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* ld.texinfo (ARM): Document --stub-group-size=N option.

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Move description of --pic-veneer option into the ARM section.
        * NEWS: Mention the support for long function calls.
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Nick Clifton 2008-05-21 08:09:38 +00:00
parent 3ce6fddb77
commit 726150b77a
3 changed files with 46 additions and 8 deletions
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7
ld/ChangeLog
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@ -1,3 +1,10 @@
2008-05-21 Christophe Lyon <christophe.lyon@st.com>
Nick Clifton <nickc@redhat.com>
* ld.texinfo (ARM): Document --stub-group-size=N option.
Move description of --pic-veneer option into the ARM section.
* NEWS: Mention the support for long function calls.
2008-05-15 Christophe Lyon <christophe.lyon@st.com>
* emultempl/armelf.em (build_section_lists): New function.

4
ld/NEWS
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@ -1,4 +1,8 @@
-*- text -*-
* The ARM ELF linker will now generate stubs for function calls to symbols that
are too far away. The placement of the stubs is controlled by a new linker
command line option: --stub-group-size=N.
Changes in 2.18:
* Linker sources now released under version 3 of the GNU General Public

43
ld/ld.texinfo
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@ -5505,13 +5505,6 @@ trampoline address instead of the function address. This is typically the
case when a pointer to a function is taken. The pointer will in fact
point to the function trampoline.
@cindex PIC_VENEER
@kindex --pic-veneer
The @samp{--pic-veneer} switch makes the linker use PIC sequences for
ARM/Thumb interworking veneers, even if the rest of the binary
is not PIC. This avoids problems on uClinux targets where
@samp{--emit-relocs} is used to generate relocatable binaries.
@ifclear GENERIC
@lowersections
@end ifclear
@ -5642,13 +5635,47 @@ are sufficient to avoid the erratum in both the scalar and vector cases.
@cindex NO_ENUM_SIZE_WARNING
@kindex --no-enum-size-warning
The @samp{--no-enum-size-warning} switch prevents the linker from
The @option{--no-enum-size-warning} switch prevents the linker from
warning when linking object files that specify incompatible EABI
enumeration size attributes. For example, with this switch enabled,
linking of an object file using 32-bit enumeration values with another
using enumeration values fitted into the smallest possible space will
not be diagnosed.
@cindex PIC_VENEER
@kindex --pic-veneer
The @samp{--pic-veneer} switch makes the linker use PIC sequences for
ARM/Thumb interworking veneers, even if the rest of the binary
is not PIC. This avoids problems on uClinux targets where
@samp{--emit-relocs} is used to generate relocatable binaries.
@cindex STUB_GROUP_SIZE
@kindex --stub-group-size=@var{N}
The linker will automatically generate and insert small sequences of
code into a linked ARM ELF executable whenever an attempt is made to
perform a function call to a symbol that is too far away. The
placement of these sequences of instructions - called stubs - is
controlled by the command line option @option{--stub-group-size=N}.
The placement is important because a poor choice can create a need for
duplicate stubs, increasing the code sizw. The linker will try to
group stubs together in order to reduce interruptions to the flow of
code, but it needs guidance as to how big these groups should be and
where they should be placed.
The value of @samp{N}, the parameter to the
@option{--stub-group-size=} option controls where the stub groups are
placed. If it is negative then all stubs are placed before the first
branch that needs them. If it is positive then the stubs can be
placed either before or after the branches that need them. If the
value of @samp{N} is 1 (either +1 or -1) then the linker will choose
exactly where to place groups of stubs, using its built in heuristics.
A value of @samp{N} greater than 1 (or smaller than -1) tells the
linker that a single group of stubs can service at most @samp{N} bytes
from the input sections.
The default, if @option{--stub-group-size=} is not specified, is
@samp{N = +1}.
@ifclear GENERIC
@lowersections
@end ifclear