Fixes a gdb segfault if a section named .opd is found in ELFv2 binaries.
* elf64-ppc.c (synthetic_opd): New static var.
(compare_symbols): Don't treat symbols in .opd specially for ELFv2.
(ppc64_elf_get_synthetic_symtab): Likewise. Comment.
This patch fixes imbalanced lwp_suspend/unsuspend calls caused by the
premature choosing of another event for fairness.
select_event_lwp would switch the event before a call to
unsuspend_all_lwps, thus it would be called with the wrong event.
This caused an assertion failure: unsuspend LWP xx, suspended=-1 when
testing gdb.threads/non-stop-fair-events.exp with ARM range stepping in
GDBServer.
This patch moves the switch of event after the unsuspend/unstop calls.
No regressions, tested on ubuntu 14.04 ARMv7 and x86.
With gdbserver-native.
gdb/gdbserver/ChangeLog:
* linux-low.c (linux_wait_1): Move event switch after unsuspend_lwps.
This patch replaces "keep things single" with "keep things simple".
gdb:
2016-08-31 Yao Qi <yao.qi@linaro.org>
* record-full.c (record_full_insert_breakpoint): Fix typo.
This patch adds a little more debug output, and replaces two variables
with one, tracking current max group size by group_size_ rather than
by has14_.
* powerpc.cc (class Stub_control): Delete stub14_group_size_
and has14_. Add group_size_.
(Stub_control::can_add_to_stub_group): Adjust to suit. Print
debug info when switching to adding sections before stubs.
Like 57f6d32d, this patch ensures that sections containing external
conditional branches limit the group size.
* elf64-ppc.c (group_sections): Delete stub14_group_size. Instead,
track max group size with a new "group_size" var that is reduced
by a factor of 1024 from the 24-bit branch size whenever a 14-bit
branch is seen.
ELF section sh_flags SHF_PPC_VLE was being set based on arch/mach,
which meant all code sections in an object file has the flag or all
lacked it. We can do better than that. Only those code sections
where VLE is enabled ought to have the flag, allowing an object file
to contain both VLE and non-VLE code.
Also, ELF header p_flags PF_PPC_VLE wasn't being set, and segments
were being split unnecessarily.
bfd/
* elf32-ppc.c (ppc_elf_section_processing): Delete.
(elf_backend_section_processing): Don't define.
(ppc_elf_modify_segment_map): Set p_flags and mark valid. Don't
split on non-exec sections differing in SHF_PPC_VLE. When
splitting segments, mark size invalid.
gas/
* config/tc-ppc.c (md_assemble): Set sh_flags for VLE. Test
ppc_cpu rather than calling ppc_mach to determine VLE mode.
(ppc_frag_check, ppc_handle_align): Likewise use ppc_cpu.
Variable "header" in function is set conditionally, but was accessed without
verifying if pointer was NULL.
opcodes/ChangeLog:
Cupertino Miranda <cmiranda@synopsys.com>
* opcodes/arc-dis.c (print_insn_arc): Changed.
This inserts missing parentheses in the calculation of the comparison
result between two different inferior numbers. The problem was found by
Philipp Rudo.
gdb/ChangeLog:
* thread.c (tp_array_compar): Insert missing parentheses.
gdb/testsuite/ChangeLog:
* gdb.multi/tids.exp: Test "thread apply all".
ld/ChangeLog:
Cupertino Miranda <cmiranda@synopsys.com>
* testsuite/ld-arc/tls_gs-01.d: Set to XFAIL on arc*-*-elf*.
* testsuite/ld-arc/tls_ie-01.d: Likewise.
PR gprof/20499
* corefile.c (num_of_syms_in): Return an unsigned int.
Fail if the count exceeds the maximum possible allocatable size.
(core_create_syms_from): Exit early if num_of_syms_in returns a
failure code.
PR gprof/20499
* corefile.c (num_of_syms_in): Return an unsigned int.
(core_create_syms_from): Catch a possible integer overflow
computing the argument to xmalloc. Also allow for the possibility
that an integer overflow in num_of_syms_in means that less space
has been allocated than expected.
This patch rewrites the rather obscure can_add_to_stub_group, fixing
a problem with the handling of sections containing conditional
external branches. When a section group contains any such section,
the group size needs to be limited to a much smaller size than groups
with only non-conditional external branches.
