Re: [RFC PATCH v2] perf/x86: make perf callchain work without CONFIG_FRAME_POINTER

[Kairui Song]

On Wed, Apr 17, 2019 at 1:45 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Wed, Apr 17, 2019 at 01:39:19AM +0800, Kairui Song wrote:
> > And I also think the "fake"/"real" reg is fragile, could we abuse
> > another eflag (just like PERF_EFLAGS_EXACT) to indicate the regs are
> > partially dumped fake registers?
>
> Sure, the SDM seems to suggest bits 1,3,5,15 are 'available'. We've
> already used 3 and 5, and I think we can use !X86_EFLAGS_FIXED to
> indicate a fake regs set. Any real regs set will always have that set.

Thanks! This is a good idea. Will update accordingly in V3 later.





--
Best Regards,
Kairui Song