From: Borislav Petkov <bp@alien8.de>
To: Ronan Pigott <ronan@rjp.ie>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: UMIP and clearcpuid=
Date: Wed, 10 Jun 2026 13:00:54 -0700 [thread overview]
Message-ID: <20260610200054.GDainCdpF585khK77w@fat_crate.local> (raw)
In-Reply-To: <e60f6e46b74131ebaf54793be00618cf13727ede@rjp.ie>
On Wed, Jun 10, 2026 at 07:46:11PM +0000, Ronan Pigott wrote:
> In [1] the clearcpuid= flag was hidden, but afaik this remains the only way to
> disable UMIP.
The reason for wanting to disable it being?
> At the time UMIP was enabled, clearcpuid was apparently determined to be the
> appropriate method of disablement in [2],
Don't confuse "appropriate" with "might be good enough" ;)
> and it remains recommended by the documentation in [3].
That doc says:
"DO NOT USE this cmdline option in production - it is meant to be used only as
a quick’n’dirty debugging aid to rule out a feature-enabling code is the
culprit. If you use it, it’ll taint the kernel."
> If clearcpuid is no good, can we have a sanctioned method to disable UMIP
> protections instead then?
Let's figure out the use case first pls.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2026-06-10 20:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-10 19:46 UMIP and clearcpuid= Ronan Pigott
2026-06-10 20:00 ` Borislav Petkov [this message]
2026-06-10 20:41 ` Ronan Pigott
2026-06-10 23:55 ` Borislav Petkov
2026-06-11 7:53 ` Peter Zijlstra
2026-06-11 16:09 ` Borislav Petkov
2026-06-11 18:37 ` Peter Zijlstra
2026-06-12 2:21 ` Borislav Petkov
2026-06-12 6:42 ` Peter Zijlstra
2026-06-12 14:49 ` Borislav Petkov
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