PR 20523
* powerpc.cc (class Stub_control): Add has14_. Comment owner_.
(Stub_control::can_add_to_stub_group): Correct grouping of
sections containing 14-bit external branches. When returning
false, set state_ to reflect the fact that we have one section
for the next group. Rewrite most of function for clarity.
Add and expand comments.
(Target_powerpc::do_relax): Print stub group size retry in hex.
Since the internal compression header size can be bigger than the
external compression header size, we should check the external
compression header size.
* readelf.c (load_specific_debug_section): Check the external
compression header size.
On i386, IFUNC function must be called via PLT. Since PLT in PIC
object uses EBX register, R_386_PLT32 relocation must be used to
call IFUNC function even when IFUNC function is defined locally.
Linker should issue an error when R_386_PC32 relocation is used
to call IFUNC function.
Since PR ld/19784 tests doesn't use PLT relocation to local IFUNC
function, they are moved to the x86-64 test directory.
bfd/
PR ld/14961
PR ld/20515
* elf32-i386.c (elf_i386_check_relocs): Issue an error when
R_386_PC32 relocation is used to call IFUNC function in PIC
object.
ld/
PR ld/14961
PR ld/20515
* testsuite/ld-i386/i386.exp: Run pr20515.
* testsuite/ld-i386/pr20515.d: New file.
* testsuite/ld-i386/pr20515.s: Likewise.
* testsuite/ld-ifunc/ifunc-14a.s: Use R_386_PLT32 to call IFUNC
function.
* testsuite/ld-ifunc/ifunc-14c.s: Likewise.
* testsuite/ld-ifunc/ifunc-2-i386.s: Likewise.
* testsuite/ld-ifunc/ifunc-2-local-i386.s: Likewise.
* testsuite/ld-ifunc/ifunc.exp: Move PR ld/19784 tests to ...
* testsuite/ld-x86-64/x86-64.exp: Here.
* testsuite/ld-ifunc/pr19784a.c: Moved to ...
* testsuite/ld-x86-64/pr19784a.c: Here.
* testsuite/ld-ifunc/pr19784b.c: Moved to ...
* testsuite/ld-x86-64/pr19784b.c: Here.
* testsuite/ld-ifunc/pr19784c.c: Moved to ...
* testsuite/ld-x86-64/pr19784c.c: Here.
gold/ChangeLog
2016-08-26 Han Shen <shenhan@google.com>
* powerpc.cc (Stub_table::min_size_threshold_): New member to
limit size.
(Stub_table::set_min_size_threshold): New member function.
(Stub_table::set_address_and_size): Add code to only allow size
increase.
(Target_powerpc::do_relax): Add code to record last size.
Commit 980aa3e6 was supposed to cure dyn_reloc counting problems, but
did the opposite. For PIC we count two types of dyn_reloc, those on
pc-relative relocs, and the total. If a sym needs pc-relative dyn
relocs then all the relocs are dynamic. If not, then only those that
are must_be_dyn_reloc are dynamic.
PR 20519
* elf64-ppc.c (pc_dynrelocs): New function.
(ppc64_elf_relocate_section): Use it and must_be_dyn_reloc to
handle pic dynamic relocs.
This patch fixes a typo in the mnemonic of the camellia_fl
instruction, which was implemented before as camellia_fi.
gas/ChangeLog:
2016-08-26 Jose E. Marchesi <jose.marchesi@oracle.com>
* testsuite/gas/sparc/crypto.d: Rename invalid opcode camellia_fi
to camellia_fl.
* testsuite/gas/sparc/crypto.s: Likewise.
opcodes/ChangeLog:
2016-08-26 Jose E. Marchesi <jose.marchesi@oracle.com>
* sparc-opc.c (sparc_opcodes): Fix typo in opcode, camellia_fi ->
camellia_fl.
2016-08-26 Thomas Preud'homme <thomas.preudhomme@arm.com>
bfd/
* bfd-in.h (struct elf32_arm_params): Define.
(bfd_elf32_arm_set_target_relocs): Rename into ...
(bfd_elf32_arm_set_target_params): This. Use a struct
elf32_arm_params to pass all parameters but the bfd and bfd_link_info.
* bfd-in2.h: Regenerate.
* elf32-arm.c (bfd_elf32_arm_set_target_relocs): Rename into ...
