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Re: [patch, arm] Consistent display of registers in corefile
- From: Mark Kettenis <mark dot kettenis at xs4all dot nl>
- To: yao at codesourcery dot com
- Cc: gdb-patches at sourceware dot org
- Date: Fri, 10 Dec 2010 15:43:15 +0100 (CET)
- Subject: Re: [patch, arm] Consistent display of registers in corefile
- References: <4D022D1A.7030701@codesourcery.com>
> Date: Fri, 10 Dec 2010 21:37:30 +0800
> From: Yao Qi <yao@codesourcery.com>
>
> GDB trunk has a test failure on ARM,
>
> FAIL: gdb.base/gcore.exp: corefile restored general registers
>
> In short, this failure is caused by output of 'info registers' before
> coredump doesn't match output of 'info registers' when corefole is
> loaded again, there are mainly two differences, [1] and [2].
>
> Output before coredump,
> r0 0x12008 73736^M
> r1 0xbea1f0c0 -1096683328^M
> [...]
> sp 0xbea1f0a4 0xbea1f0a4^M
> lr 0x849b 33947^M
> pc 0x83fc 0x83fc <terminal_func+4>^M
> cpsr 0x20000030 536870960^M
>
> Output when corefile is loaded,
> r0 0x12008 73736^M
> r1 0xbea1f0c0 3198283968^M // <---- [1]
> [...]
> sp 0xbea1f0a4 0xbea1f0a4^M
> lr 0x849b 33947^M
> pc 0x83fc 0x83fc <terminal_func+4>^M
> fps 0x727a622f 1920623151^M // <---- [2]
> cpsr 0x20000030 536870960^M
>
> The difference [1] is caused by different register types, uint32 vs.
> int32. In tdesc, the type of general register is "int", while in
> arm_register_type, it is regarded as builtin_uint32. This can be fixed
> when register type is handled in a consistent way (in reg_type.patch).
>
> The difference [2] is about displaying "fps" in output of "info
> registers". In default_register_reggroup_p, the group of register is
> determined by the type of register, which is not very precise. FPS
> should be in float group, but its type is INT. This can be fixed by
> defining ARM's own register_reggroup_p to override
> default_register_reggroup_p (in arm_fps_group.patch).
>
> Regression tested with combination of
> "\{-mthumb,-marm\}\{-fstack-protector,-fno-stack-protector}\{-march=armv7-a,-march=armv5t\}".
>
> OK for mainline?
I would suspect that the proper thing to do would be to align the
tdesc with the code instead of the other way around. The arm-core.xml
file seems to underspecify things by omitting the type=xxx clause on
many registers. Whoever wrote arm_register_type() at least had to
make a conscious decision about the signedness of the type used for
the general purpose registers.