From: Borislav Petkov <bp@alien8.de>
To: Thomas Gleixner <tglx@linutronix.de>,
Dave Hansen <dave.hansen@intel.com>
Cc: x86-ml <x86@kernel.org>, lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] Use feature bit names in clearcpuid=
Date: Tue, 22 Sep 2020 10:13:12 +0200 [thread overview]
Message-ID: <20200922081312.GA22660@zn.tnic> (raw)
In-Reply-To: <87mu1ib5mw.fsf@nanos.tec.linutronix.de>
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.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
prev parent reply other threads:[~2020-09-22 8:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-20 15:42 [RFC PATCH] Use feature bit names in clearcpuid= Borislav Petkov
2020-09-20 16:16 ` Arvind Sankar
2020-09-20 17:29 ` Borislav Petkov
2020-09-20 18:35 ` Arvind Sankar
2020-09-20 18:59 ` Borislav Petkov
2020-09-22 8:03 ` Thomas Gleixner
2020-09-22 8:13 ` Borislav Petkov [this message]
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