(bfd_elf32_arm_set_target_params): This. Pass all values via a struct
elf32_arm_params rather than as individual parameters.
ld/
* emultempl/armelf.em (params): New static variable.
(thumb_entry_symbol, byteswap_code, target1_is_rel, target2_type,
fix_v4bx, use_blx, vfp11_denorm_fix, stm32l4xx_fix, fix_cortex_a8,
no_enum_size_warning, no_wchar_size_warning, pic_veneer,
merge_exidx_entries, fix_arm1176, cmse_implib): move as part of the
above new structure.
(arm_elf_before_allocation): Access static variable from the params
structure.
(gld${EMULATION_NAME}_finish): Likewise.
(arm_elf_create_output_section_statements): Likewise and pass the
address of that structure to bfd_elf32_arm_set_target_relocs instead
of the static variables.
(PARSE_AND_LIST_ARGS_CASES): Access static variable from the params
structure.
bfd/
* elf32-arm.c (elf32_arm_get_stub_entry): Assert that we don't access
passed the end of htab->stub_group array.
(elf32_arm_create_or_find_stub_sec): Likewise.
(elf32_arm_create_stub): Likewise.
2016-08-26 Thomas Preud'homme <thomas.preudhomme@arm.com>
gas/
* config/tc-arm.c (v7m_psrs): Add MSPLIM, PSPLIM, MSPLIM_NS,
PSPLIM_NS, PRIMASK_NS, BASEPRI_NS, FAULTMASK_NS, CONTROL_NS, SP_NS and
their lowecase counterpart special registers. Write register
identifier in hex.
* testsuite/gas/arm/archv8m-cmse-msr.s: Reorganize tests per
operation, special register and then case. Use different register for
each operation. Add tests for new special registers.
* testsuite/gas/arm/archv8m-cmse-msr-base.d: Adapt expected result
accordingly.
* testsuite/gas/arm/archv8m-cmse-msr-main.d: Likewise.
* testsuite/gas/arm/archv8m-main-dsp-4.d: Likewise.
opcodes/
* arm-dis.c (psr_name): Use hex as case labels. Add detection for
MSPLIM, PSPLIM, MSPLIM_NS, PSPLIM_NS, PRIMASK_NS, BASEPRI_NS,
FAULTMASK_NS, CONTROL_NS and SP_NS special registers.
Forgot to set should_relocate to TRUE in case of GOT and TLS relocations of
undefined symbols for shared libraries.
In dynamic libraries if symbol is not known the instruction relocation would
not be resolved to point to the respective .got entry.
A test was created to detect similar future mistakes.
bfd/ChangeLog:
Cupertino Miranda <cmiranda@synopsys.com>
* elf32-arc.c (elf_arc_relocate_section): Changed. Set should_relocate
to TRUE for GOT and TLS relocs.
ld/ChangeLog:
Cupertino Miranda <cmiranda@synopsys.com>
* ld/testsuite/ld-arc/tls_gd-01.s: Added a testcase for this patch.
* ld/testsuite/ld-arc/tls_gd-01.d: Likewise.
ARC was overloading this options by forcing DT_INIT AND DT_FINI
to always point to _init and _fini, respectively.
bfd/ChangeLog:
Cupertino Miranda <cmiranda@synospsys.com>
* elf32-arc.c (elf_arc_finish_dynamic_sections): Changed.
Fixed conditions related to dynamic relocs relative offset patching.
Added arc_link_hash_table to be able to always generate and track
.rela.bss section.
bfd/ChangeLog:
Cupertino Miranda <cmiranda@synopsys.com>
* elf-bfd.h: Added ARC_ELF_DATA to enum elf_target_id.
* elf32-arc.c (struct elf_arc_link_hash_entry): Added.
(struct elf_arc_link_hash_table): Likewise.
(elf_arc_link_hash_newfunc): Likewise.
(elf_arc_link_hash_table_free): Likewise.
(arc_elf_link_hash_table_create): Likewise.
(elf_arc_relocate_section): Fixed conditions related to dynamic
(elf_arc_check_relocs): Likewise.
(arc_elf_create_dynamic_sections): Added
(elf_arc_adjust_dynamic_symbol): Changed access to .rela.bss to be done
through the hash table.
