From: Ingo Molnar <mingo@elte.hu>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
john stultz <johnstul@us.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Adrian Bunk <bunk@stusta.de>
Subject: Re: [PATCH] i386: Prevent early access to TSC to avoid crash on TSCless systems
Date: Sat, 24 Mar 2007 23:09:45 +0100 [thread overview]
Message-ID: <20070324220945.GA26168@elte.hu> (raw)
In-Reply-To: <1174773769.10840.450.camel@localhost.localdomain>
* Thomas Gleixner <tglx@linutronix.de> wrote:
> commit f9690982b8c2f9a2c65acdc113e758ec356676a3 removed the check for
> cpu_khz from sched_clock(), which prevented early access to the TSC by
> non obvious magic.
>
> This is harmless as long as the CPU has a TSC. On TSCless systems this
> results in an illegal instruction trap.
>
> Replace tsc_disabled and tsc_unstable by tsc_enabled, which is only
> set when the tsc is available and not unstable.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
oops, indeed! I think this should also resolve one of the bugs (TSC-less
Cyrix?) that were reported against -mm some time ago.
Acked-by: Ingo Molnar <mingo@elte.hu>
Ingo
next prev parent reply other threads:[~2007-03-24 22:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-24 22:02 [PATCH] i386: Prevent early access to TSC to avoid crash on TSCless systems Thomas Gleixner
2007-03-24 22:09 ` Ingo Molnar [this message]
2007-03-24 22:30 ` Guillaume Chazarain
2007-03-24 22:32 ` Ingo Molnar
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