
@item USE_GENERIC_DUMMY_FRAMES
|
|
@cindex generic dummy frames
|
|
Define this to 1 if the target is using the generic inferior function
|
|
call code. See @code{blockframe.c} for more information.
|
|
|
|
@item USE_MMALLOC
|
|
@findex mmalloc
|
|
@value{GDBN} will use the @code{mmalloc} library for memory allocation
|
|
for symbol reading if this symbol is defined. Be careful defining it
|
|
since there are systems on which @code{mmalloc} does not work for some
|
|
reason. One example is the DECstation, where its RPC library can't
|
|
cope with our redefinition of @code{malloc} to call @code{mmalloc}.
|
|
When defining @code{USE_MMALLOC}, you will also have to set
|
|
@code{MMALLOC} in the Makefile, to point to the @code{mmalloc} library. This
|
|
define is set when you configure with @samp{--with-mmalloc}.
|
|
|
|
@item NO_MMCHECK
|
|
@findex mmcheck
|
|
Define this if you are using @code{mmalloc}, but don't want the overhead
|
|
of checking the heap with @code{mmcheck}. Note that on some systems,
|
|
the C runtime makes calls to @code{malloc} prior to calling @code{main}, and if
|
|
@code{free} is ever called with these pointers after calling
|
|
@code{mmcheck} to enable checking, a memory corruption abort is certain
|
|
to occur. These systems can still use @code{mmalloc}, but must define
|
|
@code{NO_MMCHECK}.
|
|
|
|
@item MMCHECK_FORCE
|
|
Define this to 1 if the C runtime allocates memory prior to
|
|
@code{mmcheck} being called, but that memory is never freed so we don't
|
|
have to worry about it triggering a memory corruption abort. The
|
|
default is 0, which means that @code{mmcheck} will only install the heap
|
|
checking functions if there has not yet been any memory allocation
|
|
calls, and if it fails to install the functions, @value{GDBN} will issue a
|
|
warning. This is currently defined if you configure using
|
|
@samp{--with-mmalloc}.
|
|
|
|
@item NO_SIGINTERRUPT
|
|
@findex siginterrupt
|
|
Define this to indicate that @code{siginterrupt} is not available.
|
|
|
|
@item R_OK
|
|
Define if this is not in a system header file (typically, @file{unistd.h}).
|
|
|
|
@item SEEK_CUR
|
|
@item SEEK_SET
|
|
Define these to appropriate value for the system @code{lseek}, if not already
|
|
defined.
|
|
|
|
@item STOP_SIGNAL
|
|
This is the signal for stopping @value{GDBN}. Defaults to
|
|
@code{SIGTSTP}. (Only redefined for the Convex.)
|
|
|
|
@item USE_O_NOCTTY
|
|
Define this if the interior's tty should be opened with the @code{O_NOCTTY}
|
|
flag. (FIXME: This should be a native-only flag, but @file{inflow.c} is
|
|
always linked in.)
|
|
|
|
@item USG
|
|
Means that System V (prior to SVR4) include files are in use. (FIXME:
|
|
This symbol is abused in @file{infrun.c}, @file{regex.c},
|
|
@file{remote-nindy.c}, and @file{utils.c} for other things, at the
|
|
moment.)
|
|
|
|
@item lint
|
|
Define this to help placate @code{lint} in some situations.
|
|
|
|
@item volatile
|
|
Define this to override the defaults of @code{__volatile__} or
|
|
@code{/**/}.
|
|
@end ftable
|
|
|
|
|
|
@node Target Architecture Definition
|
|
|
|
@chapter Target Architecture Definition
|
|
|
|
@cindex target architecture definition
|
|
@value{GDBN}'s target architecture defines what sort of
|
|
machine-language programs @value{GDBN} can work with, and how it works
|
|
with them.
|
|
|
|
At present, the target architecture definition consists of a number of C
|
|
macros.
|
|
|
|
@section Registers and Memory
|
|
|
|
@value{GDBN}'s model of the target machine is rather simple.
|
|
@value{GDBN} assumes the machine includes a bank of registers and a
|
|
block of memory. Each register may have a different size.
|
|
|
|
@value{GDBN} does not have a magical way to match up with the
|
|
compiler's idea of which registers are which; however, it is critical
|
|
that they do match up accurately. The only way to make this work is
|
|
to get accurate information about the order that the compiler uses,
|
|
and to reflect that in the @code{REGISTER_NAME} and related macros.
|
|
|
|
@value{GDBN} can handle big-endian, little-endian, and bi-endian architectures.
|
|
|
|
@section Pointers Are Not Always Addresses
|
|
@cindex pointer representation
|
|
@cindex address representation
|
|
@cindex word-addressed machines
|
|
@cindex separate data and code address spaces
|
|
@cindex spaces, separate data and code address
|
|
@cindex address spaces, separate data and code
|
|
@cindex code pointers, word-addressed
|
|
@cindex converting between pointers and addresses
|
|
@cindex D10V addresses
|
|
|
|
On almost all 32-bit architectures, the representation of a pointer is
|
|
indistinguishable from the representation of some fixed-length number
|
|
whose value is the byte address of the object pointed to. On such
|
|
machines, the words ``pointer'' and ``address'' can be used interchangeably.
|
|
However, architectures with smaller word sizes are often cramped for
|
|
address space, so they may choose a pointer representation that breaks this
|
|
identity, and allows a larger code address space.
|
|
|
|
For example, the Mitsubishi D10V is a 16-bit VLIW processor whose
|
|
instructions are 32 bits long@footnote{Some D10V instructions are
|
|
actually pairs of 16-bit sub-instructions. However, since you can't
|
|
jump into the middle of such a pair, code addresses can only refer to
|
|
full 32 bit instructions, which is what matters in this explanation.}.
|
|
If the D10V used ordinary byte addresses to refer to code locations,
|
|
then the processor would only be able to address 64kb of instructions.
|
|
However, since instructions must be aligned on four-byte boundaries, the
|
|
low two bits of any valid instruction's byte address are always
|
|
zero---byte addresses waste two bits. So instead of byte addresses,
|
|
the D10V uses word addresses---byte addresses shifted right two bits---to
|
|
refer to code. Thus, the D10V can use 16-bit words to address 256kb of
|
|
code space.
|
|
|
|
However, this means that code pointers and data pointers have different
|
|
forms on the D10V. The 16-bit word @code{0xC020} refers to byte address
|
|
@code{0xC020} when used as a data address, but refers to byte address
|
|
@code{0x30080} when used as a code address.
|
|
|
|
(The D10V also uses separate code and data address spaces, which also
|
|
affects the correspondence between pointers and addresses, but we're
|
|
going to ignore that here; this example is already too long.)
|
|
|
|
To cope with architectures like this---the D10V is not the only
|
|
one!---@value{GDBN} tries to distinguish between @dfn{addresses}, which are
|
|
byte numbers, and @dfn{pointers}, which are the target's representation
|
|
of an address of a particular type of data. In the example above,
|
|
@code{0xC020} is the pointer, which refers to one of the addresses
|
|
@code{0xC020} or @code{0x30080}, depending on the type imposed upon it.
|
|
@value{GDBN} provides functions for turning a pointer into an address
|
|
and vice versa, in the appropriate way for the current architecture.
|
|
|
|
Unfortunately, since addresses and pointers are identical on almost all
|
|
processors, this distinction tends to bit-rot pretty quickly. Thus,
|
|
each time you port @value{GDBN} to an architecture which does
|
|
distinguish between pointers and addresses, you'll probably need to
|
|
clean up some architecture-independent code.
|
|
|
|
Here are functions which convert between pointers and addresses:
|
|
|
|
@deftypefun CORE_ADDR extract_typed_address (void *@var{buf}, struct type *@var{type})
|
|
Treat the bytes at @var{buf} as a pointer or reference of type
|
|
@var{type}, and return the address it represents, in a manner
|
|
appropriate for the current architecture. This yields an address
|
|
@value{GDBN} can use to read target memory, disassemble, etc. Note that
|
|
@var{buf} refers to a buffer in @value{GDBN}'s memory, not the
|
|
inferior's.
|
|
|
|
For example, if the current architecture is the Intel x86, this function
|
|
extracts a little-endian integer of the appropriate length from
|
|
@var{buf} and returns it. However, if the current architecture is the
|
|
D10V, this function will return a 16-bit integer extracted from
|
|
@var{buf}, multiplied by four if @var{type} is a pointer to a function.
|
|
|
|
If @var{type} is not a pointer or reference type, then this function
|
|
will signal an internal error.
|
|
@end deftypefun
|
|
|
|
@deftypefun CORE_ADDR store_typed_address (void *@var{buf}, struct type *@var{type}, CORE_ADDR @var{addr})
|
|
Store the address @var{addr} in @var{buf}, in the proper format for a
|
|
pointer of type @var{type} in the current architecture. Note that
|
|
@var{buf} refers to a buffer in @value{GDBN}'s memory, not the
|
|
inferior's.
|
|
|
|
For example, if the current architecture is the Intel x86, this function
|
|
stores @var{addr} unmodified as a little-endian integer of the
|
|
appropriate length in @var{buf}. However, if the current architecture
|
|
is the D10V, this function divides @var{addr} by four if @var{type} is
|
|
a pointer to a function, and then stores it in @var{buf}.
|
|
|
|
If @var{type} is not a pointer or reference type, then this function
|
|
will signal an internal error.
|
|
@end deftypefun
|
|
|
|
@deftypefun CORE_ADDR value_as_pointer (value_ptr @var{val})
|
|
Assuming that @var{val} is a pointer, return the address it represents,
|
|
as appropriate for the current architecture.
|
|
|
|
This function actually works on integral values, as well as pointers.
|
|
For pointers, it performs architecture-specific conversions as
|
|
described above for @code{extract_typed_address}.
|
|
@end deftypefun
|
|
|
|
@deftypefun CORE_ADDR value_from_pointer (struct type *@var{type}, CORE_ADDR @var{addr})
|
|
Create and return a value representing a pointer of type @var{type} to
|
|
the address @var{addr}, as appropriate for the current architecture.
|
|
This function performs architecture-specific conversions as described
|
|
above for @code{store_typed_address}.
|
|
@end deftypefun
|
|
|
|
|
|
@value{GDBN} also provides functions that do the same tasks, but assume
|
|
that pointers are simply byte addresses; they aren't sensitive to the
|
|
current architecture, beyond knowing the appropriate endianness.
|
|
|
|
@deftypefun CORE_ADDR extract_address (void *@var{addr}, int len)
|
|
Extract a @var{len}-byte number from @var{addr} in the appropriate
|
|
endianness for the current architecture, and return it. Note that
|
|
@var{addr} refers to @value{GDBN}'s memory, not the inferior's.
|
|
|
|
This function should only be used in architecture-specific code; it
|
|
doesn't have enough information to turn bits into a true address in the
|
|
appropriate way for the current architecture. If you can, use
|
|
@code{extract_typed_address} instead.
|
|
@end deftypefun
|
|
|
|
@deftypefun void store_address (void *@var{addr}, int @var{len}, LONGEST @var{val})
|
|
Store @var{val} at @var{addr} as a @var{len}-byte integer, in the
|
|
appropriate endianness for the current architecture. Note that
|
|
@var{addr} refers to a buffer in @value{GDBN}'s memory, not the
|
|
inferior's.
|
|
|
|
This function should only be used in architecture-specific code; it
|
|
doesn't have enough information to turn a true address into bits in the
|
|
appropriate way for the current architecture. If you can, use
|
|
@code{store_typed_address} instead.
|
|
@end deftypefun
|
|
|
|
|
|
Here are some macros which architectures can define to indicate the
|
|
relationship between pointers and addresses. These have default
|
|
definitions, appropriate for architectures on which all pointers are
|
|
simple byte addresses.
|
|
|
|
@deftypefn {Target Macro} CORE_ADDR POINTER_TO_ADDRESS (struct type *@var{type}, char *@var{buf})
|
|
Assume that @var{buf} holds a pointer of type @var{type}, in the
|
|
appropriate format for the current architecture. Return the byte
|
|
address the pointer refers to.
|
|
|
|
This function may safely assume that @var{type} is either a pointer or a
|
|
C@t{++} reference type.
|
|
@end deftypefn
|
|
|
|
@deftypefn {Target Macro} void ADDRESS_TO_POINTER (struct type *@var{type}, char *@var{buf}, CORE_ADDR @var{addr})
|
|
Store in @var{buf} a pointer of type @var{type} representing the address
|
|
@var{addr}, in the appropriate format for the current architecture.
|
|
|
|
This function may safely assume that @var{type} is either a pointer or a
|
|
C@t{++} reference type.
|
|
@end deftypefn
|
|
|
|
|
|
@section Using Different Register and Memory Data Representations
|
|
@cindex raw representation
|
|
@cindex virtual representation
|
|
@cindex representations, raw and virtual
|
|
@cindex register data formats, converting
|
|
@cindex @code{struct value}, converting register contents to
|
|
|
|
Some architectures use one representation for a value when it lives in a
|
|
register, but use a different representation when it lives in memory.
|
|
In @value{GDBN}'s terminology, the @dfn{raw} representation is the one used in
|
|
the target registers, and the @dfn{virtual} representation is the one
|
|
used in memory, and within @value{GDBN} @code{struct value} objects.
|
|
|
|
For almost all data types on almost all architectures, the virtual and
|
|
raw representations are identical, and no special handling is needed.
|
|
However, they do occasionally differ. For example:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The x86 architecture supports an 80-bit @code{long double} type. However, when
|
|
we store those values in memory, they occupy twelve bytes: the
|
|
floating-point number occupies the first ten, and the final two bytes
|
|
are unused. This keeps the values aligned on four-byte boundaries,
|
|
allowing more efficient access. Thus, the x86 80-bit floating-point
|
|
type is the raw representation, and the twelve-byte loosely-packed
|
|
arrangement is the virtual representation.
|
|
|
|
@item
|
|
Some 64-bit MIPS targets present 32-bit registers to @value{GDBN} as 64-bit
|
|
registers, with garbage in their upper bits. @value{GDBN} ignores the top 32
|
|
bits. Thus, the 64-bit form, with garbage in the upper 32 bits, is the
|
|
raw representation, and the trimmed 32-bit representation is the
|
|
virtual representation.
|
|
@end itemize
|
|
|
|
In general, the raw representation is determined by the architecture, or
|
|
@value{GDBN}'s interface to the architecture, while the virtual representation
|
|
can be chosen for @value{GDBN}'s convenience. @value{GDBN}'s register file,
|
|
@code{registers}, holds the register contents in raw format, and the
|
|
@value{GDBN} remote protocol transmits register values in raw format.
|
|
|
|
Your architecture may define the following macros to request
|
|
conversions between the raw and virtual format:
|
|
|
|
@deftypefn {Target Macro} int REGISTER_CONVERTIBLE (int @var{reg})
|
|
Return non-zero if register number @var{reg}'s value needs different raw
|
|
and virtual formats.
|
|
|
|
You should not use @code{REGISTER_CONVERT_TO_VIRTUAL} for a register
|
|
unless this macro returns a non-zero value for that register.
|
|
@end deftypefn
|
|
|
|
@deftypefn {Target Macro} int REGISTER_RAW_SIZE (int @var{reg})
|
|
The size of register number @var{reg}'s raw value. This is the number
|
|
of bytes the register will occupy in @code{registers}, or in a @value{GDBN}
|
|
remote protocol packet.
|
|
@end deftypefn
|
|
|
|
@deftypefn {Target Macro} int REGISTER_VIRTUAL_SIZE (int @var{reg})
|
|
The size of register number @var{reg}'s value, in its virtual format.
