[sheepdog] [PATCH] util: dump ucontext in crash handlers

[MORITA Kazutaka]

At Wed,  1 May 2013 18:30:56 +0900,
Hitoshi Mitake wrote:
> 
> Current crash handlers (of sheep, collie, and logger) don't dump
> register status when the signal rises. This patch let them dump the
> information. I believe especially RIP is useful for debugging.

I don't thinks so.  If you are debugging Sheepdog on your environment,
you can get the register values from the core file.  If you are
debugging with a reported sheep.log from other environment, how does
the register status help us?

I cannot image the use case of RIP, too.  We can know where the
process crashed from the backtrace.  Why do we need it?

> 
> Example of output:
> May 01 18:23:07 [main] dump_mcontext(397) register status:
> May 01 18:23:07 [main] dump_mcontext(399) 	RIP: 0x4046ab
> May 01 18:23:07 [main] dump_mcontext(400) 	RSP: 0x7fff2ced9120
> May 01 18:23:07 [main] dump_mcontext(401) 	RBP: 0x1
> May 01 18:23:07 [main] dump_mcontext(402) 	RFLAGS: 0x10246
> May 01 18:23:07 [main] dump_mcontext(404) 	RAX: 0x5
> May 01 18:23:07 [main] dump_mcontext(405) 	RBX: 0x7fff2ceda348
> May 01 18:23:07 [main] dump_mcontext(406) 	RCX: 0x0
> May 01 18:23:07 [main] dump_mcontext(407) 	RDX: 0x0
> May 01 18:23:07 [main] dump_mcontext(408) 	R8: 0x7fff2ced8fd0
> May 01 18:23:07 [main] dump_mcontext(409) 	R9: 0x7f6fa31ef0e0
> May 01 18:23:07 [main] dump_mcontext(410) 	R10: 0x8
> May 01 18:23:07 [main] dump_mcontext(411) 	R11: 0x202
> May 01 18:23:07 [main] dump_mcontext(412) 	R12: 0x404050
> May 01 18:23:07 [main] dump_mcontext(413) 	R13: 0x7fff2ceda340
> May 01 18:23:07 [main] dump_mcontext(414) 	R14: 0x0
> May 01 18:23:07 [main] dump_mcontext(415) 	R15: 0x0
> May 01 18:23:07 [main] dump_mcontext(417) 	RDI: 0x42557d
> May 01 18:23:07 [main] dump_mcontext(418) 	RSI: 0x7fff2ced8f20

Does this work on i386 machines?

Thanks,

Kazutaka