Re: [PATCH 1/3] x86, intel: Output microcode revision

From: Andi Kleen
Date: Wed May 25 2011 - 12:58:50 EST


> > This can happen if for example the BIOS somehow does not apply the right
> > microcode to all CPUs. It can also happen if physically different microcode
> > version CPUs are mixed. In theory people can mix steppings as well.
>
> In PRACTICE people WILL mix steppings as well.

Yes exactly. I used to have a system with one P3 supporting FXSAVE
and other not :-) I had to fix the kernel back then to support this.
The system worked perfectly fine after the kernel was fixed.

So the check proposed is a bad idea. It would trigger
on real boxes which don't have any obvious problems.

-Andi
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