|
|
This is the size a @code{struct value}'s buffer will have, holding that
|
|
register's value.
|
|
@end deftypefn
|
|
|
|
@deftypefn {Target Macro} struct type *REGISTER_VIRTUAL_TYPE (int @var{reg})
|
|
This is the type of the virtual representation of register number
|
|
@var{reg}. Note that there is no need for a macro giving a type for the
|
|
register's raw form; once the register's value has been obtained, @value{GDBN}
|
|
always uses the virtual form.
|
|
@end deftypefn
|
|
|
|
@deftypefn {Target Macro} void REGISTER_CONVERT_TO_VIRTUAL (int @var{reg}, struct type *@var{type}, char *@var{from}, char *@var{to})
|
|
Convert the value of register number @var{reg} to @var{type}, which
|
|
should always be @code{REGISTER_VIRTUAL_TYPE (@var{reg})}. The buffer
|
|
at @var{from} holds the register's value in raw format; the macro should
|
|
convert the value to virtual format, and place it at @var{to}.
|
|
|
|
Note that @code{REGISTER_CONVERT_TO_VIRTUAL} and
|
|
@code{REGISTER_CONVERT_TO_RAW} take their @var{reg} and @var{type}
|
|
arguments in different orders.
|
|
|
|
You should only use @code{REGISTER_CONVERT_TO_VIRTUAL} with registers
|
|
for which the @code{REGISTER_CONVERTIBLE} macro returns a non-zero
|
|
value.
|
|
@end deftypefn
|
|
|
|
@deftypefn {Target Macro} void REGISTER_CONVERT_TO_RAW (struct type *@var{type}, int @var{reg}, char *@var{from}, char *@var{to})
|
|
Convert the value of register number @var{reg} to @var{type}, which
|
|
should always be @code{REGISTER_VIRTUAL_TYPE (@var{reg})}. The buffer
|
|
at @var{from} holds the register's value in raw format; the macro should
|
|
convert the value to virtual format, and place it at @var{to}.
|
|
|
|
Note that REGISTER_CONVERT_TO_VIRTUAL and REGISTER_CONVERT_TO_RAW take
|
|
their @var{reg} and @var{type} arguments in different orders.
|
|
@end deftypefn
|
|
|
|
|
|
@section Frame Interpretation
|
|
|
|
@section Inferior Call Setup
|
|
|
|
@section Compiler Characteristics
|
|
|
|
@section Target Conditionals
|
|
|
|
This section describes the macros that you can use to define the target
|
|
machine.
|
|
|
|
@table @code
|
|
|
|
@item ADDITIONAL_OPTIONS
|
|
@itemx ADDITIONAL_OPTION_CASES
|
|
@itemx ADDITIONAL_OPTION_HANDLER
|
|
@itemx ADDITIONAL_OPTION_HELP
|
|
@findex ADDITIONAL_OPTION_HELP
|
|
@findex ADDITIONAL_OPTION_HANDLER
|
|
@findex ADDITIONAL_OPTION_CASES
|
|
@findex ADDITIONAL_OPTIONS
|
|
These are a set of macros that allow the addition of additional command
|
|
line options to @value{GDBN}. They are currently used only for the unsupported
|
|
i960 Nindy target, and should not be used in any other configuration.
|
|
|
|
@item ADDR_BITS_REMOVE (addr)
|
|
@findex ADDR_BITS_REMOVE
|
|
If a raw machine instruction address includes any bits that are not
|
|
really part of the address, then define this macro to expand into an
|
|
expression that zeroes those bits in @var{addr}. This is only used for
|
|
addresses of instructions, and even then not in all contexts.
|
|
|
|
For example, the two low-order bits of the PC on the Hewlett-Packard PA
|
|
2.0 architecture contain the privilege level of the corresponding
|
|
instruction. Since instructions must always be aligned on four-byte
|
|
boundaries, the processor masks out these bits to generate the actual
|
|
address of the instruction. ADDR_BITS_REMOVE should filter out these
|
|
bits with an expression such as @code{((addr) & ~3)}.
|
|
|
|
@item ADDRESS_TO_POINTER (@var{type}, @var{buf}, @var{addr})
|
|
@findex ADDRESS_TO_POINTER
|
|
Store in @var{buf} a pointer of type @var{type} representing the address
|
|
@var{addr}, in the appropriate format for the current architecture.
|
|
This macro may safely assume that @var{type} is either a pointer or a
|
|
C@t{++} reference type.
|
|
@xref{Target Architecture Definition, , Pointers Are Not Always Addresses}.
|
|
|
|
@item BEFORE_MAIN_LOOP_HOOK
|
|
@findex BEFORE_MAIN_LOOP_HOOK
|
|
Define this to expand into any code that you want to execute before the
|
|
main loop starts. Although this is not, strictly speaking, a target
|
|
conditional, that is how it is currently being used. Note that if a
|
|
configuration were to define it one way for a host and a different way
|
|
for the target, @value{GDBN} will probably not compile, let alone run
|
|
correctly. This macro is currently used only for the unsupported i960 Nindy
|
|
target, and should not be used in any other configuration.
|
|
|
|
@item BELIEVE_PCC_PROMOTION
|
|
@findex BELIEVE_PCC_PROMOTION
|
|
Define if the compiler promotes a @code{short} or @code{char}
|
|
parameter to an @code{int}, but still reports the parameter as its
|
|
original type, rather than the promoted type.
|
|
|
|
@item BELIEVE_PCC_PROMOTION_TYPE
|
|
@findex BELIEVE_PCC_PROMOTION_TYPE
|
|
Define this if @value{GDBN} should believe the type of a @code{short}
|
|
argument when compiled by @code{pcc}, but look within a full int space to get
|
|
its value. Only defined for Sun-3 at present.
|
|
|
|
@item BITS_BIG_ENDIAN
|
|
@findex BITS_BIG_ENDIAN
|
|
Define this if the numbering of bits in the targets does @strong{not} match the
|
|
endianness of the target byte order. A value of 1 means that the bits
|
|
are numbered in a big-endian bit order, 0 means little-endian.
|
|
|
|
@item BREAKPOINT
|
|
@findex BREAKPOINT
|
|
This is the character array initializer for the bit pattern to put into
|
|
memory where a breakpoint is set. Although it's common to use a trap
|
|
instruction for a breakpoint, it's not required; for instance, the bit
|
|
pattern could be an invalid instruction. The breakpoint must be no
|
|
longer than the shortest instruction of the architecture.
|
|
|
|
@code{BREAKPOINT} has been deprecated in favor of
|
|
@code{BREAKPOINT_FROM_PC}.
|
|
|
|
@item BIG_BREAKPOINT
|
|
@itemx LITTLE_BREAKPOINT
|
|
@findex LITTLE_BREAKPOINT
|
|
@findex BIG_BREAKPOINT
|
|
Similar to BREAKPOINT, but used for bi-endian targets.
|
|
|
|
@code{BIG_BREAKPOINT} and @code{LITTLE_BREAKPOINT} have been deprecated in
|
|
favor of @code{BREAKPOINT_FROM_PC}.
|
|
|
|
@item REMOTE_BREAKPOINT
|
|
@itemx LITTLE_REMOTE_BREAKPOINT
|
|
@itemx BIG_REMOTE_BREAKPOINT
|
|
@findex BIG_REMOTE_BREAKPOINT
|
|
@findex LITTLE_REMOTE_BREAKPOINT
|
|
@findex REMOTE_BREAKPOINT
|
|
Similar to BREAKPOINT, but used for remote targets.
|
|
|
|
@code{BIG_REMOTE_BREAKPOINT} and @code{LITTLE_REMOTE_BREAKPOINT} have been
|
|
deprecated in favor of @code{BREAKPOINT_FROM_PC}.
|
|
|
|
@item BREAKPOINT_FROM_PC (@var{pcptr}, @var{lenptr})
|
|
@findex BREAKPOINT_FROM_PC
|
|
Use the program counter to determine the contents and size of a
|
|
breakpoint instruction. It returns a pointer to a string of bytes
|
|
that encode a breakpoint instruction, stores the length of the string
|
|
to *@var{lenptr}, and adjusts pc (if necessary) to point to the actual
|
|
memory location where the breakpoint should be inserted.
|
|
|
|
Although it is common to use a trap instruction for a breakpoint, it's
|
|
not required; for instance, the bit pattern could be an invalid
|
|
instruction. The breakpoint must be no longer than the shortest
|
|
instruction of the architecture.
|
|
|
|
Replaces all the other @var{BREAKPOINT} macros.
|
|
|
|
@item MEMORY_INSERT_BREAKPOINT (@var{addr}, @var{contents_cache})
|
|
@itemx MEMORY_REMOVE_BREAKPOINT (@var{addr}, @var{contents_cache})
|
|
@findex MEMORY_REMOVE_BREAKPOINT
|
|
@findex MEMORY_INSERT_BREAKPOINT
|
|
Insert or remove memory based breakpoints. Reasonable defaults
|
|
(@code{default_memory_insert_breakpoint} and
|
|
@code{default_memory_remove_breakpoint} respectively) have been
|
|
provided so that it is not necessary to define these for most
|
|
architectures. Architectures which may want to define
|
|
@code{MEMORY_INSERT_BREAKPOINT} and @code{MEMORY_REMOVE_BREAKPOINT} will
|
|
likely have instructions that are oddly sized or are not stored in a
|
|
conventional manner.
|
|
|
|
It may also be desirable (from an efficiency standpoint) to define
|
|
custom breakpoint insertion and removal routines if
|
|
@code{BREAKPOINT_FROM_PC} needs to read the target's memory for some
|
|
reason.
|
|
|
|
@item CALL_DUMMY_P
|
|
@findex CALL_DUMMY_P
|
|
A C expresson that is non-zero when the target suports inferior function
|
|
calls.
|
|
|
|
@item CALL_DUMMY_WORDS
|
|
@findex CALL_DUMMY_WORDS
|
|
Pointer to an array of @code{LONGEST} words of data containing
|
|
host-byte-ordered @code{REGISTER_BYTES} sized values that partially
|
|
specify the sequence of instructions needed for an inferior function
|
|
call.
|
|
|
|
Should be deprecated in favor of a macro that uses target-byte-ordered
|
|
data.
|
|
|
|
@item SIZEOF_CALL_DUMMY_WORDS
|
|
@findex SIZEOF_CALL_DUMMY_WORDS
|
|
The size of @code{CALL_DUMMY_WORDS}. When @code{CALL_DUMMY_P} this must
|
|
return a positive value. See also @code{CALL_DUMMY_LENGTH}.
|
|
|
|
@item CALL_DUMMY
|
|
@findex CALL_DUMMY
|
|
A static initializer for @code{CALL_DUMMY_WORDS}. Deprecated.
|
|
|
|
@item CALL_DUMMY_LOCATION
|
|
@findex CALL_DUMMY_LOCATION
|
|
See the file @file{inferior.h}.
|
|
|
|
@item CALL_DUMMY_STACK_ADJUST
|
|
@findex CALL_DUMMY_STACK_ADJUST
|
|
Stack adjustment needed when performing an inferior function call.
|
|
|
|
Should be deprecated in favor of something like @code{STACK_ALIGN}.
|
|
|
|
@item CALL_DUMMY_STACK_ADJUST_P
|
|
@findex CALL_DUMMY_STACK_ADJUST_P
|
|
Predicate for use of @code{CALL_DUMMY_STACK_ADJUST}.
|
|
|
|
Should be deprecated in favor of something like @code{STACK_ALIGN}.
|
|
|
|
@item CANNOT_FETCH_REGISTER (@var{regno})
|
|
@findex CANNOT_FETCH_REGISTER
|
|
A C expression that should be nonzero if @var{regno} cannot be fetched
|
|
from an inferior process. This is only relevant if
|
|
@code{FETCH_INFERIOR_REGISTERS} is not defined.
|
|
|
|
@item CANNOT_STORE_REGISTER (@var{regno})
|
|
@findex CANNOT_STORE_REGISTER
|
|
A C expression that should be nonzero if @var{regno} should not be
|
|
written to the target. This is often the case for program counters,
|
|
status words, and other special registers. If this is not defined,
|
|
@value{GDBN} will assume that all registers may be written.
|
|
|
|
@item DO_DEFERRED_STORES
|
|
@itemx CLEAR_DEFERRED_STORES@item
|
|
@findex CLEAR_DEFERRED_STORES
|
|
@findex DO_DEFERRED_STORES
|
|
Define this to execute any deferred stores of registers into the inferior,
|
|
and to cancel any deferred stores.
|
|
|
|
Currently only implemented correctly for native Sparc configurations?
|
|
|
|
@item COERCE_FLOAT_TO_DOUBLE (@var{formal}, @var{actual})
|
|
@findex COERCE_FLOAT_TO_DOUBLE
|
|
@cindex promotion to @code{double}
|
|
If we are calling a function by hand, and the function was declared
|
|
(according to the debug info) without a prototype, should we
|
|
automatically promote @code{float}s to @code{double}s? This macro
|
|
must evaluate to non-zero if we should, or zero if we should leave the
|
|
value alone.
|
|
|
|
The argument @var{actual} is the type of the value we want to pass to
|
|
the function. The argument @var{formal} is the type of this argument,
|
|
as it appears in the function's definition. Note that @var{formal} may
|
|
be zero if we have no debugging information for the function, or if
|
|
we're passing more arguments than are officially declared (for example,
|
|
varargs). This macro is never invoked if the function definitely has a
|
|
prototype.
|
|
|
|
@findex set_gdbarch_coerce_float_to_double
|
|
@findex standard_coerce_float_to_double
|
|
The default behavior is to promote only when we have no type information
|
|
for the formal parameter. This is different from the obvious behavior,
|
|
which would be to promote whenever we have no prototype, just as the
|
|
compiler does. It's annoying, but some older targets rely on this. If
|
|
you want @value{GDBN} to follow the typical compiler behavior---to always
|
|
promote when there is no prototype in scope---your gdbarch @code{init}
|
|
function can call @code{set_gdbarch_coerce_float_to_double} and select
|
|
the @code{standard_coerce_float_to_double} function.
|
|
|
|
@item CPLUS_MARKER
|
|
@findex CPLUS_MARKERz
|
|
Define this to expand into the character that G@t{++} uses to distinguish
|
|
compiler-generated identifiers from programmer-specified identifiers.
|
|
By default, this expands into @code{'$'}. Most System V targets should
|
|
define this to @code{'.'}.
|
|
|
|
@item DBX_PARM_SYMBOL_CLASS
|
|
@findex DBX_PARM_SYMBOL_CLASS
|
|
Hook for the @code{SYMBOL_CLASS} of a parameter when decoding DBX symbol
|
|
information. In the i960, parameters can be stored as locals or as
|
|
args, depending on the type of the debug record.
|
|
|
|
@item DECR_PC_AFTER_BREAK
|
|
@findex DECR_PC_AFTER_BREAK
|
|
Define this to be the amount by which to decrement the PC after the
|
|
program encounters a breakpoint. This is often the number of bytes in
|
|
@code{BREAKPOINT}, though not always. For most targets this value will be 0.
|
|
|
|
@item DECR_PC_AFTER_HW_BREAK
|
|
@findex DECR_PC_AFTER_HW_BREAK
|
|
Similarly, for hardware breakpoints.
|
|
|
|
@item DISABLE_UNSETTABLE_BREAK (@var{addr})
|
|
@findex DISABLE_UNSETTABLE_BREAK
|
|
If defined, this should evaluate to 1 if @var{addr} is in a shared
|
|
library in which breakpoints cannot be set and so should be disabled.
