On Sat, 2015-06-27 at 18:02 -0300, Henrique de Moraes Holschuh wrote:
> On Sat, 27 Jun 2015, Mike Galbraith wrote:
> > > > BIOS setting "Limit CPUID Maximum" upsets new fpu code mightily.
> >
> > That BIOS setting is annotated with the helpful text "Disabled for
> > Windows XP". It makes box say interesting things during boot, like...
> >
> > x86/fpu: XSTATE_CPUID missing!
> >
> >
> > ..or with HEAD, it triggers warning..
> >
> > if (boot_cpu_data.cpuid_level < XSTATE_CPUID) {
> > WARN_ON_FPU(1);
> > return;
> > }
> >
> > ..and all kinds of bad juju follows. I have no idea what the thing does
> > beyond what I can interpolate from the word 'limit'.
>
> Well, it is supposed to disable CPUID levels >= 0x04. This thing should
> *NEVER* be enabled, the last operating system that required it to be enabled
> was Windows 98.
>
> Can/do we override that crap during cpu init? If we cannot/don't, maybe
> instead of limping along with CPUID crippled, it would be better to either
> output a very nasty warning, or outright stop booting [with an appropriate
> error message] ?
Why get all upset? We didn't even notice before, nor did/does that
other OS. A casual "BTW, your BIOS sucks.." should suffice, no?
-Mike
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