[PATCH 0/1] UBUNTU: SAUCE: x86: mtrr: don't modify RdDram/WrDram bits of fixed MTRRs

[TJ]

LP #292619 https://launchpad.net/bugs/292619

This is a cherry-pick from x86-tip that should land for mainline
2.6.29.1. It resolves kernel panics during boot for SMP AMD CPU systems.

The cause is the MTRRs for the boot CPU (BP) and additional CPUs (AP)
being modified by Linux for fixed MTRRs - in part because BIOS doesn't
clear SYSCFG[MtrrFixDramModEn].

The affected systems boot only using acpi=ht, acpi=off or when the
kernel is built with CONFIG_MTRR=n.

I've cherry-picked the x86-tip commit 3ff42da5048649 from

git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip.git

It applies cleanly to Jaunty.

LP #292619 reports this issue since 2.6.24-19-server so if the Jaunty
patch solves the user's issue this patch would be a candidate for Hardy
and Intrepid SRUs.