|
|
|
|
@item DO_REGISTERS_INFO
|
|
@findex DO_REGISTERS_INFO
|
|
If defined, use this to print the value of a register or all registers.
|
|
|
|
@item DWARF_REG_TO_REGNUM
|
|
@findex DWARF_REG_TO_REGNUM
|
|
Convert DWARF register number into @value{GDBN} regnum. If not defined,
|
|
no conversion will be performed.
|
|
|
|
@item DWARF2_REG_TO_REGNUM
|
|
@findex DWARF2_REG_TO_REGNUM
|
|
Convert DWARF2 register number into @value{GDBN} regnum. If not
|
|
defined, no conversion will be performed.
|
|
|
|
@item ECOFF_REG_TO_REGNUM
|
|
@findex ECOFF_REG_TO_REGNUM
|
|
Convert ECOFF register number into @value{GDBN} regnum. If not defined,
|
|
no conversion will be performed.
|
|
|
|
@item END_OF_TEXT_DEFAULT
|
|
@findex END_OF_TEXT_DEFAULT
|
|
This is an expression that should designate the end of the text section.
|
|
@c (? FIXME ?)
|
|
|
|
@item EXTRACT_RETURN_VALUE(@var{type}, @var{regbuf}, @var{valbuf})
|
|
@findex EXTRACT_RETURN_VALUE
|
|
Define this to extract a function's return value of type @var{type} from
|
|
the raw register state @var{regbuf} and copy that, in virtual format,
|
|
into @var{valbuf}.
|
|
|
|
@item EXTRACT_STRUCT_VALUE_ADDRESS(@var{regbuf})
|
|
@findex EXTRACT_STRUCT_VALUE_ADDRESS
|
|
When @code{EXTRACT_STRUCT_VALUE_ADDRESS_P} is non-zero, this is used to extract
|
|
from an array @var{regbuf} (containing the raw register state) the
|
|
address in which a function should return its structure value, as a
|
|
@code{CORE_ADDR} (or an expression that can be used as one).
|
|
|
|
@item EXTRACT_STRUCT_VALUE_ADDRESS_P
|
|
@findex EXTRACT_STRUCT_VALUE_ADDRESS_P
|
|
Predicate for @code{EXTRACT_STRUCT_VALUE_ADDRESS}.
|
|
|
|
@item FLOAT_INFO
|
|
@findex FLOAT_INFO
|
|
If defined, then the @samp{info float} command will print information about
|
|
the processor's floating point unit.
|
|
|
|
@item FP_REGNUM
|
|
@findex FP_REGNUM
|
|
If the virtual frame pointer is kept in a register, then define this
|
|
macro to be the number (greater than or equal to zero) of that register.
|
|
|
|
This should only need to be defined if @code{TARGET_READ_FP} and
|
|
@code{TARGET_WRITE_FP} are not defined.
|
|
|
|
@item FRAMELESS_FUNCTION_INVOCATION(@var{fi})
|
|
@findex FRAMELESS_FUNCTION_INVOCATION
|
|
Define this to an expression that returns 1 if the function invocation
|
|
represented by @var{fi} does not have a stack frame associated with it.
|
|
Otherwise return 0.
|
|
|
|
@item FRAME_ARGS_ADDRESS_CORRECT@item
|
|
@findex FRAME_ARGS_ADDRESS_CORRECT
|
|
See @file{stack.c}.
|
|
|
|
@item FRAME_CHAIN(@var{frame})
|
|
@findex FRAME_CHAIN
|
|
Given @var{frame}, return a pointer to the calling frame.
|
|
|
|
@item FRAME_CHAIN_COMBINE(@var{chain}, @var{frame})
|
|
@findex FRAME_CHAIN_COMBINE
|
|
Define this to take the frame chain pointer and the frame's nominal
|
|
address and produce the nominal address of the caller's frame.
|
|
Presently only defined for HP PA.
|
|
|
|
@item FRAME_CHAIN_VALID(@var{chain}, @var{thisframe})
|
|
@findex FRAME_CHAIN_VALID
|
|
Define this to be an expression that returns zero if the given frame is
|
|
an outermost frame, with no caller, and nonzero otherwise. Several
|
|
common definitions are available:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@code{file_frame_chain_valid} is nonzero if the chain pointer is nonzero
|
|
and given frame's PC is not inside the startup file (such as
|
|
@file{crt0.o}).
|
|
|
|
@item
|
|
@code{func_frame_chain_valid} is nonzero if the chain
|
|
pointer is nonzero and the given frame's PC is not in @code{main} or a
|
|
known entry point function (such as @code{_start}).
|
|
|
|
@item
|
|
@code{generic_file_frame_chain_valid} and
|
|
@code{generic_func_frame_chain_valid} are equivalent implementations for
|
|
targets using generic dummy frames.
|
|
@end itemize
|
|
|
|
@item FRAME_INIT_SAVED_REGS(@var{frame})
|
|
@findex FRAME_INIT_SAVED_REGS
|
|
See @file{frame.h}. Determines the address of all registers in the
|
|
current stack frame storing each in @code{frame->saved_regs}. Space for
|
|
@code{frame->saved_regs} shall be allocated by
|
|
@code{FRAME_INIT_SAVED_REGS} using either
|
|
@code{frame_saved_regs_zalloc} or @code{frame_obstack_alloc}.
|
|
|
|
@code{FRAME_FIND_SAVED_REGS} and @code{EXTRA_FRAME_INFO} are deprecated.
|
|
|
|
@item FRAME_NUM_ARGS (@var{fi})
|
|
@findex FRAME_NUM_ARGS
|
|
For the frame described by @var{fi} return the number of arguments that
|
|
are being passed. If the number of arguments is not known, return
|
|
@code{-1}.
|
|
|
|
@item FRAME_SAVED_PC(@var{frame})
|
|
@findex FRAME_SAVED_PC
|
|
Given @var{frame}, return the pc saved there. This is the return
|
|
address.
|
|
|
|
@item FUNCTION_EPILOGUE_SIZE
|
|
@findex FUNCTION_EPILOGUE_SIZE
|
|
For some COFF targets, the @code{x_sym.x_misc.x_fsize} field of the
|
|
function end symbol is 0. For such targets, you must define
|
|
@code{FUNCTION_EPILOGUE_SIZE} to expand into the standard size of a
|
|
function's epilogue.
|
|
|
|
@item FUNCTION_START_OFFSET
|
|
@findex FUNCTION_START_OFFSET
|
|
An integer, giving the offset in bytes from a function's address (as
|
|
used in the values of symbols, function pointers, etc.), and the
|
|
function's first genuine instruction.
|
|
|
|
This is zero on almost all machines: the function's address is usually
|
|
the address of its first instruction. However, on the VAX, for example,
|
|
each function starts with two bytes containing a bitmask indicating
|
|
which registers to save upon entry to the function. The VAX @code{call}
|
|
instructions check this value, and save the appropriate registers
|
|
automatically. Thus, since the offset from the function's address to
|
|
its first instruction is two bytes, @code{FUNCTION_START_OFFSET} would
|
|
be 2 on the VAX.
|
|
|
|
@item GCC_COMPILED_FLAG_SYMBOL
|
|
@itemx GCC2_COMPILED_FLAG_SYMBOL
|
|
@findex GCC2_COMPILED_FLAG_SYMBOL
|
|
@findex GCC_COMPILED_FLAG_SYMBOL
|
|
If defined, these are the names of the symbols that @value{GDBN} will
|
|
look for to detect that GCC compiled the file. The default symbols
|
|
are @code{gcc_compiled.} and @code{gcc2_compiled.},
|
|
respectively. (Currently only defined for the Delta 68.)
|
|
|
|
@item @value{GDBN}_MULTI_ARCH
|
|
@findex @value{GDBN}_MULTI_ARCH
|
|
If defined and non-zero, enables suport for multiple architectures
|
|
within @value{GDBN}.
|
|
|
|
This support can be enabled at two levels. At level one, only
|
|
definitions for previously undefined macros are provided; at level two,
|
|
a multi-arch definition of all architecture dependant macros will be
|
|
defined.
|
|
|
|
@item @value{GDBN}_TARGET_IS_HPPA
|
|
@findex @value{GDBN}_TARGET_IS_HPPA
|
|
This determines whether horrible kludge code in @file{dbxread.c} and
|
|
@file{partial-stab.h} is used to mangle multiple-symbol-table files from
|
|
HPPA's. This should all be ripped out, and a scheme like @file{elfread.c}
|
|
used instead.
|
|
|
|
@item GET_LONGJMP_TARGET
|
|
@findex GET_LONGJMP_TARGET
|
|
For most machines, this is a target-dependent parameter. On the
|
|
DECstation and the Iris, this is a native-dependent parameter, since
|
|
trhe header file @file{setjmp.h} is needed to define it.
|
|
|
|
This macro determines the target PC address that @code{longjmp} will jump to,
|
|
assuming that we have just stopped at a @code{longjmp} breakpoint. It takes a
|
|
@code{CORE_ADDR *} as argument, and stores the target PC value through this
|
|
pointer. It examines the current state of the machine as needed.
|
|
|
|
@item GET_SAVED_REGISTER
|
|
@findex GET_SAVED_REGISTER
|
|
@findex get_saved_register
|
|
Define this if you need to supply your own definition for the function
|
|
@code{get_saved_register}.
|
|
|
|
@item HAVE_REGISTER_WINDOWS
|
|
@findex HAVE_REGISTER_WINDOWS
|
|
Define this if the target has register windows.
|
|
|
|
@item REGISTER_IN_WINDOW_P (@var{regnum})
|
|
@findex REGISTER_IN_WINDOW_P
|
|
Define this to be an expression that is 1 if the given register is in
|
|
the window.
|
|
|
|
@item IBM6000_TARGET
|
|
@findex IBM6000_TARGET
|
|
Shows that we are configured for an IBM RS/6000 target. This
|
|
conditional should be eliminated (FIXME) and replaced by
|
|
feature-specific macros. It was introduced in a haste and we are
|
|
repenting at leisure.
|
|
|
|
@item SYMBOLS_CAN_START_WITH_DOLLAR
|
|
@findex SYMBOLS_CAN_START_WITH_DOLLAR
|
|
Some systems have routines whose names start with @samp{$}. Giving this
|
|
macro a non-zero value tells @value{GDBN}'s expression parser to check for such
|
|
routines when parsing tokens that begin with @samp{$}.
|
|
|
|
On HP-UX, certain system routines (millicode) have names beginning with
|
|
@samp{$} or @samp{$$}. For example, @code{$$dyncall} is a millicode
|
|
routine that handles inter-space procedure calls on PA-RISC.
|
|
|
|
@item IEEE_FLOAT
|
|
@findex IEEE_FLOAT
|
|
Define this if the target system uses IEEE-format floating point numbers.
|
|
|
|
@item INIT_EXTRA_FRAME_INFO (@var{fromleaf}, @var{frame})
|
|
@findex INIT_EXTRA_FRAME_INFO
|
|
If additional information about the frame is required this should be
|
|
stored in @code{frame->extra_info}. Space for @code{frame->extra_info}
|
|
is allocated using @code{frame_obstack_alloc}.
|
|
|
|
@item INIT_FRAME_PC (@var{fromleaf}, @var{prev})
|
|
@findex INIT_FRAME_PC
|
|
This is a C statement that sets the pc of the frame pointed to by
|
|
@var{prev}. [By default...]
|
|
|
|
@item INNER_THAN (@var{lhs}, @var{rhs})
|
|
@findex INNER_THAN
|
|
Returns non-zero if stack address @var{lhs} is inner than (nearer to the
|
|
stack top) stack address @var{rhs}. Define this as @code{lhs < rhs} if
|
|
the target's stack grows downward in memory, or @code{lhs > rsh} if the
|
|
stack grows upward.
|
|
|
|
@item IN_SIGTRAMP (@var{pc}, @var{name})
|
|
@findex IN_SIGTRAMP
|
|
Define this to return non-zero if the given @var{pc} and/or @var{name}
|
|
indicates that the current function is a @code{sigtramp}.
|
|
|
|
@item SIGTRAMP_START (@var{pc})
|
|
@findex SIGTRAMP_START
|
|
@itemx SIGTRAMP_END (@var{pc})
|
|
@findex SIGTRAMP_END
|
|
Define these to be the start and end address of the @code{sigtramp} for the
|
|
given @var{pc}. On machines where the address is just a compile time
|
|
constant, the macro expansion will typically just ignore the supplied
|
|
@var{pc}.
|
|
|
|
@item IN_SOLIB_CALL_TRAMPOLINE (@var{pc}, @var{name})
|
|
@findex IN_SOLIB_CALL_TRAMPOLINE
|
|
Define this to evaluate to nonzero if the program is stopped in the
|
|
trampoline that connects to a shared library.
|
|
|
|
@item IN_SOLIB_RETURN_TRAMPOLINE (@var{pc}, @var{name})
|
|
@findex IN_SOLIB_RETURN_TRAMPOLINE
|
|
Define this to evaluate to nonzero if the program is stopped in the
|
|
trampoline that returns from a shared library.
|
|
|
|
@item IN_SOLIB_DYNSYM_RESOLVE_CODE (@var{pc})
|
|
@findex IN_SOLIB_DYNSYM_RESOLVE_CODE
|
|
Define this to evaluate to nonzero if the program is stopped in the
|
|
dynamic linker.
|
|
|
|
@item SKIP_SOLIB_RESOLVER (@var{pc})
|
|
@findex SKIP_SOLIB_RESOLVER
|
|
Define this to evaluate to the (nonzero) address at which execution
|
|
should continue to get past the dynamic linker's symbol resolution
|
|
function. A zero value indicates that it is not important or necessary
|
|
to set a breakpoint to get through the dynamic linker and that single
|
|
stepping will suffice.
|
|
|
|
@item IS_TRAPPED_INTERNALVAR (@var{name})
|
|
@findex IS_TRAPPED_INTERNALVAR
|
|
This is an ugly hook to allow the specification of special actions that
|
|
should occur as a side-effect of setting the value of a variable
|
|
internal to @value{GDBN}. Currently only used by the h8500. Note that this
|
|
could be either a host or target conditional.
|
|
|
|
@item NEED_TEXT_START_END
|
|
@findex NEED_TEXT_START_END
|
|
Define this if @value{GDBN} should determine the start and end addresses of the
|
|
text section. (Seems dubious.)
|
|
|
|
@item NO_HIF_SUPPORT
|
|
@findex NO_HIF_SUPPORT
|
|
(Specific to the a29k.)
|
|
|
|
@item POINTER_TO_ADDRESS (@var{type}, @var{buf})
|
|
@findex POINTER_TO_ADDRESS
|
|
Assume that @var{buf} holds a pointer of type @var{type}, in the
|
|
appropriate format for the current architecture. Return the byte
|
|
address the pointer refers to.
|
|
@xref{Target Architecture Definition, , Pointers Are Not Always Addresses}.
|
|
|
|
@item REGISTER_CONVERTIBLE (@var{reg})
|
|
@findex REGISTER_CONVERTIBLE
|
|
Return non-zero if @var{reg} uses different raw and virtual formats.
|
|
@xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
|
|
|
|
@item REGISTER_RAW_SIZE (@var{reg})
|
|
@findex REGISTER_RAW_SIZE
|
|
Return the raw size of @var{reg}.
|
|
@xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
|
|
|
|
@item REGISTER_VIRTUAL_SIZE (@var{reg})
|
|
@findex REGISTER_VIRTUAL_SIZE
|
|
Return the virtual size of @var{reg}.
|
|
@xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
|
|
|
|
@item REGISTER_VIRTUAL_TYPE (@var{reg})
|
|
@findex REGISTER_VIRTUAL_TYPE
|
|
Return the virtual type of @var{reg}.
