On Sat, 2007-05-05 at 01:18 +0200, Andi Kleen wrote:-On Friday 04 May 2007 23:29:04 john stultz wrote:One of the 2.6.21 regressions was Guilherme's problem seeing his boxBefore going to hard to maintain DMI black lists we should first check if it's a more general problem and can't it be solved better? Most likely
lock up when the system detected an unstable TSC and dropped back to
using the HPET.
In digging deeper, we found the HPET is not actually incrementing on
this system. And in fact, the reason why this issue just cropped up was
because of Thomas's clocksource watchdog code was comparing the TSC to
the HPET (which wasn't moving) and thought the TSC was broken.
Anyway, Guliherme checked for a BIOS update and did not find one, so
I've added a DMI blacklist against his system so the HPET is not used.
Many thanks to Guilherme for the slow and laborious testing that finally
narrowed down this issue.
that system isn't the one with this issue and I don't want to apply
DMI patches forever.
We can give it a whirl, I just didn't want to add yet another "compare
with some other counter that may or may not work" check. In this case,
probably reading three times in a row and getting the same result would
be a clearly broken box.
In particular: what lspci chipset does it have? If it's Intel it might be
worth checking the datasheet if there is some "HPET stop" bit -- perhaps it could be fixed up.
Guilherme: Could you provide lspci output?
We seem to have a couple of Intel systems recently with HPET trouble.
Ok, I wasn't aware it was a common issue.
thanks
-john