Thomas Gleixner wrote:
> While testing various kernel configs we found out that the problem
> comes and goes. Finally I started to compare the gcc command line
> options and after some fiddling it turned out that the following
> minimal deltas change the code generator behaviour:
>
> Bad: -march=pentium-mmx -Wa,-mtune=generic32
> Good: -march=i686 -mtune=generic -Wa,-mtune=generic32
> Good: -march=pentium-mmx -mtune-generic -Wa,-mtune=generic32
>
> I'm not supposed to understand the logic behind that, right ?
I don't either. I'm seeing:
timer_stats_update_stats:
timer_stats_update_stats:
pushl %edi <
leal 8(%esp), %edi <
andl $-16, %esp <
pushl -4(%edi) <
pushl %ebp pushl
%ebp
movl %esp, %ebp movl
%esp, %ebp
pushl %edi | andl
$-16, %esp
pushl %esi | subl
$112, %esp
pushl %ebx | movl
%ebx, 100(%esp)
subl $108, %esp | movl
%esi, 104(%esp)
> movl
%edi, 108(%esp)
call mcount call
mcount
where the only difference is -mtune=generic. I'm investigating.
Andrew.
