On 11/25/2009 08:44 AM, Jakub Jelinek wrote:
>
> If you compile kernels 90%+ people out there run with -p on i?86/x86_64,
> then certainly coming up with a new gcc switch and new profiling ABI is
> desirable. -p on i?86/x86_64 e.g. forces -fno-omit-frame-pointer, which
> makes code on these register starved arches significantly worse.
> Making GCC output profiling call before prologue instead of after prologue
> is a 4 liner in generic code and a few lines in target specific code.
> The important thing is that we shouldn't have 100 different profiling ABIs,
> so it is desirable to agree on something that will be generally useful not
> just for the kernel, but perhaps for other purposes.
>
There is really just one that makes sense, which is providing the
ABI-defined entry state, which means intercepting at the point of entry.
Anything else is/was a mistake.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
