* Mike Galbraith <umgwanakikb...@gmail.com> wrote:
> > This would suggest sensitivity on CPUID details, i.e. that doing
> > fpu__init_system() before other CPU init sequences is causing the bug.
> >
> > Does the patch below perhaps make a difference? (I'd suggest to apply it
> > _without_ the other patch I sent.)
>
> Yup, that made it not care about the BIOS setting.. again.
> > diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> > index 9fc5e3d9d9c8..922c5e0cea4c 100644
> > --- a/arch/x86/kernel/cpu/common.c
> > +++ b/arch/x86/kernel/cpu/common.c
> > @@ -742,7 +742,6 @@ static void __init early_identify_cpu(struct
> > cpuinfo_x86 *c)
> > cpu_detect(c);
> > get_cpu_vendor(c);
> > get_cpu_cap(c);
> > - fpu__init_system(c);
> >
> > if (this_cpu->c_early_init)
> > this_cpu->c_early_init(c);
> > @@ -754,6 +753,7 @@ static void __init early_identify_cpu(struct
> > cpuinfo_x86 *c)
> > this_cpu->c_bsp_init(c);
> >
> > setup_force_cpu_cap(X86_FEATURE_ALWAYS);
> > + fpu__init_system(c);
> > }
Ok, so could you please move the fpu__init_system() further up and see which
position is that starts breaking with the BIOS option set?
here's the current, broken layout of the code:
get_cpu_cap(c);
[0] fpu__init_system(c);
if (this_cpu->c_early_init)
this_cpu->c_early_init(c);
[1]
c->cpu_index = 0;
[2]
filter_cpuid_features(c, false);
[3]
if (this_cpu->c_bsp_init)
this_cpu->c_bsp_init(c);
[4]
setup_force_cpu_cap(X86_FEATURE_ALWAYS);
[5]
}
and we know it from your testing that moving [0] to [5] fixes the crash.
The question is, can we move it to [4], [3], [2] or even [1] instead, without
breaking the system?
I still don't see where the breakage comes from, but this would help us narrow
it
down.
Thanks,
Ingo
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