linux-kernel - Re: [regression, bisected] fails to boot on Dell Optiplex 760 with VT-d enabled

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Message-ID: <4A89E0D3.7040308@debian.org>
Date:	Tue, 18 Aug 2009 01:59:31 +0300
From:	Faidon Liambotis <paravoid@...ian.org>
To:	David Woodhouse <david.woodhouse@...el.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	"Han, Weidong" <weidong.han@...el.com>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	"Kay, Allen M" <allen.m.kay@...el.com>,
	"Yu, Fenghua" <fenghua.yu@...el.com>
Subject: Re: [regression, bisected] fails to boot on Dell Optiplex 760 with
 VT-d enabled

David Woodhouse wrote:
> On Mon, 2009-08-17 at 14:27 -0700, Faidon Liambotis wrote:
>> I am experiencin a bug on an Dell Optiplex 760 with a configuration that
>> has an Intel Core2 Q9550 CPU and with an up-to-date BIOS, version A03.
>>
>> When "VT for Direct I/O" is enabled in the BIOS, v2.6.30 boots and works
>> perfectly, while v2.6.31-rc1..rc6 fail (both of them x86-64).
>>
>> More specifically, I get an endless loop of printing the following
>> messages in
>> the screen:
>>         DMAR: [DMA Read] Request device [ff:1f.7] fault addr
>>               fffffffffffff000
>>         DMAR: [fault reason 255] Unknown
>> and the boot process doesn't move on from there.
> 
> Is it fixed by http://git.infradead.org/iommu-2.6.git/commit/0815565a ?
Yes it is (v2.6.31-rc6 with 0815565a cherry-picked). Thanks!
Should I expect this to reach v2.6.31?

> I strongly suspect you weren't actually using the IOMMU in your
> 'working' 2.6.30 kernel? Can you show a full log of that one booting?
Could easily be the case, as I said, I haven't tested it (and have
absolutely no idea how to). Full log is attached.
Excerpt for your convienience:
---
DMAR:Host address width 36
DMAR:DRHD (flags: 0x00000000)base: 0x00000000fedc1000
DMAR:DRHD (flags: 0x00000000)base: 0x00000000fedc2000
DMAR:DRHD (flags: 0x00000000)base: 0x00000000fedc3000
DMAR:DRHD (flags: 0x00000001)base: 0x00000000fedc4000
DMAR:RMRR base: 0x00000000cda58000 end: 0x00000000cda6ffff
DMAR:RMRR base: 0x00000000cdc00000 end: 0x00000000cfffffff
Not all IO-APIC's listed under remapping hardware
---

If it's a BIOS issue, any ideas on who to contact at Dell for this?

Thanks,
Faidon

View attachment "2.6.30-dmesg" of type "text/plain" (48845 bytes)