When no dynamic relocation was generated the .got content would not be
updated for the TLS_IE_GOT relocation addresses.
bfd/ChangeLog:
Cupertino Miranda <cmiranda@synopsys.com>
* arc-got.h (relocate_fix_got_relocs_for_got_info): Fixed addresses in
debug comments. Fixed address in .got related to TLS_IE_GOT dynamic
relocation.
ld/ChangeLog:
Cupertino Miranda <cmiranda@synopsys.com>
* testsuite/ld-arc/tls_ie-01.s: Added to verify associated fix.
* testsuite/ld-arc/tls_ie-01.d: Likewise
Added support for ARC_SDA_12 reloc.
Fixed ARC_N32_ME.
Added ME (middle-endian) to ARC_SDA_12 reloc.
bfd/ChangeLog:
Cupertino Miranda <cmiranda@synopsys.com>
* reloc.c: Fixed type in ARC_SECTOFF relocations. Added ARC_SDA_12
relocation.
* bfd-in2.h: Regenerated from the previous changes.
* libbfd.h: Regenerated from the previous changes.
include/ChangeLog:
Cupertino Miranda <cmiranda@synopsys.com>
* elf/arc-reloc.def: Fixed relocation formula for N*, SDA, SDA_12,
SDA_16_LD*, S13_PCREL, N32_ME, SECTOFF_* relocations.
* opcode/arc-func.h (replace_disp12s): Added. Used for SDA_12 relocation.
2016-08-26 Thomas Preud'homme <thomas.preudhomme@arm.com>
bfd/
* bfd-in.h (bfd_elf32_arm_set_target_relocs): Add a new parameter for
the input import library bfd.
* bfd-in2.h: Regenerate.
* elf32-arm.c (struct elf32_arm_link_hash_table): New in_implib_bfd
and new_cmse_stub_offset fields.
(stub_hash_newfunc): Initialize stub_offset and stub_template_size to
-1.
(elf32_arm_add_stub): Likewise for stub_offset.
(arm_new_stubs_start_offset_ptr): New function.
(arm_build_one_stub): Only allocate a stub_offset if it is -1. Allow
empty SG veneers to have zero relocations.
(arm_size_one_stub): Only initialize stub size and template
information for non empty veneers. Do not update veneer section size
if veneer already has an offset.
(elf32_arm_create_stub): Return the stub entry pointer or NULL instead
of a boolean indicating success or failure.
(cmse_scan): Change stub_changed parameter into an integer pointer
parameter cmse_stub_created to count the number of stub created and
adapt to change of return value in elf32_arm_create_stub.
(cmse_entry_fct_p): New function.
(arm_list_new_cmse_stub): Likewise.
(set_cmse_veneer_addr_from_implib): Likewise.
(elf32_arm_size_stubs): Define cmse_stub_created, pass its address to
cmse_scan instead of that of cmse_stub_changed to compute the number
of stub created and use it to initialize stub_changed. Call
set_cmse_veneer_addr_from_implib after all cmse_scan. Adapt to change
of return value in elf32_arm_create_stub. Use
arm_stub_section_start_offset () if not NULL to initialize size of
secure gateway veneers section. Initialize stub_offset of Cortex-A8
erratum fix to -1. Use ret to hold return value.
(elf32_arm_build_stubs): Use arm_stub_section_start_offset () if not
NULL to initialize size of secure gateway veneers section. Adapt
comment to stress the importance of zeroing veneer section content.
(bfd_elf32_arm_set_target_relocs): Add new in_implib_bfd parameter to
initialize eponymous field in struct elf32_arm_link_hash_table.
ld/
* emultempl/armelf.em (in_implib_filename): Declare and initialize new
variable.
(arm_elf_create_output_section_statements): Open import input library
file for writing and pass resulting in_implib_bfd to
bfd_elf32_arm_set_target_relocs.
(PARSE_AND_LIST_PROLOGUE): Define OPTION_IN_IMPLIB option.
(PARSE_AND_LIST_LONGOPTS): Define --in-implib option.
(PARSE_AND_LIST_OPTIONS): Add help message for --in-implib option.
(PARSE_AND_LIST_ARGS_CASES): Handle new OPTION_IN_IMPLIB case.
* ld.texinfo (--cmse-implib): Update to mention --in-implib.
(--in-implib): Document new option.
* NEWS: Likewise.
* testsuite/ld-arm/arm-elf.exp
(Secure gateway import library generation): add --defsym VER=1 to gas
CLI.
(Secure gateway import library generation: errors): Likewise.
