RE: [Xen-devel] Xen 4.0 + PVOPS + Intel VTD + USB EHCI = BUG()

["Han, Weidong" <weidong.han@xxxxxxxxx>]

Hi Dave,

I found the DMAR (VT-d) was also enabled in pvops dom0 in the log. It should 
not happen because Xen zaps ACPI DMAR signature to prevent dom0 using VT-d. 
Could you apply below small patch to confirm that xen really zaps ACPI DMAR?

diff -r 2f98b700605f xen/drivers/passthrough/vtd/dmar.c
--- a/xen/drivers/passthrough/vtd/dmar.c    Wed Jan 27 08:59:47 2010 +0000
+++ b/xen/drivers/passthrough/vtd/dmar.c    Thu Jan 28 09:44:31 2010 +0800
@@ -673,6 +673,8 @@ out:
 out:
     /* Zap ACPI DMAR signature to prevent dom0 using vt-d HW. */
     dmar->header.signature[0] = '\0';
+    printk(XENLOG_WARNING
+           "Zap ACPI DMAR signature to prevent dom0 using VT-d HW.\n");
     return ret;
 }


-----Original Message-----
From: David P. Quigley [mailto:dpquigl@xxxxxxxxxxxxx] 
Sent: Thursday, January 28, 2010 2:48 AM
To: Han, Weidong
Cc: Pasi KÃrkkÃinen; Daniel Stodden; xen-devel@xxxxxxxxxxxxxxxxxxx; Konrad 
Rzeszutek Wilk
Subject: RE: [Xen-devel] Xen 4.0 + PVOPS + Intel VTD + USB EHCI = BUG()

On Wed, 2010-01-27 at 10:49 +0800, Han, Weidong wrote:
> Can you pls post the serial output? It should have warning messages if it is 
> caused by VT-d.
> 
> Regards,
> Weidong
> 
> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of David P. 
> Quigley
> Sent: Wednesday, January 27, 2010 4:21 AM
> To: Pasi KÃrkkÃinen
> Cc: Daniel Stodden; xen-devel@xxxxxxxxxxxxxxxxxxx; Konrad Rzeszutek 
> Wilk
> Subject: Re: [Xen-devel] Xen 4.0 + PVOPS + Intel VTD + USB EHCI = 
> BUG()
> 
> On Tue, 2010-01-26 at 21:46 +0200, Pasi KÃrkkÃinen wrote:
> > On Tue, Jan 26, 2010 at 02:30:09PM -0500, David P. Quigley wrote:
> > > I have a small update on the problem. It does seem like it is tied 
> > > to VT-D because I just turned it off in the bios and the dom0 
> > > manages to boot on top of xen and I can log in. Are there any 
> > > options for VT-D that you would like me to try to help pin point the 
> > > problem?
> > > 
> > 
> > At least update to the latest xen-unstable tree, since -rc2 got just 
> > released, and it has some VT-d fixes/changes.
> > 
> > -- Pasi
> 
> I updated my xen-unstable tree and tried to turn VT-D back on and it 
> breaks booting again so we still have a bug on our hands.
> 
> Dave
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel

Hello,
        Attached is the full serial console output with vt-d enabled from the 
xen 4.0-pre ascii art to the kernel oops in dom0.

Dave

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