Re: Linux 2.6.39-rc3

From: Joerg Roedel
Date: Fri Apr 15 2011 - 09:11:57 EST

On Wed, Apr 13, 2011 at 07:33:40PM -0700, Linus Torvalds wrote:
> we definitely want to also understand the reason for things not
> working, even if we do revert..

Okay, here it is.

After experimenting with different configurations for the north-bridge
it turned out that a GART related MCE fires at the time the machine
reboots. BIOSes configure the machine to sync-flood in that case which
causes a reboot.

After decoding the MCE it turned out to be a GART TBL Wlk Error. Such
errors can happen if devices (speculativly) access GART ranges mapped
invalid. The AMD BKDG for Fam10h CPUs recommends to disable these errors
at all. But unfortunatly some BIOSes (including the one on my laptop)
forget to do this.

Below is a patch which disables these errors if the BIOS didn't do it.
It fixes the problem on my site.

Alexandre, can you try this patch on your machine too, please?