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RE: [Xen-devel] Xen-3.2.1 VT-d Support (NOT SURE WHETHER IT'S A BUG OR..

To: dexuan.cui@xxxxxxxxx
Subject: RE: [Xen-devel] Xen-3.2.1 VT-d Support (NOT SURE WHETHER IT'S A BUG OR...)
From: "Bryan York" <bryan.york@xxxxxxxxx>
Date: Tue, 5 Aug 2008 15:17:11 -0700
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
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I'm also seeing this exact same problem. I've posted on xen-users, but did not get an answer. Venkat seems to be experiencing the same problem as me. I have the latest BIOS for my motherboard DQ35JO. (BIOS ver 933) I'm running a Q6600 as well. It hangs at "Brought up 4 CPUs." I've tried all sorts of combinations of Xen versions and kernels to get this working. And, yes, VT and VT-d are enabled in my BIOS.

1) CentOS 5.2 SRPMS compiled with Xen 3.2.1. Adding pci=nommconf does not get it to boot.

2) Mercurial Xen-3.2-testing. Here, after adding pci=nommconf, I get:

(XEN) [VT-D]dmar.c:441: RMRR is incorrect.
(XEN) Failed to parse ACPI DMAR.  Disabling VT-d.
(XEN) [VT-D]ACPI DMAR:No DMAR devices found

3) Mercurial Xen-unstable, I get "I/O Virtualisation disabled" I can't find any reason why this is the case. VT-D is not enabled.

I would really like to find the cause for this. I don't know if this is a BIOS bug or what. This board is supposedly supported on Xen per the VT-D wiki. Other people seem to have the same problem as me:


Thanks for any and all help,


The BIOS version I use may be not the exact one as yours. I mean I expect you're
not using a very old BIOS. :-)

How about trying the xen 3.2.2-rc2 and the latest xen-unstable first? There are some VT-d bug fixes between 3.2.1 (you're using it) and 3.2.2-rc2.


-- Dexuan


From: Kumar, Venkat [mailto:Venkat.Kumar@xxxxxxx] Sent: 2008年8月5日 14:37 To: Cui, Dexuan; xen-devel@xxxxxxxxxxxxxxxxxxx Subject: RE: [Xen-devel] Xen-3.2.1 VT-d Support (NOT SURE WHETHER IT'S A BUG

If you don't mind can you send me the BIOS version you are using?




Venkata Kumar Duvvuru,

LSI Engenio,

Adv. Development,


Mob: +91-9880318542

Off : +91-80-41978700 ( Extn : 3544 )


From: Cui, Dexuan [mailto:dexuan.cui@xxxxxxxxx] Sent: Tuesday, August 05, 2008 12:03 PM To: Kumar, Venkat; xen-devel@xxxxxxxxxxxxxxxxxxx Subject: RE: [Xen-devel] Xen-3.2.1 VT-d Support (NOT SURE WHETHER IT'S A BUG

Hi Venkat,

Can you confirm you're using the latest BIOS? Can you try the xen 3.2.2-rc2 and
the latest xen-unstable on the same host?

I have the similar host. Xen 3.2.2-rc2 and the latest xen-unstable both work
well on it.


-- Dexuan


From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Kumar, Venkat Sent: 2008年8月5日 12:21 To: xen-devel@xxxxxxxxxxxxxxxxxxx Subject: [Xen-devel] Xen-3.2.1 VT-d Support (NOT SURE WHETHER IT'S A BUG OR...)

After building Xen-3.2.1 I could successfully boot into it if I avoid giving
vtd=1 as the boot parameter.

If I pass vtd=1 as the boot parameter to xen, the system hangs while booting.

The system hangs after the following messages


Boot messages


[Xen] Brought up 2 CPUs...


My chipset DQ35 series is having VT-d support and is enabled in the BIOS as

My domain0 is CentOS-5.2(

Is this a possible bug or some thing else??

Any Idea??


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