Re: x86_32 tsc/pit and hrtimers

From: Pavel Machek
Date: Thu Oct 09 2008 - 13:20:31 EST


Hi!

>> Can you please tell me if this is supposed to work, and I just have a
>> poorly configured kernel; or if TSC/PIT drivers were not designed to work
>> this way in the first place. If it wasn't designed to do this, do you
>> have any tips on implementing this, since I'll be needing to do that?
>>
> This is not supposed to work, but it might be worthwhile to add a boot
> option to force the kernel to trust the TSC, as hardware that lacks any
> high-res timers also tends to be primitive enough that the TSC can be
> trusted, if it exists. If you patch out the CLOCK_SOURCE_MUST_VERIFY
> flag on the TSC, do you get correctly-functioning high-res timers on this
> system?

Untrue. Unstable tsc dates back to pentium MMX times.

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/