(Input secure gateway import library): New test.
(Input secure gateway import library: no output import library):
Likewise.
(Input secure gateway import library: not an SG input import library):
Likewise.
(Input secure gateway import library: earlier stub section base):
Likewise.
(Input secure gateway import library: later stub section base):
Likewise.
(Input secure gateway import library: veneer comeback): Likewise.
(Input secure gateway import library: entry function change):
Likewise.
* testsuite/ld-arm/cmse-implib.s: Add input import library testing.
* testsuite/ld-arm/cmse-implib.rd: Update accordingly.
* testsuite/ld-arm/cmse-new-implib.out: New file.
* testsuite/ld-arm/cmse-new-implib.rd: Likewise.
* testsuite/ld-arm/cmse-new-implib-no-output.out: Likewise.
* testsuite/ld-arm/cmse-new-implib-not-sg-in-implib.out: Likewise.
* testsuite/ld-arm/cmse-new-earlier-later-implib.out: Likewise.
* testsuite/ld-arm/cmse-new-comeback-implib.rd: Likewise.
* testsuite/ld-arm/cmse-new-wrong-implib.out: Likewise.
This enhances the 32-bit and 64-bit s390 ELF backends with support for
reading and writing the core dump note sections NT_PRSTATUS and
NT_PRPSINFO. Byte swapping is done as appropriate, such that core files
can now be processed correctly on non-s390 platforms.
bfd/ChangeLog:
* elf32-s390.c (stdarg.h): New include.
(elf_s390_grok_psinfo): New function.
(elf_s390_write_core_note): New function.
(elf_backend_grok_psinfo): Declare backend hook.
(elf_backend_write_core_note): Likewise.
* elf64-s390.c (stdarg.h): New include.
(elf_s390_grok_prstatus): New function.
(elf_s390_grok_psinfo): New function.
(elf_s390_write_core_note): New function.
(elf_backend_grok_prstatus): Declare backend hook.
(elf_backend_grok_psinfo): Likewise.
(elf_backend_write_core_note): Likewise.
C++ does not officially support designators in initializer lists. Thus
some compilers may issue errors when encountering them. Modern versions
of GCC seem to allow them by default, as a GCC extension, even though
the GCC documentation explicitly states otherwise: "[...] This extension
is not implemented in GNU C++." But some older GCC versions (like
4.4.7) did indeed emit an error instead, like this:
.../gdb/xtensa-config.c:219: error: expected primary-expression before
‘.’ token
This patch removes the only such instance I've seen when building with
'--enable-targets=all'.
gdb/ChangeLog:
* xtensa-tdep.h (XTENSA_GDBARCH_TDEP_INSTANTIATE): Replace
designated initializer list by plain initializer list, for C++
compliance.
This fixes a few problems in the powerpc ld configury.
1) Using powerpc*le-* to test for powerpcle and powerpc64le would
incorrectly match a target triple like powerpc-apple-elf.
2) In the same vein, *64* could match 64 in the user supplied MANUF-OS
part of the target triple.
3) tooldir vars were missing, and some target aliases would result in
ridiculous values for those tdir_* vars given.
4) Since 2016-04-25, BE support was added automatically when asking
for an LE target. If that is a good idea, then so is adding LE
support when asking for BE.
* configure.tgt (powerpc*-*-linux* et al): Rewrite, adding LE
support for BE. First output all target endian configury
values, then opposite endian. Handle more tooldirs. Fix
bogus matches with strings in MANUF-OS part of target triple.
GLIBC BZ#20311 [1] proc_service.h install patch also remove 'const'
attributes from ps_get_thread_area and comment #15 discuss why to remove
the const attribute (basically since it a callback with the struct
ps_prochandle owned by the client it should be able to modify it if
it the case).
On default build this is not the issue and current g++ does not trigger
any issue with this mismatch declaration. However, on some bootstrap
build configuration where gdbserver is build with gcc instead this
triggers:
error: conflicting types for 'ps_get_thread_area'
This patch fixes it by syncing the declaration with GLIBC.
[1] https://sourceware.org/bugzilla/show_bug.cgi?id=20311
gdb/ChangeLog:
2016-08-25 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* aarch64-linux-nat.c (ps_get_thread_area): Remove const from
struct ps_prochandle.
* amd64-linux-nat.c (ps_get_thread_area): Likewise.