|
|
@xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
|
|
|
|
@item REGISTER_CONVERT_TO_VIRTUAL(@var{reg}, @var{type}, @var{from}, @var{to})
|
|
@findex REGISTER_CONVERT_TO_VIRTUAL
|
|
Convert the value of register @var{reg} from its raw form to its virtual
|
|
form.
|
|
@xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
|
|
|
|
@item REGISTER_CONVERT_TO_RAW(@var{type}, @var{reg}, @var{from}, @var{to})
|
|
@findex REGISTER_CONVERT_TO_RAW
|
|
Convert the value of register @var{reg} from its virtual form to its raw
|
|
form.
|
|
@xref{Target Architecture Definition, , Using Different Register and Memory Data Representations}.
|
|
|
|
@item RETURN_VALUE_ON_STACK(@var{type})
|
|
@findex RETURN_VALUE_ON_STACK
|
|
@cindex returning structures by value
|
|
@cindex structures, returning by value
|
|
|
|
Return non-zero if values of type TYPE are returned on the stack, using
|
|
the ``struct convention'' (i.e., the caller provides a pointer to a
|
|
buffer in which the callee should store the return value). This
|
|
controls how the @samp{finish} command finds a function's return value,
|
|
and whether an inferior function call reserves space on the stack for
|
|
the return value.
|
|
|
|
The full logic @value{GDBN} uses here is kind of odd.
|
|
|
|
@itemize @bullet
|
|
@item
|
|
If the type being returned by value is not a structure, union, or array,
|
|
and @code{RETURN_VALUE_ON_STACK} returns zero, then @value{GDBN}
|
|
concludes the value is not returned using the struct convention.
|
|
|
|
@item
|
|
Otherwise, @value{GDBN} calls @code{USE_STRUCT_CONVENTION} (see below).
|
|
If that returns non-zero, @value{GDBN} assumes the struct convention is
|
|
in use.
|
|
@end itemize
|
|
|
|
In other words, to indicate that a given type is returned by value using
|
|
the struct convention, that type must be either a struct, union, array,
|
|
or something @code{RETURN_VALUE_ON_STACK} likes, @emph{and} something
|
|
that @code{USE_STRUCT_CONVENTION} likes.
|
|
|
|
Note that, in C and C@t{++}, arrays are never returned by value. In those
|
|
languages, these predicates will always see a pointer type, never an
|
|
array type. All the references above to arrays being returned by value
|
|
apply only to other languages.
|
|
|
|
@item SOFTWARE_SINGLE_STEP_P
|
|
@findex SOFTWARE_SINGLE_STEP_P
|
|
Define this as 1 if the target does not have a hardware single-step
|
|
mechanism. The macro @code{SOFTWARE_SINGLE_STEP} must also be defined.
|
|
|
|
@item SOFTWARE_SINGLE_STEP(@var{signal}, @var{insert_breapoints_p})
|
|
@findex SOFTWARE_SINGLE_STEP
|
|
A function that inserts or removes (depending on
|
|
@var{insert_breapoints_p}) breakpoints at each possible destinations of
|
|
the next instruction. See @file{sparc-tdep.c} and @file{rs6000-tdep.c}
|
|
for examples.
|
|
|
|
@item SOFUN_ADDRESS_MAYBE_MISSING
|
|
@findex SOFUN_ADDRESS_MAYBE_MISSING
|
|
Somebody clever observed that, the more actual addresses you have in the
|
|
debug information, the more time the linker has to spend relocating
|
|
them. So whenever there's some other way the debugger could find the
|
|
address it needs, you should omit it from the debug info, to make
|
|
linking faster.
|
|
|
|
@code{SOFUN_ADDRESS_MAYBE_MISSING} indicates that a particular set of
|
|
hacks of this sort are in use, affecting @code{N_SO} and @code{N_FUN}
|
|
entries in stabs-format debugging information. @code{N_SO} stabs mark
|
|
the beginning and ending addresses of compilation units in the text
|
|
segment. @code{N_FUN} stabs mark the starts and ends of functions.
|
|
|
|
@code{SOFUN_ADDRESS_MAYBE_MISSING} means two things:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@code{N_FUN} stabs have an address of zero. Instead, you should find the
|
|
addresses where the function starts by taking the function name from
|
|
the stab, and then looking that up in the minsyms (the
|
|
linker/assembler symbol table). In other words, the stab has the
|
|
name, and the linker/assembler symbol table is the only place that carries
|
|
the address.
|
|
|
|
@item
|
|
@code{N_SO} stabs have an address of zero, too. You just look at the
|
|
@code{N_FUN} stabs that appear before and after the @code{N_SO} stab,
|
|
and guess the starting and ending addresses of the compilation unit from
|
|
them.
|
|
@end itemize
|
|
|
|
@item PCC_SOL_BROKEN
|
|
@findex PCC_SOL_BROKEN
|
|
(Used only in the Convex target.)
|
|
|
|
@item PC_IN_CALL_DUMMY
|
|
@findex PC_IN_CALL_DUMMY
|
|
See @file{inferior.h}.
|
|
|
|
@item PC_LOAD_SEGMENT
|
|
@findex PC_LOAD_SEGMENT
|
|
If defined, print information about the load segment for the program
|
|
counter. (Defined only for the RS/6000.)
|
|
|
|
@item PC_REGNUM
|
|
@findex PC_REGNUM
|
|
If the program counter is kept in a register, then define this macro to
|
|
be the number (greater than or equal to zero) of that register.
|
|
|
|
This should only need to be defined if @code{TARGET_READ_PC} and
|
|
@code{TARGET_WRITE_PC} are not defined.
|
|
|
|
@item NPC_REGNUM
|
|
@findex NPC_REGNUM
|
|
The number of the ``next program counter'' register, if defined.
|
|
|
|
@item NNPC_REGNUM
|
|
@findex NNPC_REGNUM
|
|
The number of the ``next next program counter'' register, if defined.
|
|
Currently, this is only defined for the Motorola 88K.
|
|
|
|
@item PARM_BOUNDARY
|
|
@findex PARM_BOUNDARY
|
|
If non-zero, round arguments to a boundary of this many bits before
|
|
pushing them on the stack.
|
|
|
|
@item PRINT_REGISTER_HOOK (@var{regno})
|
|
@findex PRINT_REGISTER_HOOK
|
|
If defined, this must be a function that prints the contents of the
|
|
given register to standard output.
|
|
|
|
@item PRINT_TYPELESS_INTEGER
|
|
@findex PRINT_TYPELESS_INTEGER
|
|
This is an obscure substitute for @code{print_longest} that seems to
|
|
have been defined for the Convex target.
|
|
|
|
@item PROCESS_LINENUMBER_HOOK
|
|
@findex PROCESS_LINENUMBER_HOOK
|
|
A hook defined for XCOFF reading.
|
|
|
|
@item PROLOGUE_FIRSTLINE_OVERLAP
|
|
@findex PROLOGUE_FIRSTLINE_OVERLAP
|
|
(Only used in unsupported Convex configuration.)
|
|
|
|
@item PS_REGNUM
|
|
@findex PS_REGNUM
|
|
If defined, this is the number of the processor status register. (This
|
|
definition is only used in generic code when parsing "$ps".)
|
|
|
|
@item POP_FRAME
|
|
@findex POP_FRAME
|
|
@findex call_function_by_hand
|
|
@findex return_command
|
|
Used in @samp{call_function_by_hand} to remove an artificial stack
|
|
frame and in @samp{return_command} to remove a real stack frame.
|
|
|
|
@item PUSH_ARGUMENTS (@var{nargs}, @var{args}, @var{sp}, @var{struct_return}, @var{struct_addr})
|
|
@findex PUSH_ARGUMENTS
|
|
Define this to push arguments onto the stack for inferior function
|
|
call. Returns the updated stack pointer value.
|
|
|
|
@item PUSH_DUMMY_FRAME
|
|
@findex PUSH_DUMMY_FRAME
|
|
Used in @samp{call_function_by_hand} to create an artificial stack frame.
|
|
|
|
@item REGISTER_BYTES
|
|
@findex REGISTER_BYTES
|
|
The total amount of space needed to store @value{GDBN}'s copy of the machine's
|
|
register state.
|
|
|
|
@item REGISTER_NAME(@var{i})
|
|
@findex REGISTER_NAME
|
|
Return the name of register @var{i} as a string. May return @code{NULL}
|
|
or @code{NUL} to indicate that register @var{i} is not valid.
|
|
|
|
@item REGISTER_NAMES
|
|
@findex REGISTER_NAMES
|
|
Deprecated in favor of @code{REGISTER_NAME}.
|
|
|
|
@item REG_STRUCT_HAS_ADDR (@var{gcc_p}, @var{type})
|
|
@findex REG_STRUCT_HAS_ADDR
|
|
Define this to return 1 if the given type will be passed by pointer
|
|
rather than directly.
|
|
|
|
@item SAVE_DUMMY_FRAME_TOS (@var{sp})
|
|
@findex SAVE_DUMMY_FRAME_TOS
|
|
Used in @samp{call_function_by_hand} to notify the target dependent code
|
|
of the top-of-stack value that will be passed to the the inferior code.
|
|
This is the value of the @code{SP} after both the dummy frame and space
|
|
for parameters/results have been allocated on the stack.
|
|
|
|
@item SDB_REG_TO_REGNUM
|
|
@findex SDB_REG_TO_REGNUM
|
|
Define this to convert sdb register numbers into @value{GDBN} regnums. If not
|
|
defined, no conversion will be done.
|
|
|
|
@item SHIFT_INST_REGS
|
|
@findex SHIFT_INST_REGS
|
|
(Only used for m88k targets.)
|
|
|
|
@item SKIP_PERMANENT_BREAKPOINT
|
|
@findex SKIP_PERMANENT_BREAKPOINT
|
|
Advance the inferior's PC past a permanent breakpoint. @value{GDBN} normally
|
|
steps over a breakpoint by removing it, stepping one instruction, and
|
|
re-inserting the breakpoint. However, permanent breakpoints are
|
|
hardwired into the inferior, and can't be removed, so this strategy
|
|
doesn't work. Calling @code{SKIP_PERMANENT_BREAKPOINT} adjusts the processor's
|
|
state so that execution will resume just after the breakpoint. This
|
|
macro does the right thing even when the breakpoint is in the delay slot
|
|
of a branch or jump.
|
|
|
|
@item SKIP_PROLOGUE (@var{pc})
|
|
@findex SKIP_PROLOGUE
|
|
A C expression that returns the address of the ``real'' code beyond the
|
|
function entry prologue found at @var{pc}.
|
|
|
|
@item SKIP_PROLOGUE_FRAMELESS_P
|
|
@findex SKIP_PROLOGUE_FRAMELESS_P
|
|
A C expression that should behave similarly, but that can stop as soon
|
|
as the function is known to have a frame. If not defined,
|
|
@code{SKIP_PROLOGUE} will be used instead.
|
|
|
|
@item SKIP_TRAMPOLINE_CODE (@var{pc})
|
|
@findex SKIP_TRAMPOLINE_CODE
|
|
If the target machine has trampoline code that sits between callers and
|
|
the functions being called, then define this macro to return a new PC
|
|
that is at the start of the real function.
|
|
|
|
@item SP_REGNUM
|
|
@findex SP_REGNUM
|
|
If the stack-pointer is kept in a register, then define this macro to be
|
|
the number (greater than or equal to zero) of that register.
|
|
|
|
This should only need to be defined if @code{TARGET_WRITE_SP} and
|
|
@code{TARGET_WRITE_SP} are not defined.
|
|
|
|
@item STAB_REG_TO_REGNUM
|
|
@findex STAB_REG_TO_REGNUM
|
|
Define this to convert stab register numbers (as gotten from `r'
|
|
declarations) into @value{GDBN} regnums. If not defined, no conversion will be
|
|
done.
|
|
|
|
@item STACK_ALIGN (@var{addr})
|
|
@findex STACK_ALIGN
|
|
Define this to adjust the address to the alignment required for the
|
|
processor's stack.
|
|
|
|
@item STEP_SKIPS_DELAY (@var{addr})
|
|
@findex STEP_SKIPS_DELAY
|
|
Define this to return true if the address is of an instruction with a
|
|
delay slot. If a breakpoint has been placed in the instruction's delay
|
|
slot, @value{GDBN} will single-step over that instruction before resuming
|
|
normally. Currently only defined for the Mips.
|
|
|
|
@item STORE_RETURN_VALUE (@var{type}, @var{valbuf})
|
|
@findex STORE_RETURN_VALUE
|
|
A C expression that stores a function return value of type @var{type},
|
|
where @var{valbuf} is the address of the value to be stored.
|
|
|
|
@item SUN_FIXED_LBRAC_BUG
|
|
@findex SUN_FIXED_LBRAC_BUG
|
|
(Used only for Sun-3 and Sun-4 targets.)
|
|
|
|
@item SYMBOL_RELOADING_DEFAULT
|
|
@findex SYMBOL_RELOADING_DEFAULT
|
|
The default value of the ``symbol-reloading'' variable. (Never defined in
|
|
current sources.)
|
|
|
|
@item TARGET_BYTE_ORDER_DEFAULT
|
|
@findex TARGET_BYTE_ORDER_DEFAULT
|
|
The ordering of bytes in the target. This must be either
|
|
@code{BIG_ENDIAN} or @code{LITTLE_ENDIAN}. This macro replaces
|
|
@code{TARGET_BYTE_ORDER} which is deprecated.
|
|
|
|
@item TARGET_BYTE_ORDER_SELECTABLE_P
|
|
@findex TARGET_BYTE_ORDER_SELECTABLE_P
|
|
Non-zero if the target has both @code{BIG_ENDIAN} and
|
|
@code{LITTLE_ENDIAN} variants. This macro replaces
|
|
@code{TARGET_BYTE_ORDER_SELECTABLE} which is deprecated.
|
|
|
|
@item TARGET_CHAR_BIT
|
|
@findex TARGET_CHAR_BIT
|
|
Number of bits in a char; defaults to 8.
|
|
|
|
@item TARGET_COMPLEX_BIT
|
|
@findex TARGET_COMPLEX_BIT
|
|
Number of bits in a complex number; defaults to @code{2 * TARGET_FLOAT_BIT}.
|
|
|
|
At present this macro is not used.
|
|
|
|
@item TARGET_DOUBLE_BIT
|
|
@findex TARGET_DOUBLE_BIT
|
|
Number of bits in a double float; defaults to @code{8 * TARGET_CHAR_BIT}.
|
|
|
|
@item TARGET_DOUBLE_COMPLEX_BIT
|
|
@findex TARGET_DOUBLE_COMPLEX_BIT
|
|
Number of bits in a double complex; defaults to @code{2 * TARGET_DOUBLE_BIT}.
|
|
|
|
At present this macro is not used.
|
|
|
|
@item TARGET_FLOAT_BIT
|
|
@findex TARGET_FLOAT_BIT
|
|
Number of bits in a float; defaults to @code{4 * TARGET_CHAR_BIT}.
|
|
|
|
@item TARGET_INT_BIT
|
|
@findex TARGET_INT_BIT
|
|
Number of bits in an integer; defaults to @code{4 * TARGET_CHAR_BIT}.
|
|
|
|
@item TARGET_LONG_BIT
|
|
@findex TARGET_LONG_BIT
|
|
Number of bits in a long integer; defaults to @code{4 * TARGET_CHAR_BIT}.
|
|
|
|
@item TARGET_LONG_DOUBLE_BIT
|
|
@findex TARGET_LONG_DOUBLE_BIT
|
|
Number of bits in a long double float;
|
|
defaults to @code{2 * TARGET_DOUBLE_BIT}.
