Re: Current git fails to boot with VT-D enabled due to flood of DMAR errors
From: Robert Hancock
Date: Sun Sep 20 2009 - 00:46:22 EST
On 09/19/2009 10:41 PM, David Woodhouse wrote:
On Sat, 2009-09-19 at 22:32 -0600, Robert Hancock wrote:
On an Asus P7P55D Pro-based system (Lynnfield CPU), with Intel VT-d
enabled in the BIOS, on 2.6.30.5 (the previous version I tested) I get
these lines in dmesg:
DMAR:Host address width 36
DMAR:DRHD (flags: 0x00000001)base: 0x00000000fed90000
DMAR:RMRR base: 0x00000000000e4000 end: 0x00000000000e7fff
DMAR:RMRR base: 0x00000000bf7ec000 end: 0x00000000bf7fffff
Not all IO-APIC's listed under remapping hardware
In current -git, I get these lines as well, but then I get this:
DRHD: handling fault status reg ffffffff
DMAR:[DMA Read] Request device [ff:1f.7] fault addr fffffffffffff000
DMAR:[fault reason 255] Unknown
The last two lines repeat in a continuous flood and the system doesn't
boot. This happens even if I pass "intel_iommu=off" (which seems like
it's already the default).
Could be a kernel bug or a BIOS bug, but in the latter case we should
probably deal with it better. The registers all reading FF seems like
maybe the registers are disabled or something..
This ought to be 'fixed' in linux-next by this commit:
http://git.infradead.org/iommu-2.6.git/commitdiff/0815565ad
Please try linux-next or the iommu tree from
git://git.infradead.org/iommu-2.6.git
Yeah, I just came across that patch. Is that going to get pushed for
2.6.32? It seems like something caused us to start tripping over this by
default when we didn't before. (Passing intel_iommu=on with 2.6.30.5
does cause the same problem.)
I'll try and report the problem to Asus, obviously something's borked
with VT-d in their BIOS currently..
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