8.1-RC2 MCE caused by some LAPIC/clock changes? (was: 8.1-RC2 - PCI fatal error or MCE triggered by USB/ehci on Sun X4100M2?)

[John Baldwin]

On Saturday, July 17, 2010 2:35:21 pm Markus Gebert wrote:
> 
> On 13.07.2010, at 16:02, Markus Gebert wrote:
> 
> > Unfortunately, I have not been able to get anything useful out the svn 
commit logs, which could explain this. Maybe someone else has an idea what 
could have changed between 7 and 8 to break it, and again between 8 and 
CURRENT to magically fix it again.
> 
> I tracked this down further. I couldn't easily downgrade my 8.1 installation 
to see when the problem was introduced because the zpool version used is 14. 
So I tried to figure out, when the problem was solved in CURRENT.
> 
> I started with the first possible revision that can boot off my v14 pool 
(r201143, Dec 28, zfs v14 commit). With this revision, I was able to trigger 
the MCE.
> 
> Then I took some later revision (rev206010, Apr 1, chosen randomly), and I 
couldn't reproduce the problem. I started narrowing the revisions down until I 
found out, that while on r202386 I'm still able to trigger the MCE, r202387 
seems to solve the problem on CURRENT:
> 
> http://svn.freebsd.org/viewvc/base?view=revision&revision=202387

Although this change was MFC'd, it was later disabled by default because it 
causes issues on other machines.  I think there is a tunable you need to set 
in loader.conf to enable it for 8.1.  Attilio (the author of that commit) 
should know which tunable to set.

-- 
John Baldwin