|
|
|
|
@item TARGET_LONG_LONG_BIT
|
|
@findex TARGET_LONG_LONG_BIT
|
|
Number of bits in a long long integer; defaults to @code{2 * TARGET_LONG_BIT}.
|
|
|
|
@item TARGET_PTR_BIT
|
|
@findex TARGET_PTR_BIT
|
|
Number of bits in a pointer; defaults to @code{TARGET_INT_BIT}.
|
|
|
|
@item TARGET_SHORT_BIT
|
|
@findex TARGET_SHORT_BIT
|
|
Number of bits in a short integer; defaults to @code{2 * TARGET_CHAR_BIT}.
|
|
|
|
@item TARGET_READ_PC
|
|
@findex TARGET_READ_PC
|
|
@itemx TARGET_WRITE_PC (@var{val}, @var{pid})
|
|
@findex TARGET_WRITE_PC
|
|
@itemx TARGET_READ_SP
|
|
@findex TARGET_READ_SP
|
|
@itemx TARGET_WRITE_SP
|
|
@findex TARGET_WRITE_SP
|
|
@itemx TARGET_READ_FP
|
|
@findex TARGET_READ_FP
|
|
@itemx TARGET_WRITE_FP
|
|
@findex TARGET_WRITE_FP
|
|
@findex read_pc
|
|
@findex write_pc
|
|
@findex read_sp
|
|
@findex write_sp
|
|
@findex read_fp
|
|
@findex write_fp
|
|
These change the behavior of @code{read_pc}, @code{write_pc},
|
|
@code{read_sp}, @code{write_sp}, @code{read_fp} and @code{write_fp}.
|
|
For most targets, these may be left undefined. @value{GDBN} will call the read
|
|
and write register functions with the relevant @code{_REGNUM} argument.
|
|
|
|
These macros are useful when a target keeps one of these registers in a
|
|
hard to get at place; for example, part in a segment register and part
|
|
in an ordinary register.
|
|
|
|
@item TARGET_VIRTUAL_FRAME_POINTER(@var{pc}, @var{regp}, @var{offsetp})
|
|
@findex TARGET_VIRTUAL_FRAME_POINTER
|
|
Returns a @code{(register, offset)} pair representing the virtual
|
|
frame pointer in use at the code address @var{pc}. If virtual
|
|
frame pointers are not used, a default definition simply returns
|
|
@code{FP_REGNUM}, with an offset of zero.
|
|
|
|
@item USE_STRUCT_CONVENTION (@var{gcc_p}, @var{type})
|
|
@findex USE_STRUCT_CONVENTION
|
|
If defined, this must be an expression that is nonzero if a value of the
|
|
given @var{type} being returned from a function must have space
|
|
allocated for it on the stack. @var{gcc_p} is true if the function
|
|
being considered is known to have been compiled by GCC; this is helpful
|
|
for systems where GCC is known to use different calling convention than
|
|
other compilers.
|
|
|
|
@item VARIABLES_INSIDE_BLOCK (@var{desc}, @var{gcc_p})
|
|
@findex VARIABLES_INSIDE_BLOCK
|
|
For dbx-style debugging information, if the compiler puts variable
|
|
declarations inside LBRAC/RBRAC blocks, this should be defined to be
|
|
nonzero. @var{desc} is the value of @code{n_desc} from the
|
|
@code{N_RBRAC} symbol, and @var{gcc_p} is true if @value{GDBN} has noticed the
|
|
presence of either the @code{GCC_COMPILED_SYMBOL} or the
|
|
@code{GCC2_COMPILED_SYMBOL}. By default, this is 0.
|
|
|
|
@item OS9K_VARIABLES_INSIDE_BLOCK (@var{desc}, @var{gcc_p})
|
|
@findex OS9K_VARIABLES_INSIDE_BLOCK
|
|
Similarly, for OS/9000. Defaults to 1.
|
|
@end table
|
|
|
|
Motorola M68K target conditionals.
|
|
|
|
@ftable @code
|
|
@item BPT_VECTOR
|
|
Define this to be the 4-bit location of the breakpoint trap vector. If
|
|
not defined, it will default to @code{0xf}.
|
|
|
|
@item REMOTE_BPT_VECTOR
|
|
Defaults to @code{1}.
|
|
@end ftable
|
|
|
|
@section Adding a New Target
|
|
|
|
@cindex adding a target
|
|
The following files define a target to @value{GDBN}:
|
|
|
|
@table @file
|
|
@vindex TDEPFILES
|
|
@item gdb/config/@var{arch}/@var{ttt}.mt
|
|
Contains a Makefile fragment specific to this target. Specifies what
|
|
object files are needed for target @var{ttt}, by defining
|
|
@samp{TDEPFILES=@dots{}} and @samp{TDEPLIBS=@dots{}}. Also specifies
|
|
the header file which describes @var{ttt}, by defining @samp{TM_FILE=
|
|
tm-@var{ttt}.h}.
|
|
|
|
You can also define @samp{TM_CFLAGS}, @samp{TM_CLIBS}, @samp{TM_CDEPS},
|
|
but these are now deprecated, replaced by autoconf, and may go away in
|
|
future versions of @value{GDBN}.
|
|
|
|
@item gdb/config/@var{arch}/tm-@var{ttt}.h
|
|
(@file{tm.h} is a link to this file, created by @code{configure}). Contains
|
|
macro definitions about the target machine's registers, stack frame
|
|
format and instructions.
|
|
|
|
@item gdb/@var{ttt}-tdep.c
|
|
Contains any miscellaneous code required for this target machine. On
|
|
some machines it doesn't exist at all. Sometimes the macros in
|
|
@file{tm-@var{ttt}.h} become very complicated, so they are implemented
|
|
as functions here instead, and the macro is simply defined to call the
|
|
function. This is vastly preferable, since it is easier to understand
|
|
and debug.
|
|
|
|
@item gdb/config/@var{arch}/tm-@var{arch}.h
|
|
This often exists to describe the basic layout of the target machine's
|
|
processor chip (registers, stack, etc.). If used, it is included by
|
|
@file{tm-@var{ttt}.h}. It can be shared among many targets that use the
|
|
same processor.
|
|
|
|
@item gdb/@var{arch}-tdep.c
|
|
Similarly, there are often common subroutines that are shared by all
|
|
target machines that use this particular architecture.
|
|
@end table
|
|
|
|
If you are adding a new operating system for an existing CPU chip, add a
|
|
@file{config/tm-@var{os}.h} file that describes the operating system
|
|
facilities that are unusual (extra symbol table info; the breakpoint
|
|
instruction needed; etc.). Then write a @file{@var{arch}/tm-@var{os}.h}
|
|
that just @code{#include}s @file{tm-@var{arch}.h} and
|
|
@file{config/tm-@var{os}.h}.
|
|
|
|
|
|
@node Target Vector Definition
|
|
|
|
@chapter Target Vector Definition
|
|
@cindex target vector
|
|
|
|
The target vector defines the interface between @value{GDBN}'s
|
|
abstract handling of target systems, and the nitty-gritty code that
|
|
actually exercises control over a process or a serial port.
|
|
@value{GDBN} includes some 30-40 different target vectors; however,
|
|
each configuration of @value{GDBN} includes only a few of them.
|
|
|
|
@section File Targets
|
|
|
|
Both executables and core files have target vectors.
|
|
|
|
@section Standard Protocol and Remote Stubs
|
|
|
|
@value{GDBN}'s file @file{remote.c} talks a serial protocol to code
|
|
that runs in the target system. @value{GDBN} provides several sample
|
|
@dfn{stubs} that can be integrated into target programs or operating
|
|
systems for this purpose; they are named @file{*-stub.c}.
|
|
|
|
The @value{GDBN} user's manual describes how to put such a stub into
|
|
your target code. What follows is a discussion of integrating the
|
|
SPARC stub into a complicated operating system (rather than a simple
|
|
program), by Stu Grossman, the author of this stub.
|
|
|
|
The trap handling code in the stub assumes the following upon entry to
|
|
@code{trap_low}:
|
|
|
|
@enumerate
|
|
@item
|
|
%l1 and %l2 contain pc and npc respectively at the time of the trap;
|
|
|
|
@item
|
|
traps are disabled;
|
|
|
|
@item
|
|
you are in the correct trap window.
|
|
@end enumerate
|
|
|
|
As long as your trap handler can guarantee those conditions, then there
|
|
is no reason why you shouldn't be able to ``share'' traps with the stub.
|
|
The stub has no requirement that it be jumped to directly from the
|
|
hardware trap vector. That is why it calls @code{exceptionHandler()},
|
|
which is provided by the external environment. For instance, this could
|
|
set up the hardware traps to actually execute code which calls the stub
|
|
first, and then transfers to its own trap handler.
|
|
|
|
For the most point, there probably won't be much of an issue with
|
|
``sharing'' traps, as the traps we use are usually not used by the kernel,
|
|
and often indicate unrecoverable error conditions. Anyway, this is all
|
|
controlled by a table, and is trivial to modify. The most important
|
|
trap for us is for @code{ta 1}. Without that, we can't single step or
|
|
do breakpoints. Everything else is unnecessary for the proper operation
|
|
of the debugger/stub.
|
|
|
|
From reading the stub, it's probably not obvious how breakpoints work.
|
|
They are simply done by deposit/examine operations from @value{GDBN}.
|
|
|
|
@section ROM Monitor Interface
|
|
|
|
@section Custom Protocols
|
|
|
|
@section Transport Layer
|
|
|
|
@section Builtin Simulator
|
|
|
|
|
|
@node Native Debugging
|
|
|
|
@chapter Native Debugging
|
|
@cindex native debugging
|
|
|
|
Several files control @value{GDBN}'s configuration for native support:
|
|
|
|
@table @file
|
|
@vindex NATDEPFILES
|
|
@item gdb/config/@var{arch}/@var{xyz}.mh
|
|
Specifies Makefile fragments needed when hosting @emph{or native} on
|
|
machine @var{xyz}. In particular, this lists the required
|
|
native-dependent object files, by defining @samp{NATDEPFILES=@dots{}}.
|
|
Also specifies the header file which describes native support on
|
|
@var{xyz}, by defining @samp{NAT_FILE= nm-@var{xyz}.h}. You can also
|
|
define @samp{NAT_CFLAGS}, @samp{NAT_ADD_FILES}, @samp{NAT_CLIBS},
|
|
@samp{NAT_CDEPS}, etc.; see @file{Makefile.in}.
|
|
|
|
@item gdb/config/@var{arch}/nm-@var{xyz}.h
|
|
(@file{nm.h} is a link to this file, created by @code{configure}). Contains C
|
|
macro definitions describing the native system environment, such as
|
|
child process control and core file support.
|
|
|
|
@item gdb/@var{xyz}-nat.c
|
|
Contains any miscellaneous C code required for this native support of
|
|
this machine. On some machines it doesn't exist at all.
|
|
@end table
|
|
|
|
There are some ``generic'' versions of routines that can be used by
|
|
various systems. These can be customized in various ways by macros
|
|
defined in your @file{nm-@var{xyz}.h} file. If these routines work for
|
|
the @var{xyz} host, you can just include the generic file's name (with
|
|
@samp{.o}, not @samp{.c}) in @code{NATDEPFILES}.
|
|
|
|
Otherwise, if your machine needs custom support routines, you will need
|
|
to write routines that perform the same functions as the generic file.
|
|
Put them into @file{@var{xyz}-nat.c}, and put @file{@var{xyz}-nat.o}
|
|
into @code{NATDEPFILES}.
|
|
|
|
@table @file
|
|
@item inftarg.c
|
|
This contains the @emph{target_ops vector} that supports Unix child
|
|
processes on systems which use ptrace and wait to control the child.
|
|
|
|
@item procfs.c
|
|
This contains the @emph{target_ops vector} that supports Unix child
|
|
processes on systems which use /proc to control the child.
|
|
|
|
@item fork-child.c
|
|
This does the low-level grunge that uses Unix system calls to do a ``fork
|
|
and exec'' to start up a child process.
|
|
|
|
@item infptrace.c
|
|
This is the low level interface to inferior processes for systems using
|
|
the Unix @code{ptrace} call in a vanilla way.
|
|
@end table
|
|
|
|
@section Native core file Support
|
|
@cindex native core files
|
|
|
|
@table @file
|
|
@findex fetch_core_registers
|
|
@item core-aout.c::fetch_core_registers()
|
|
Support for reading registers out of a core file. This routine calls
|
|
@code{register_addr()}, see below. Now that BFD is used to read core
|
|
files, virtually all machines should use @code{core-aout.c}, and should
|
|
just provide @code{fetch_core_registers} in @code{@var{xyz}-nat.c} (or
|
|
@code{REGISTER_U_ADDR} in @code{nm-@var{xyz}.h}).
|
|
|
|
@item core-aout.c::register_addr()
|
|
If your @code{nm-@var{xyz}.h} file defines the macro
|
|
@code{REGISTER_U_ADDR(addr, blockend, regno)}, it should be defined to
|
|
set @code{addr} to the offset within the @samp{user} struct of @value{GDBN}
|
|
register number @code{regno}. @code{blockend} is the offset within the
|
|
``upage'' of @code{u.u_ar0}. If @code{REGISTER_U_ADDR} is defined,
|
|
@file{core-aout.c} will define the @code{register_addr()} function and
|
|
use the macro in it. If you do not define @code{REGISTER_U_ADDR}, but
|
|
you are using the standard @code{fetch_core_registers()}, you will need
|
|
to define your own version of @code{register_addr()}, put it into your
|
|
@code{@var{xyz}-nat.c} file, and be sure @code{@var{xyz}-nat.o} is in
|
|
the @code{NATDEPFILES} list. If you have your own
|
|
@code{fetch_core_registers()}, you may not need a separate
|
|
@code{register_addr()}. Many custom @code{fetch_core_registers()}
|
|
implementations simply locate the registers themselves.@refill
|
|
@end table
|
|
|
|
When making @value{GDBN} run native on a new operating system, to make it
|
|
possible to debug core files, you will need to either write specific
|
|
code for parsing your OS's core files, or customize
|
|
@file{bfd/trad-core.c}. First, use whatever @code{#include} files your
|
|
machine uses to define the struct of registers that is accessible
|
|
(possibly in the u-area) in a core file (rather than
|
|
@file{machine/reg.h}), and an include file that defines whatever header
|
|
exists on a core file (e.g. the u-area or a @code{struct core}). Then
|
|
modify @code{trad_unix_core_file_p} to use these values to set up the
|
|
section information for the data segment, stack segment, any other
|
|
segments in the core file (perhaps shared library contents or control
|
|
information), ``registers'' segment, and if there are two discontiguous
|
|
sets of registers (e.g. integer and float), the ``reg2'' segment. This
|
|
section information basically delimits areas in the core file in a
|
|
standard way, which the section-reading routines in BFD know how to seek
|
|
around in.
|
|
|
|
Then back in @value{GDBN}, you need a matching routine called
|
|
@code{fetch_core_registers}. If you can use the generic one, it's in
|
|
@file{core-aout.c}; if not, it's in your @file{@var{xyz}-nat.c} file.
|
|
It will be passed a char pointer to the entire ``registers'' segment,
|
|
its length, and a zero; or a char pointer to the entire ``regs2''
|
|
segment, its length, and a 2. The routine should suck out the supplied
|
|
register values and install them into @value{GDBN}'s ``registers'' array.
|
|
|
|
If your system uses @file{/proc} to control processes, and uses ELF
|
|
format core files, then you may be able to use the same routines for
|
|
reading the registers out of processes and out of core files.
