Re: [PATCH 1/1] x86 TSC: set X86_FEATURE_TSC_RELIABLE, per CPUID

From: Thomas Gleixner
Date: Tue Jun 09 2015 - 04:16:00 EST


On Mon, 8 Jun 2015, Andy Lutomirski wrote:
> On Wed, Jun 3, 2015 at 12:03 PM, Len Brown <lenb@xxxxxxxxxx> wrote:
> > If you boot this machine with "tsc=reliable", to disable the cpu_up
> > check_tsc_sync,
> > what happens? Does the run-time clocksource code detect the bogus TSC values?
> > If yes, how long does that take?
>
> They didn't detect it in the time I watched it.

Which is not surprising as the run-time check is disabled with the
reliable flag as well.

if (tsc_clocksource_reliable)
clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;

Thanks,

tglx
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