Re: [Xen-devel] [Patch][0/2]implement dump_execution_state() on ia64

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 27/3/08 17:22, "Akio Takebe" <takebe_akio@xxxxxxxxxxxxxx> wrote:

>> There is already a function which does what you want (i.e., takes a
>> cpu_user_regs pointer) -- it's called show_execution_state().
>> 
>> On x86 we implement dump_execution_state() by forcing an exception (by
>> executing an invalid opcode) and dumping the calltrace from within the
>> exception handler. This works because the exception handler has a
>> cpu_user_regs pointer and hence can call show_execution_state(). We use the
>> same trick for handling BUG() and ASSERT(). The code concerned is in
>> arch/x86/traps.c:do_invalid_op().
> On x86, does "xm debug-key d" make system hang?
> Or it just uses the exception handler, not hangup?

It works fine. It uses dump_execution_state(), as you have seen when you
modified it, and hence it does indeed force an exception on each CPU in
turn, and the exception handler dumps the cpu_user_regs (also known as
'pt_regs' in ia64) pointer that it receives.

 -- Keir



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