|
|
|
|
@section ptrace
|
|
|
|
@section /proc
|
|
|
|
@section win32
|
|
|
|
@section shared libraries
|
|
|
|
@section Native Conditionals
|
|
@cindex native conditionals
|
|
|
|
When @value{GDBN} is configured and compiled, various macros are
|
|
defined or left undefined, to control compilation when the host and
|
|
target systems are the same. These macros should be defined (or left
|
|
undefined) in @file{nm-@var{system}.h}.
|
|
|
|
@table @code
|
|
@item ATTACH_DETACH
|
|
@findex ATTACH_DETACH
|
|
If defined, then @value{GDBN} will include support for the @code{attach} and
|
|
@code{detach} commands.
|
|
|
|
@item CHILD_PREPARE_TO_STORE
|
|
@findex CHILD_PREPARE_TO_STORE
|
|
If the machine stores all registers at once in the child process, then
|
|
define this to ensure that all values are correct. This usually entails
|
|
a read from the child.
|
|
|
|
[Note that this is incorrectly defined in @file{xm-@var{system}.h} files
|
|
currently.]
|
|
|
|
@item FETCH_INFERIOR_REGISTERS
|
|
@findex FETCH_INFERIOR_REGISTERS
|
|
Define this if the native-dependent code will provide its own routines
|
|
@code{fetch_inferior_registers} and @code{store_inferior_registers} in
|
|
@file{@var{host}-nat.c}. If this symbol is @emph{not} defined, and
|
|
@file{infptrace.c} is included in this configuration, the default
|
|
routines in @file{infptrace.c} are used for these functions.
|
|
|
|
@item FILES_INFO_HOOK
|
|
@findex FILES_INFO_HOOK
|
|
(Only defined for Convex.)
|
|
|
|
@item FP0_REGNUM
|
|
@findex FP0_REGNUM
|
|
This macro is normally defined to be the number of the first floating
|
|
point register, if the machine has such registers. As such, it would
|
|
appear only in target-specific code. However, @file{/proc} support uses this
|
|
to decide whether floats are in use on this target.
|
|
|
|
@item GET_LONGJMP_TARGET
|
|
@findex GET_LONGJMP_TARGET
|
|
For most machines, this is a target-dependent parameter. On the
|
|
DECstation and the Iris, this is a native-dependent parameter, since
|
|
@file{setjmp.h} is needed to define it.
|
|
|
|
This macro determines the target PC address that @code{longjmp} will jump to,
|
|
assuming that we have just stopped at a longjmp breakpoint. It takes a
|
|
@code{CORE_ADDR *} as argument, and stores the target PC value through this
|
|
pointer. It examines the current state of the machine as needed.
|
|
|
|
@item KERNEL_U_ADDR
|
|
@findex KERNEL_U_ADDR
|
|
Define this to the address of the @code{u} structure (the ``user
|
|
struct'', also known as the ``u-page'') in kernel virtual memory. @value{GDBN}
|
|
needs to know this so that it can subtract this address from absolute
|
|
addresses in the upage, that are obtained via ptrace or from core files.
|
|
On systems that don't need this value, set it to zero.
|
|
|
|
@item KERNEL_U_ADDR_BSD
|
|
@findex KERNEL_U_ADDR_BSD
|
|
Define this to cause @value{GDBN} to determine the address of @code{u} at
|
|
runtime, by using Berkeley-style @code{nlist} on the kernel's image in
|
|
the root directory.
|
|
|
|
@item KERNEL_U_ADDR_HPUX
|
|
@findex KERNEL_U_ADDR_HPUX
|
|
Define this to cause @value{GDBN} to determine the address of @code{u} at
|
|
runtime, by using HP-style @code{nlist} on the kernel's image in the
|
|
root directory.
|
|
|
|
@item ONE_PROCESS_WRITETEXT
|
|
@findex ONE_PROCESS_WRITETEXT
|
|
Define this to be able to, when a breakpoint insertion fails, warn the
|
|
user that another process may be running with the same executable.
|
|
|
|
@item PREPARE_TO_PROCEED (@var{select_it})
|
|
@findex PREPARE_TO_PROCEED
|
|
This (ugly) macro allows a native configuration to customize the way the
|
|
@code{proceed} function in @file{infrun.c} deals with switching between
|
|
threads.
|
|
|
|
In a multi-threaded task we may select another thread and then continue
|
|
or step. But if the old thread was stopped at a breakpoint, it will
|
|
immediately cause another breakpoint stop without any execution (i.e. it
|
|
will report a breakpoint hit incorrectly). So @value{GDBN} must step over it
|
|
first.
|
|
|
|
If defined, @code{PREPARE_TO_PROCEED} should check the current thread
|
|
against the thread that reported the most recent event. If a step-over
|
|
is required, it returns TRUE. If @var{select_it} is non-zero, it should
|
|
reselect the old thread.
|
|
|
|
@item PROC_NAME_FMT
|
|
@findex PROC_NAME_FMT
|
|
Defines the format for the name of a @file{/proc} device. Should be
|
|
defined in @file{nm.h} @emph{only} in order to override the default
|
|
definition in @file{procfs.c}.
|
|
|
|
@item PTRACE_FP_BUG
|
|
@findex PTRACE_FP_BUG
|
|
See @file{mach386-xdep.c}.
|
|
|
|
@item PTRACE_ARG3_TYPE
|
|
@findex PTRACE_ARG3_TYPE
|
|
The type of the third argument to the @code{ptrace} system call, if it
|
|
exists and is different from @code{int}.
|
|
|
|
@item REGISTER_U_ADDR
|
|
@findex REGISTER_U_ADDR
|
|
Defines the offset of the registers in the ``u area''.
|
|
|
|
@item SHELL_COMMAND_CONCAT
|
|
@findex SHELL_COMMAND_CONCAT
|
|
If defined, is a string to prefix on the shell command used to start the
|
|
inferior.
|
|
|
|
@item SHELL_FILE
|
|
@findex SHELL_FILE
|
|
If defined, this is the name of the shell to use to run the inferior.
|
|
Defaults to @code{"/bin/sh"}.
|
|
|
|
@item SOLIB_ADD (@var{filename}, @var{from_tty}, @var{targ})
|
|
@findex SOLIB_ADD
|
|
Define this to expand into an expression that will cause the symbols in
|
|
@var{filename} to be added to @value{GDBN}'s symbol table.
|
|
|
|
@item SOLIB_CREATE_INFERIOR_HOOK
|
|
@findex SOLIB_CREATE_INFERIOR_HOOK
|
|
Define this to expand into any shared-library-relocation code that you
|
|
want to be run just after the child process has been forked.
|
|
|
|
@item START_INFERIOR_TRAPS_EXPECTED
|
|
@findex START_INFERIOR_TRAPS_EXPECTED
|
|
When starting an inferior, @value{GDBN} normally expects to trap
|
|
twice; once when
|
|
the shell execs, and once when the program itself execs. If the actual
|
|
number of traps is something other than 2, then define this macro to
|
|
expand into the number expected.
|
|
|
|
@item SVR4_SHARED_LIBS
|
|
@findex SVR4_SHARED_LIBS
|
|
Define this to indicate that SVR4-style shared libraries are in use.
|
|
|
|
@item USE_PROC_FS
|
|
@findex USE_PROC_FS
|
|
This determines whether small routines in @file{*-tdep.c}, which
|
|
translate register values between @value{GDBN}'s internal
|
|
representation and the @file{/proc} representation, are compiled.
|
|
|
|
@item U_REGS_OFFSET
|
|
@findex U_REGS_OFFSET
|
|
This is the offset of the registers in the upage. It need only be
|
|
defined if the generic ptrace register access routines in
|
|
@file{infptrace.c} are being used (that is, @file{infptrace.c} is
|
|
configured in, and @code{FETCH_INFERIOR_REGISTERS} is not defined). If
|
|
the default value from @file{infptrace.c} is good enough, leave it
|
|
undefined.
|
|
|
|
The default value means that u.u_ar0 @emph{points to} the location of
|
|
the registers. I'm guessing that @code{#define U_REGS_OFFSET 0} means
|
|
that @code{u.u_ar0} @emph{is} the location of the registers.
|
|
|
|
@item CLEAR_SOLIB
|
|
@findex CLEAR_SOLIB
|
|
See @file{objfiles.c}.
|
|
|
|
@item DEBUG_PTRACE
|
|
@findex DEBUG_PTRACE
|
|
Define this to debug @code{ptrace} calls.
|
|
@end table
|
|
|
|
|
|
@node Support Libraries
|
|
|
|
@chapter Support Libraries
|
|
|
|
@section BFD
|
|
@cindex BFD library
|
|
|
|
BFD provides support for @value{GDBN} in several ways:
|
|
|
|
@table @emph
|
|
@item identifying executable and core files
|
|
BFD will identify a variety of file types, including a.out, coff, and
|
|
several variants thereof, as well as several kinds of core files.
|
|
|
|
@item access to sections of files
|
|
BFD parses the file headers to determine the names, virtual addresses,
|
|
sizes, and file locations of all the various named sections in files
|
|
(such as the text section or the data section). @value{GDBN} simply
|
|
calls BFD to read or write section @var{x} at byte offset @var{y} for
|
|
length @var{z}.
|
|
|
|
@item specialized core file support
|
|
BFD provides routines to determine the failing command name stored in a
|
|
core file, the signal with which the program failed, and whether a core
|
|
file matches (i.e.@: could be a core dump of) a particular executable
|
|
file.
|
|
|
|
@item locating the symbol information
|
|
@value{GDBN} uses an internal interface of BFD to determine where to find the
|
|
symbol information in an executable file or symbol-file. @value{GDBN} itself
|
|
handles the reading of symbols, since BFD does not ``understand'' debug
|
|
symbols, but @value{GDBN} uses BFD's cached information to find the symbols,
|
|
string table, etc.
|
|
@end table
|
|
|
|
@section opcodes
|
|
@cindex opcodes library
|
|
|
|
The opcodes library provides @value{GDBN}'s disassembler. (It's a separate
|
|
library because it's also used in binutils, for @file{objdump}).
|
|
|
|
@section readline
|
|
|
|
@section mmalloc
|
|
|
|
@section libiberty
|
|
|
|
@section gnu-regex
|
|
@cindex regular expressions library
|
|
|
|
Regex conditionals.
|
|
|
|
@table @code
|
|
@item C_ALLOCA
|
|
|
|
@item NFAILURES
|
|
|
|
@item RE_NREGS
|
|
|
|
@item SIGN_EXTEND_CHAR
|
|
|
|
@item SWITCH_ENUM_BUG
|
|
|
|
@item SYNTAX_TABLE
|
|
|
|
@item Sword
|
|
|
|
@item sparc
|
|
@end table
|
|
|
|
@section include
|
|
|
|
@node Coding
|
|
|
|
@chapter Coding
|
|
|
|
This chapter covers topics that are lower-level than the major
|
|
algorithms of @value{GDBN}.
|
|
|
|
@section Cleanups
|
|
@cindex cleanups
|
|
|
|
Cleanups are a structured way to deal with things that need to be done
|
|
later. When your code does something (like @code{malloc} some memory,
|
|
or open a file) that needs to be undone later (e.g., free the memory or
|
|
close the file), it can make a cleanup. The cleanup will be done at
|
|
some future point: when the command is finished, when an error occurs,
|
|
or when your code decides it's time to do cleanups.
|
|
|
|
You can also discard cleanups, that is, throw them away without doing
|
|
what they say. This is only done if you ask that it be done.
|
|
|
|
Syntax:
|
|
|
|
@table @code
|
|
@item struct cleanup *@var{old_chain};
|
|
Declare a variable which will hold a cleanup chain handle.
|
|
|
|
@findex make_cleanup
|
|
@item @var{old_chain} = make_cleanup (@var{function}, @var{arg});
|
|
Make a cleanup which will cause @var{function} to be called with
|
|
@var{arg} (a @code{char *}) later. The result, @var{old_chain}, is a
|
|
handle that can be passed to @code{do_cleanups} or
|
|
@code{discard_cleanups} later. Unless you are going to call
|
|
@code{do_cleanups} or @code{discard_cleanups} yourself, you can ignore
|
|
the result from @code{make_cleanup}.
|
|
|
|
@findex do_cleanups
|
|
@item do_cleanups (@var{old_chain});
|
|
Perform all cleanups done since @code{make_cleanup} returned
|
|
@var{old_chain}. E.g.:
|
|
|
|
@example
|
|
make_cleanup (a, 0);
|
|
old = make_cleanup (b, 0);
|
|
do_cleanups (old);
|
|
@end example
|
|
|
|
@noindent
|
|
will call @code{b()} but will not call @code{a()}. The cleanup that
|
|
calls @code{a()} will remain in the cleanup chain, and will be done
|
|
later unless otherwise discarded.@refill
|
|
|
|
@findex discard_cleanups
|
|
@item discard_cleanups (@var{old_chain});
|
|
Same as @code{do_cleanups} except that it just removes the cleanups from
|
|
the chain and does not call the specified functions.
|
|
@end table
|
|
|
|
Some functions, e.g. @code{fputs_filtered()} or @code{error()}, specify
|
|
that they ``should not be called when cleanups are not in place''. This
|
|
means that any actions you need to reverse in the case of an error or
|
|
interruption must be on the cleanup chain before you call these
|
|
functions, since they might never return to your code (they
|
|
@samp{longjmp} instead).
|
|
|
|
@section Wrapping Output Lines
|
|
@cindex line wrap in output
|
|
|
|
@findex wrap_here
|
|
Output that goes through @code{printf_filtered} or @code{fputs_filtered}
|
|
or @code{fputs_demangled} needs only to have calls to @code{wrap_here}
|
|
added in places that would be good breaking points. The utility
|
|
routines will take care of actually wrapping if the line width is
|
|
exceeded.
|
|
|
|
The argument to @code{wrap_here} is an indentation string which is
|
|
printed @emph{only} if the line breaks there. This argument is saved
|
|
away and used later. It must remain valid until the next call to
|
|
@code{wrap_here} or until a newline has been printed through the
|
|
@code{*_filtered} functions. Don't pass in a local variable and then
|
|
return!
|
|
|
|
It is usually best to call @code{wrap_here} after printing a comma or
|
|
space. If you call it before printing a space, make sure that your
|
|
indentation properly accounts for the leading space that will print if
|
|
the line wraps there.
|
|
|
|
Any function or set of functions that produce filtered output must
|
|
finish by printing a newline, to flush the wrap buffer, before switching
|
|
to unfiltered (@code{printf}) output. Symbol reading routines that
|
|
print warnings are a good example.
|
|
|
|
@section @value{GDBN} Coding Standards
|
|
@cindex coding standards
|
|
|
|
@value{GDBN} follows the GNU coding standards, as described in
|
|
@file{etc/standards.texi}. This file is also available for anonymous
|
|
FTP from GNU archive sites. @value{GDBN} takes a strict interpretation of the
|
|
standard; in general, when the GNU standard recommends a practice but
|
|
does not require it, @value{GDBN} requires it.
|
|
|
|
@value{GDBN} follows an additional set of coding standards specific to
|
|
@value{GDBN}, as described in the following sections.
|
|
|
|
@cindex compiler warnings
|
|
You can configure with @samp{--enable-build-warnings} or
|
|
@samp{--enable-gdb-build-warnings} to get GCC to check on a number of
|
|
these rules. @value{GDBN} sources ought not to engender any complaints,
|
|
unless they are caused by bogus host systems. (The exact set of enabled
|
|
warnings is currently @samp{-Wimplicit -Wreturn-type -Wcomment
|
|
-Wtrigraphs -Wformat -Wparentheses -Wpointer-arith -Wuninitialized}.
