linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Thomas Gleixner <tglx@linutronix.de>
To: Borislav Petkov <bp@alien8.de>, x86-ml <x86@kernel.org>
Cc: lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] Use feature bit names in clearcpuid=
Date: Tue, 22 Sep 2020 10:03:03 +0200	[thread overview]
Message-ID: <87mu1ib5mw.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200920154228.GB7473@zn.tnic>

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?

Thanks,

        tglx

  parent reply	other threads:[~2020-09-22  8:03 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 [this message]
2020-09-22  8:13   ` Borislav Petkov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87mu1ib5mw.fsf@nanos.tec.linutronix.de \
    --to=tglx@linutronix.de \
    --cc=bp@alien8.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).