Re: [RFC PATCH] Use feature bit names in clearcpuid=
From: Borislav Petkov
Date: Tue Sep 22 2020 - 04:13:24 EST
On Tue, Sep 22, 2020 at 10:03:03AM +0200, Thomas Gleixner wrote:
> On Sun, Sep 20 2020 at 17:42, Borislav Petkov wrote:
> > Hi,
> > so tglx hates this clearcpuid= interface where you have to give the
> > X86_FEATURE array indices in order to disable a feature bit for testing.
> > Below is a first attempt (lightly tested in a VM only) to accept the bit
> > names from /proc/cpuinfo too.
> > I say "too" because not all feature bits have names and we would still
> > have to support the numbers. Yeah, yuck.
> > An exemplary cmdline would then be something like:
> > clearcpuid=de,440,smca,succory,bmi1,3dnow ("succory" is wrong on
> > purpose).
> > and it says:
> > [ 0.000000] Clearing CPUID bits: de 13:24 smca bmi1 3dnow
> > Also, I'm thinking we should taint the kernel when this option is used.
> > Thoughts?
> Yes, instead of making it differently horrible, can we finally remove that
> nonsense which should have never been there in the first place?
Fine with me - I don't need it.
I believe dhansen has a use-case or two, CCed.