Strange problem with 8-stable, VMWare vSphere 4 & AMD CPUs (unexpected shutdowns)

[Andriy Gapon]

on 11/02/2010 06:37 Alan Cox said the following:
> Here is what I know.  Several of us, myself included, have been able to
> reproduce either lockups or machine check exceptions when BOTH the machine
> check driver and superpages are enabled on AMD family 10h processors.  There
> have been no reports of this problem on either Intel or earlier AMD
> processors.  Moreover, there is no evidence of instability in AMD family 10h
> processors until the machine check driver is enabled.  By default, FreeBSD
> 8.0 enables superpages but disables the machine check driver.  So, running
> natively, i.e., without virtualization, you shouldn't experience a problem,
> unless you explicitly enable the machine check driver.  However, running on
> top of a hypervisor, like vSphere 4, you might face a problem because the
> hypervisor might enable machine check exceptions, regardless of what the
> FreeBSD guest does.  I really don't know whether vSphere 4 enables machine
> check exception or not.  If it does, then either you disable the use of
> superpages in the FreeBSD guest, or you find a way to disable the machine
> check driver in the hypervisor.

I'd like to mention another possibility, just in case: machine check might be
enabled/done by firmware (e.g. BIOS).  This typically could be the case for
high-end-ish/server systems.

-- 
Andriy Gapon