* arm-linux-nat.c (ps_get_thread_area): Likewise.
* gdb_proc_service.h (ps_get_thread_area): Likewise.
* i386-linux-nat.c (ps_get_thread_area): Likewise.
* m68klinux-nat.c (ps_get_thread_area): Likewise.
* mips-linux-nat.c (ps_get_thread_area): Likewise.
* nat/aarch64-linux.c (aarch64_ps_get_thread_area): Likewise.
* nat/aarch64-linux.h (aarch64_ps_get_thread_area): Likewise.
* xtensa-linux-nat.c (ps_get_thread_area): Likewise.
gdb/gdbserver/ChangeLog:
2016-08-25 Adhemerval Zanella <adhemerval.zanella@linaro.org>
PR server/20491
* gdb_proc_service.h (ps_get_thread_area): Remove const from struct
ps_prochandle.
* linux-aarch64-low.c (ps_get_thread_area): Likewise.
* linux-arm-low.c (ps_get_thread_area): Likewise.
* linux-crisv32-low.c (ps_get_thread_area): Likewise.
* linux-m68k-low.c (ps_get_thread_area): Likewise.
* linux-mips-low.c (ps_get_thread_area): Likewise.
* linux-nios2-low.c (ps_get_thread_area): Likewise.
* linux-tic6x-low.c (ps_get_thread_area): Likewise.
* linux-x86-low.c (ps_get_thread_area): Likewise.
* linux-xtensa-low.c (ps_get_thread_area): Likewise.
This test case verifies that GDB will not attempt to invoke a python
unwinder recursively.
At the moment, the behavior exhibited by GDB looks like this:
(gdb) source py-recurse-unwind.py
Python script imported
(gdb) b ccc
Breakpoint 1 at 0x4004bd: file py-recurse-unwind.c, line 23.
(gdb) run
Starting program: py-recurse-unwind
TestUnwinder: Recursion detected - returning early.
TestUnwinder: Recursion detected - returning early.
TestUnwinder: Recursion detected - returning early.
TestUnwinder: Recursion detected - returning early.
Breakpoint 1, ccc (arg=<unavailable>) at py-recurse-unwind.c:23
23 }
(gdb) bt
#-1 ccc (arg=<unavailable>) at py-recurse-unwind.c:23
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
[I've shortened pathnames for easier reading.]
The desired / expected behavior looks like this:
(gdb) source py-recurse-unwind.py
Python script imported
(gdb) b ccc
Breakpoint 1 at 0x4004bd: file py-recurse-unwind.c, line 23.
(gdb) run
Starting program: py-recurse-unwind
Breakpoint 1, ccc (arg=789) at py-recurse-unwind.c:23
23 }
(gdb) bt
#0 ccc (arg=789) at py-recurse-unwind.c:23
#1 0x00000000004004d5 in bbb (arg=456) at py-recurse-unwind.c:28
#2 0x00000000004004ed in aaa (arg=123) at py-recurse-unwind.c:34
#3 0x00000000004004fe in main () at py-recurse-unwind.c:40
Note that GDB's problems go well beyond the fact that it invokes the
unwinder recursively. In the process it messes up some internal state
(the frame stash) leading to display of (only) the sentinel frame in
the backtrace.
gdb/testsuite/ChangeLog:
* gdb.python/py-recurse-unwind.c: New file.
* gdb.python/py-recurse-unwind.py: New file.
* gdb.python/py-recurse-unwind.exp: New file.
This patch allows the user to set the inferior-tty to "empty", in order
to come back to the default behaviour of using the same tty as gdb is
using.
This is already supported in MI (and tested in gdb.mi/mi-basics.exp).
I added a new test, set-inferior-tty.exp, where I test only the setting
and unsetting of the parameter. It would be nice to actually test that
the inferior output properly goes to the separate tty, but that will be
for another day.
gdb/ChangeLog:
* infcmd.c (set_inferior_io_terminal): Set inferior terminal to
NULL if terminal_name is an empty string.
(_initialize_infcmd): Make the argument of "set inferior-tty"
optional, mention it in the help doc.
gdb/doc/ChangeLog:
* gdb.texinfo (Input/Output): Mention possibility to unset
inferior-tty.
gdb/testsuite/ChangeLog:
* gdb.base/set-inferior-tty.exp: New file.
* gdb.base/set-inferior-tty.c: New file.