|
|
|
|
@subsection Formatting
|
|
|
|
@cindex source code formatting
|
|
The standard GNU recommendations for formatting must be followed
|
|
strictly.
|
|
|
|
Note that while in a definition, the function's name must be in column
|
|
zero; in a function declaration, the name must be on the same line as
|
|
the return type.
|
|
|
|
In addition, there must be a space between a function or macro name and
|
|
the opening parenthesis of its argument list (except for macro
|
|
definitions, as required by C). There must not be a space after an open
|
|
paren/bracket or before a close paren/bracket.
|
|
|
|
While additional whitespace is generally helpful for reading, do not use
|
|
more than one blank line to separate blocks, and avoid adding whitespace
|
|
after the end of a program line (as of 1/99, some 600 lines had whitespace
|
|
after the semicolon). Excess whitespace causes difficulties for
|
|
@code{diff} and @code{patch} utilities.
|
|
|
|
@subsection Comments
|
|
|
|
@cindex comment formatting
|
|
The standard GNU requirements on comments must be followed strictly.
|
|
|
|
Block comments must appear in the following form, with no @samp{/*}- or
|
|
@samp{*/}-only lines, and no leading @samp{*}:
|
|
|
|
@example
|
|
/* Wait for control to return from inferior to debugger. If inferior
|
|
gets a signal, we may decide to start it up again instead of
|
|
returning. That is why there is a loop in this function. When
|
|
this function actually returns it means the inferior should be left
|
|
stopped and @value{GDBN} should read more commands. */
|
|
@end example
|
|
|
|
(Note that this format is encouraged by Emacs; tabbing for a multi-line
|
|
comment works correctly, and @kbd{M-q} fills the block consistently.)
|
|
|
|
Put a blank line between the block comments preceding function or
|
|
variable definitions, and the definition itself.
|
|
|
|
In general, put function-body comments on lines by themselves, rather
|
|
than trying to fit them into the 20 characters left at the end of a
|
|
line, since either the comment or the code will inevitably get longer
|
|
than will fit, and then somebody will have to move it anyhow.
|
|
|
|
@subsection C Usage
|
|
|
|
@cindex C data types
|
|
Code must not depend on the sizes of C data types, the format of the
|
|
host's floating point numbers, the alignment of anything, or the order
|
|
of evaluation of expressions.
|
|
|
|
@cindex function usage
|
|
Use functions freely. There are only a handful of compute-bound areas
|
|
in @value{GDBN} that might be affected by the overhead of a function
|
|
call, mainly in symbol reading. Most of @value{GDBN}'s performance is
|
|
limited by the target interface (whether serial line or system call).
|
|
|
|
However, use functions with moderation. A thousand one-line functions
|
|
are just as hard to understand as a single thousand-line function.
|
|
|
|
@subsection Function Prototypes
|
|
|
|
@cindex function prototypes
|
|
Prototypes must be used to @emph{declare} functions, and may be used
|
|
to @emph{define} them. Prototypes for @value{GDBN} functions must
|
|
include both the argument type and name, with the name matching that
|
|
used in the actual function definition.
|
|
|
|
All external functions should have a declaration in a header file that
|
|
callers include, except for @code{_initialize_*} functions, which must
|
|
be external so that @file{init.c} construction works, but shouldn't be
|
|
visible to random source files.
|
|
|
|
All static functions must be declared in a block near the top of the
|
|
source file.
|
|
|
|
@subsection Clean Design
|
|
|
|
@cindex design
|
|
In addition to getting the syntax right, there's the little question of
|
|
semantics. Some things are done in certain ways in @value{GDBN} because long
|
|
experience has shown that the more obvious ways caused various kinds of
|
|
trouble.
|
|
|
|
@cindex assumptions about targets
|
|
You can't assume the byte order of anything that comes from a target
|
|
(including @var{value}s, object files, and instructions). Such things
|
|
must be byte-swapped using @code{SWAP_TARGET_AND_HOST} in
|
|
@value{GDBN}, or one of the swap routines defined in @file{bfd.h},
|
|
such as @code{bfd_get_32}.
|
|
|
|
You can't assume that you know what interface is being used to talk to
|
|
the target system. All references to the target must go through the
|
|
current @code{target_ops} vector.
|
|
|
|
You can't assume that the host and target machines are the same machine
|
|
(except in the ``native'' support modules). In particular, you can't
|
|
assume that the target machine's header files will be available on the
|
|
host machine. Target code must bring along its own header files --
|
|
written from scratch or explicitly donated by their owner, to avoid
|
|
copyright problems.
|
|
|
|
@cindex portability
|
|
Insertion of new @code{#ifdef}'s will be frowned upon. It's much better
|
|
to write the code portably than to conditionalize it for various
|
|
systems.
|
|
|
|
@cindex system dependencies
|
|
New @code{#ifdef}'s which test for specific compilers or manufacturers
|
|
or operating systems are unacceptable. All @code{#ifdef}'s should test
|
|
for features. The information about which configurations contain which
|
|
features should be segregated into the configuration files. Experience
|
|
has proven far too often that a feature unique to one particular system
|
|
often creeps into other systems; and that a conditional based on some
|
|
predefined macro for your current system will become worthless over
|
|
time, as new versions of your system come out that behave differently
|
|
with regard to this feature.
|
|
|
|
Adding code that handles specific architectures, operating systems,
|
|
target interfaces, or hosts, is not acceptable in generic code. If a
|
|
hook is needed at that point, invent a generic hook and define it for
|
|
your configuration, with something like:
|
|
|
|
@example
|
|
#ifdef WRANGLE_SIGNALS
|
|
WRANGLE_SIGNALS (signo);
|
|
#endif
|
|
@end example
|
|
|
|
In your host, target, or native configuration file, as appropriate,
|
|
define @code{WRANGLE_SIGNALS} to do the machine-dependent thing. Take a
|
|
bit of care in defining the hook, so that it can be used by other ports
|
|
in the future, if they need a hook in the same place.
|
|
|
|
If the hook is not defined, the code should do whatever ``most'' machines
|
|
want. Using @code{#ifdef}, as above, is the preferred way to do this,
|
|
but sometimes that gets convoluted, in which case use
|
|
|
|
@example
|
|
#ifndef SPECIAL_FOO_HANDLING
|
|
#define SPECIAL_FOO_HANDLING(pc, sp) (0)
|
|
#endif
|
|
@end example
|
|
|
|
@noindent
|
|
where the macro is used or in an appropriate header file.
|
|
|
|
Whether to include a @dfn{small} hook, a hook around the exact pieces of
|
|
code which are system-dependent, or whether to replace a whole function
|
|
with a hook, depends on the case. A good example of this dilemma can be
|
|
found in @code{get_saved_register}. All machines that @value{GDBN} 2.8 ran on
|
|
just needed the @code{FRAME_FIND_SAVED_REGS} hook to find the saved
|
|
registers. Then the SPARC and Pyramid came along, and
|
|
@code{HAVE_REGISTER_WINDOWS} and @code{REGISTER_IN_WINDOW_P} were
|
|
introduced. Then the 29k and 88k required the @code{GET_SAVED_REGISTER}
|
|
hook. The first three are examples of small hooks; the latter replaces
|
|
a whole function. In this specific case, it is useful to have both
|
|
kinds; it would be a bad idea to replace all the uses of the small hooks
|
|
with @code{GET_SAVED_REGISTER}, since that would result in much
|
|
duplicated code. Other times, duplicating a few lines of code here or
|
|
there is much cleaner than introducing a large number of small hooks.
|
|
|
|
Another way to generalize @value{GDBN} along a particular interface is with an
|
|
attribute struct. For example, @value{GDBN} has been generalized to handle
|
|
multiple kinds of remote interfaces---not by @code{#ifdef}s everywhere, but
|
|
by defining the @code{target_ops} structure and having a current target (as
|
|
well as a stack of targets below it, for memory references). Whenever
|
|
something needs to be done that depends on which remote interface we are
|
|
using, a flag in the current target_ops structure is tested (e.g.,
|
|
@code{target_has_stack}), or a function is called through a pointer in the
|
|
current target_ops structure. In this way, when a new remote interface
|
|
is added, only one module needs to be touched---the one that actually
|
|
implements the new remote interface. Other examples of
|
|
attribute-structs are BFD access to multiple kinds of object file
|
|
formats, or @value{GDBN}'s access to multiple source languages.
|
|
|
|
Please avoid duplicating code. For example, in @value{GDBN} 3.x all
|
|
the code interfacing between @code{ptrace} and the rest of
|
|
@value{GDBN} was duplicated in @file{*-dep.c}, and so changing
|
|
something was very painful. In @value{GDBN} 4.x, these have all been
|
|
consolidated into @file{infptrace.c}. @file{infptrace.c} can deal
|
|
with variations between systems the same way any system-independent
|
|
file would (hooks, @code{#if defined}, etc.), and machines which are
|
|
radically different don't need to use @file{infptrace.c} at all.
|
|
|
|
Don't put debugging @code{printf}s in the code.
|
|
|
|
@node Porting GDB
|
|
|
|
@chapter Porting @value{GDBN}
|
|
@cindex porting to new machines
|
|
|
|
Most of the work in making @value{GDBN} compile on a new machine is in
|
|
specifying the configuration of the machine. This is done in a
|
|
dizzying variety of header files and configuration scripts, which we
|
|
hope to make more sensible soon. Let's say your new host is called an
|
|
@var{xyz} (e.g., @samp{sun4}), and its full three-part configuration
|
|
name is @code{@var{arch}-@var{xvend}-@var{xos}} (e.g.,
|
|
@samp{sparc-sun-sunos4}). In particular:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
In the top level directory, edit @file{config.sub} and add @var{arch},
|
|
@var{xvend}, and @var{xos} to the lists of supported architectures,
|
|
vendors, and operating systems near the bottom of the file. Also, add
|
|
@var{xyz} as an alias that maps to
|
|
@code{@var{arch}-@var{xvend}-@var{xos}}. You can test your changes by
|
|
running
|
|
|
|
@example
|
|
./config.sub @var{xyz}
|
|
@end example
|
|
|
|
@noindent
|
|
and
|
|
|
|
@example
|
|
./config.sub @code{@var{arch}-@var{xvend}-@var{xos}}
|
|
@end example
|
|
|
|
@noindent
|
|
which should both respond with @code{@var{arch}-@var{xvend}-@var{xos}}
|
|
and no error messages.
|
|
|
|
@noindent
|
|
You need to port BFD, if that hasn't been done already. Porting BFD is
|
|
beyond the scope of this manual.
|
|
|
|
@item
|
|
To configure @value{GDBN} itself, edit @file{gdb/configure.host} to recognize
|
|
your system and set @code{gdb_host} to @var{xyz}, and (unless your
|
|
desired target is already available) also edit @file{gdb/configure.tgt},
|
|
setting @code{gdb_target} to something appropriate (for instance,
|
|
@var{xyz}).
|
|
|
|
@item
|
|
Finally, you'll need to specify and define @value{GDBN}'s host-, native-, and
|
|
target-dependent @file{.h} and @file{.c} files used for your
|
|
configuration.
|
|
@end itemize
|
|
|
|
@section Configuring @value{GDBN} for Release
|
|
|
|
@cindex preparing a release
|
|
@cindex making a distribution tarball
|
|
From the top level directory (containing @file{gdb}, @file{bfd},
|
|
@file{libiberty}, and so on):
|
|
|
|
@example
|
|
make -f Makefile.in gdb.tar.gz
|
|
@end example
|
|
|
|
@noindent
|
|
This will properly configure, clean, rebuild any files that are
|
|
distributed pre-built (e.g. @file{c-exp.tab.c} or @file{refcard.ps}),
|
|
and will then make a tarfile. (If the top level directory has already
|
|
been configured, you can just do @code{make gdb.tar.gz} instead.)
|
|
|
|
This procedure requires:
|
|
|
|
@itemize @bullet
|
|
|
|
@item
|
|
symbolic links;
|
|
|
|
@item
|
|
@code{makeinfo} (texinfo2 level);
|
|
|
|
@item
|
|
@TeX{};
|
|
|
|
@item
|
|
@code{dvips};
|
|
|
|
@item
|
|
@code{yacc} or @code{bison}.
|
|
@end itemize
|
|
|
|
@noindent
|
|
@dots{} and the usual slew of utilities (@code{sed}, @code{tar}, etc.).
|
|
|
|
@subheading TEMPORARY RELEASE PROCEDURE FOR DOCUMENTATION
|
|
|
|
@file{gdb.texinfo} is currently marked up using the texinfo-2 macros,
|
|
which are not yet a default for anything (but we have to start using
|
|
them sometime).
|
|
|
|
For making paper, the only thing this implies is the right generation of
|
|
@file{texinfo.tex} needs to be included in the distribution.
|
|
|
|
For making info files, however, rather than duplicating the texinfo2
|
|
distribution, generate @file{gdb-all.texinfo} locally, and include the
|
|
files @file{gdb.info*} in the distribution. Note the plural;
|
|
@code{makeinfo} will split the document into one overall file and five
|
|
or so included files.
|
|
|
|
@node Testsuite
|
|
|
|
@chapter Testsuite
|
|
@cindex test suite
|
|
|
|
The testsuite is an important component of the @value{GDBN} package.
|
|
While it is always worthwhile to encourage user testing, in practice
|
|
this is rarely sufficient; users typically use only a small subset of
|
|
the available commands, and it has proven all too common for a change
|
|
to cause a significant regression that went unnoticed for some time.
|
|
|
|
The @value{GDBN} testsuite uses the DejaGNU testing framework.
|
|
DejaGNU is built using @code{Tcl} and @code{expect}. The tests
|
|
themselves are calls to various @code{Tcl} procs; the framework runs all the
|
|
procs and summarizes the passes and fails.
|
|
|
|
@section Using the Testsuite
|
|
|
|
@cindex running the test suite
|
|
To run the testsuite, simply go to the @value{GDBN} object directory (or to the
|
|
testsuite's objdir) and type @code{make check}. This just sets up some
|
|
environment variables and invokes DejaGNU's @code{runtest} script. While
|
|
the testsuite is running, you'll get mentions of which test file is in use,
|
|
and a mention of any unexpected passes or fails. When the testsuite is
|
|
finished, you'll get a summary that looks like this:
|
|
|
|
@example
|
|
=== gdb Summary ===
|
|
|
|
# of expected passes 6016
|
|
# of unexpected failures 58
|
|
# of unexpected successes 5
|
|
# of expected failures 183
|
|
# of unresolved testcases 3
|
|
# of untested testcases 5
|
|
@end example
|
|
|
|
The ideal test run consists of expected passes only; however, reality
|
|
conspires to keep us from this ideal. Unexpected failures indicate
|
|
real problems, whether in @value{GDBN} or in the testsuite. Expected
|
|
failures are still failures, but ones which have been decided are too
|
|
hard to deal with at the time; for instance, a test case might work
|
|
everywhere except on AIX, and there is no prospect of the AIX case
|
|
being fixed in the near future. Expected failures should not be added
|
|
lightly, since you may be masking serious bugs in @value{GDBN}.
|
|
Unexpected successes are expected fails that are passing for some
|
|
reason, while unresolved and untested cases often indicate some minor
|
|
catastrophe, such as the compiler being unable to deal with a test
|
|
program.
