On 06/28/2015 11:40 PM, Ingo Molnar wrote:
>
> 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.
>
It should be moved to [4] or [5]. I would argue that the line setting
X86_FEATURE_ALWAYS should moved up and then fpu__init_system(c) should
be moved after the c_bsp_init() line.
-hpa
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