|
|
|
|
When making any significant change to @value{GDBN}, you should run the
|
|
testsuite before and after the change, to confirm that there are no
|
|
regressions. Note that truly complete testing would require that you
|
|
run the testsuite with all supported configurations and a variety of
|
|
compilers; however this is more than really necessary. In many cases
|
|
testing with a single configuration is sufficient. Other useful
|
|
options are to test one big-endian (Sparc) and one little-endian (x86)
|
|
host, a cross config with a builtin simulator (powerpc-eabi,
|
|
mips-elf), or a 64-bit host (Alpha).
|
|
|
|
If you add new functionality to @value{GDBN}, please consider adding
|
|
tests for it as well; this way future @value{GDBN} hackers can detect
|
|
and fix their changes that break the functionality you added.
|
|
Similarly, if you fix a bug that was not previously reported as a test
|
|
failure, please add a test case for it. Some cases are extremely
|
|
difficult to test, such as code that handles host OS failures or bugs
|
|
in particular versions of compilers, and it's OK not to try to write
|
|
tests for all of those.
|
|
|
|
@section Testsuite Organization
|
|
|
|
@cindex test suite organization
|
|
The testsuite is entirely contained in @file{gdb/testsuite}. While the
|
|
testsuite includes some makefiles and configury, these are very minimal,
|
|
and used for little besides cleaning up, since the tests themselves
|
|
handle the compilation of the programs that @value{GDBN} will run. The file
|
|
@file{testsuite/lib/gdb.exp} contains common utility procs useful for
|
|
all @value{GDBN} tests, while the directory @file{testsuite/config} contains
|
|
configuration-specific files, typically used for special-purpose
|
|
definitions of procs like @code{gdb_load} and @code{gdb_start}.
|
|
|
|
The tests themselves are to be found in @file{testsuite/gdb.*} and
|
|
subdirectories of those. The names of the test files must always end
|
|
with @file{.exp}. DejaGNU collects the test files by wildcarding
|
|
in the test directories, so both subdirectories and individual files
|
|
get chosen and run in alphabetical order.
|
|
|
|
The following table lists the main types of subdirectories and what they
|
|
are for. Since DejaGNU finds test files no matter where they are
|
|
located, and since each test file sets up its own compilation and
|
|
execution environment, this organization is simply for convenience and
|
|
intelligibility.
|
|
|
|
@table @file
|
|
@item gdb.base
|
|
This is the base testsuite. The tests in it should apply to all
|
|
configurations of @value{GDBN} (but generic native-only tests may live here).
|
|
The test programs should be in the subset of C that is valid K&R,
|
|
ANSI/ISO, and C++ (@code{#ifdef}s are allowed if necessary, for instance
|
|
for prototypes).
|
|
|
|
@item gdb.@var{lang}
|
|
Language-specific tests for any language @var{lang} besides C. Examples are
|
|
@file{gdb.c++} and @file{gdb.java}.
|
|
|
|
@item gdb.@var{platform}
|
|
Non-portable tests. The tests are specific to a specific configuration
|
|
(host or target), such as HP-UX or eCos. Example is @file{gdb.hp}, for
|
|
HP-UX.
|
|
|
|
@item gdb.@var{compiler}
|
|
Tests specific to a particular compiler. As of this writing (June
|
|
1999), there aren't currently any groups of tests in this category that
|
|
couldn't just as sensibly be made platform-specific, but one could
|
|
imagine a @file{gdb.gcc}, for tests of @value{GDBN}'s handling of GCC
|
|
extensions.
|
|
|
|
@item gdb.@var{subsystem}
|
|
Tests that exercise a specific @value{GDBN} subsystem in more depth. For
|
|
instance, @file{gdb.disasm} exercises various disassemblers, while
|
|
@file{gdb.stabs} tests pathways through the stabs symbol reader.
|
|
@end table
|
|
|
|
@section Writing Tests
|
|
@cindex writing tests
|
|
|
|
In many areas, the @value{GDBN} tests are already quite comprehensive; you
|
|
should be able to copy existing tests to handle new cases.
|
|
|
|
You should try to use @code{gdb_test} whenever possible, since it
|
|
includes cases to handle all the unexpected errors that might happen.
|
|
However, it doesn't cost anything to add new test procedures; for
|
|
instance, @file{gdb.base/exprs.exp} defines a @code{test_expr} that
|
|
calls @code{gdb_test} multiple times.
|
|
|
|
Only use @code{send_gdb} and @code{gdb_expect} when absolutely
|
|
necessary, such as when @value{GDBN} has several valid responses to a command.
|
|
|
|
The source language programs do @emph{not} need to be in a consistent
|
|
style. Since @value{GDBN} is used to debug programs written in many different
|
|
styles, it's worth having a mix of styles in the testsuite; for
|
|
instance, some @value{GDBN} bugs involving the display of source lines would
|
|
never manifest themselves if the programs used GNU coding style
|
|
uniformly.
|
|
|
|
@node Hints
|
|
|
|
@chapter Hints
|
|
|
|
Check the @file{README} file, it often has useful information that does not
|
|
appear anywhere else in the directory.
|
|
|
|
@menu
|
|
* Getting Started:: Getting started working on @value{GDBN}
|
|
* Debugging GDB:: Debugging @value{GDBN} with itself
|
|
@end menu
|
|
|
|
@node Getting Started,,, Hints
|
|
|
|
@section Getting Started
|
|
|
|
@value{GDBN} is a large and complicated program, and if you first starting to
|
|
work on it, it can be hard to know where to start. Fortunately, if you
|
|
know how to go about it, there are ways to figure out what is going on.
|
|
|
|
This manual, the @value{GDBN} Internals manual, has information which applies
|
|
generally to many parts of @value{GDBN}.
|
|
|
|
Information about particular functions or data structures are located in
|
|
comments with those functions or data structures. If you run across a
|
|
function or a global variable which does not have a comment correctly
|
|
explaining what is does, this can be thought of as a bug in @value{GDBN}; feel
|
|
free to submit a bug report, with a suggested comment if you can figure
|
|
out what the comment should say. If you find a comment which is
|
|
actually wrong, be especially sure to report that.
|
|
|
|
Comments explaining the function of macros defined in host, target, or
|
|
native dependent files can be in several places. Sometimes they are
|
|
repeated every place the macro is defined. Sometimes they are where the
|
|
macro is used. Sometimes there is a header file which supplies a
|
|
default definition of the macro, and the comment is there. This manual
|
|
also documents all the available macros.
|
|
@c (@pxref{Host Conditionals}, @pxref{Target
|
|
@c Conditionals}, @pxref{Native Conditionals}, and @pxref{Obsolete
|
|
@c Conditionals})
|
|
|
|
Start with the header files. Once you have some idea of how
|
|
@value{GDBN}'s internal symbol tables are stored (see @file{symtab.h},
|
|
@file{gdbtypes.h}), you will find it much easier to understand the
|
|
code which uses and creates those symbol tables.
|
|
|
|
You may wish to process the information you are getting somehow, to
|
|
enhance your understanding of it. Summarize it, translate it to another
|
|
language, add some (perhaps trivial or non-useful) feature to @value{GDBN}, use
|
|
the code to predict what a test case would do and write the test case
|
|
and verify your prediction, etc. If you are reading code and your eyes
|
|
are starting to glaze over, this is a sign you need to use a more active
|
|
approach.
|
|
|
|
Once you have a part of @value{GDBN} to start with, you can find more
|
|
specifically the part you are looking for by stepping through each
|
|
function with the @code{next} command. Do not use @code{step} or you
|
|
will quickly get distracted; when the function you are stepping through
|
|
calls another function try only to get a big-picture understanding
|
|
(perhaps using the comment at the beginning of the function being
|
|
called) of what it does. This way you can identify which of the
|
|
functions being called by the function you are stepping through is the
|
|
one which you are interested in. You may need to examine the data
|
|
structures generated at each stage, with reference to the comments in
|
|
the header files explaining what the data structures are supposed to
|
|
look like.
|
|
|
|
Of course, this same technique can be used if you are just reading the
|
|
code, rather than actually stepping through it. The same general
|
|
principle applies---when the code you are looking at calls something
|
|
else, just try to understand generally what the code being called does,
|
|
rather than worrying about all its details.
|
|
|
|
@cindex command implementation
|
|
A good place to start when tracking down some particular area is with
|
|
a command which invokes that feature. Suppose you want to know how
|
|
single-stepping works. As a @value{GDBN} user, you know that the
|
|
@code{step} command invokes single-stepping. The command is invoked
|
|
via command tables (see @file{command.h}); by convention the function
|
|
which actually performs the command is formed by taking the name of
|
|
the command and adding @samp{_command}, or in the case of an
|
|
@code{info} subcommand, @samp{_info}. For example, the @code{step}
|
|
command invokes the @code{step_command} function and the @code{info
|
|
display} command invokes @code{display_info}. When this convention is
|
|
not followed, you might have to use @code{grep} or @kbd{M-x
|
|
tags-search} in emacs, or run @value{GDBN} on itself and set a
|
|
breakpoint in @code{execute_command}.
|
|
|
|
@cindex @code{bug-gdb} mailing list
|
|
If all of the above fail, it may be appropriate to ask for information
|
|
on @code{bug-gdb}. But @emph{never} post a generic question like ``I was
|
|
wondering if anyone could give me some tips about understanding
|
|
@value{GDBN}''---if we had some magic secret we would put it in this manual.
|
|
Suggestions for improving the manual are always welcome, of course.
|
|
|
|
@node Debugging GDB,,,Hints
|
|
|
|
@section Debugging @value{GDBN} with itself
|
|
@cindex debugging @value{GDBN}
|
|
|
|
If @value{GDBN} is limping on your machine, this is the preferred way to get it
|
|
fully functional. Be warned that in some ancient Unix systems, like
|
|
Ultrix 4.2, a program can't be running in one process while it is being
|
|
debugged in another. Rather than typing the command @kbd{@w{./gdb
|
|
./gdb}}, which works on Suns and such, you can copy @file{gdb} to
|
|
@file{gdb2} and then type @kbd{@w{./gdb ./gdb2}}.
|
|
|
|
When you run @value{GDBN} in the @value{GDBN} source directory, it will read a
|
|
@file{.gdbinit} file that sets up some simple things to make debugging
|
|
gdb easier. The @code{info} command, when executed without a subcommand
|
|
in a @value{GDBN} being debugged by gdb, will pop you back up to the top level
|
|
gdb. See @file{.gdbinit} for details.
|
|
|
|
If you use emacs, you will probably want to do a @code{make TAGS} after
|
|
you configure your distribution; this will put the machine dependent
|
|
routines for your local machine where they will be accessed first by
|
|
@kbd{M-.}
|
|
|
|
Also, make sure that you've either compiled @value{GDBN} with your local cc, or
|
|
have run @code{fixincludes} if you are compiling with gcc.
|
|
|
|
@section Submitting Patches
|
|
|
|
@cindex submitting patches
|
|
Thanks for thinking of offering your changes back to the community of
|
|
@value{GDBN} users. In general we like to get well designed enhancements.
|
|
Thanks also for checking in advance about the best way to transfer the
|
|
changes.
|
|
|
|
The @value{GDBN} maintainers will only install ``cleanly designed'' patches.
|
|
This manual summarizes what we believe to be clean design for @value{GDBN}.
|
|
|
|
If the maintainers don't have time to put the patch in when it arrives,
|
|
or if there is any question about a patch, it goes into a large queue
|
|
with everyone else's patches and bug reports.
|
|
|
|
@cindex legal papers for code contributions
|
|
The legal issue is that to incorporate substantial changes requires a
|
|
copyright assignment from you and/or your employer, granting ownership
|
|
of the changes to the Free Software Foundation. You can get the
|
|
standard documents for doing this by sending mail to @code{gnu@@gnu.org}
|
|
and asking for it. We recommend that people write in "All programs
|
|
owned by the Free Software Foundation" as "NAME OF PROGRAM", so that
|
|
changes in many programs (not just @value{GDBN}, but GAS, Emacs, GCC,
|
|
etc) can be
|
|
contributed with only one piece of legalese pushed through the
|
|
bureacracy and filed with the FSF. We can't start merging changes until
|
|
this paperwork is received by the FSF (their rules, which we follow
|
|
since we maintain it for them).
|
|
|
|
Technically, the easiest way to receive changes is to receive each
|
|
feature as a small context diff or unidiff, suitable for @code{patch}.
|
|
Each message sent to me should include the changes to C code and
|
|
header files for a single feature, plus @file{ChangeLog} entries for
|
|
each directory where files were modified, and diffs for any changes
|
|
needed to the manuals (@file{gdb/doc/gdb.texinfo} or
|
|
@file{gdb/doc/gdbint.texinfo}). If there are a lot of changes for a
|
|
single feature, they can be split down into multiple messages.
|
|
|
|
In this way, if we read and like the feature, we can add it to the
|
|
sources with a single patch command, do some testing, and check it in.
|
|
If you leave out the @file{ChangeLog}, we have to write one. If you leave
|
|
out the doc, we have to puzzle out what needs documenting. Etc., etc.
|
|
|
|
The reason to send each change in a separate message is that we will not
|
|
install some of the changes. They'll be returned to you with questions
|
|
or comments. If we're doing our job correctly, the message back to you
|
|
will say what you have to fix in order to make the change acceptable.
|
|
The reason to have separate messages for separate features is so that
|
|
the acceptable changes can be installed while one or more changes are
|
|
being reworked. If multiple features are sent in a single message, we
|
|
tend to not put in the effort to sort out the acceptable changes from
|
|
the unacceptable, so none of the features get installed until all are
|
|
acceptable.
|
|
|
|
If this sounds painful or authoritarian, well, it is. But we get a lot
|
|
of bug reports and a lot of patches, and many of them don't get
|
|
installed because we don't have the time to finish the job that the bug
|
|
reporter or the contributor could have done. Patches that arrive
|
|
complete, working, and well designed, tend to get installed on the day
|
|
they arrive. The others go into a queue and get installed as time
|
|
permits, which, since the maintainers have many demands to meet, may not
|
|
be for quite some time.
|
|
|
|
Please send patches directly to
|
|
@email{gdb-patches@@sourceware.cygnus.com, the @value{GDBN} maintainers}.
|
|
|
|
@section Obsolete Conditionals
|
|
@cindex obsolete code
|
|
|
|
Fragments of old code in @value{GDBN} sometimes reference or set the following
|
|
configuration macros. They should not be used by new code, and old uses
|
|
should be removed as those parts of the debugger are otherwise touched.
|
|
|
|
@table @code
|
|
@item STACK_END_ADDR
|
|
This macro used to define where the end of the stack appeared, for use
|
|
in interpreting core file formats that don't record this address in the
|
|
core file itself. This information is now configured in BFD, and @value{GDBN}
|
|
gets the info portably from there. The values in @value{GDBN}'s configuration
|
|
files should be moved into BFD configuration files (if needed there),
|
|
and deleted from all of @value{GDBN}'s config files.
|
|
|
|
Any @file{@var{foo}-xdep.c} file that references STACK_END_ADDR
|
|
is so old that it has never been converted to use BFD. Now that's old!
|
|
|
|
@item PYRAMID_CONTROL_FRAME_DEBUGGING
|
|
pyr-xdep.c
|
|
@item PYRAMID_CORE
|
|
pyr-xdep.c
|
|
@item PYRAMID_PTRACE
|
|
pyr-xdep.c
|
|
|
|
@item REG_STACK_SEGMENT
|
|
exec.c
|
|
|
|
@end table
|
|
|
|
@node Index
|
|
@unnumbered Index
|
|
|
|
@printindex cp
|
|
|
|
@c TeX can handle the contents at the start but makeinfo 3.12 can not
|
|
@ifinfo
|
|
@contents
|
|
@end ifinfo
|
|
@ifhtml
|
|
@contents
|
|
@end ifhtml
|
|
|
|
@bye
|