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Date: Thu, 07 Mar 2013 15:48:05 +0100
From: Hannes Reinecke <hare@suse.de>
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Subject: [Qemu-devel] Windows doesn't like MSI/MSI-X
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To: "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>
Cc: Alexander Graf <agraf@suse.de>, "Michael S. Tsirkin" <mst@redhat.com>

Hi all,

recently I've tried to teach megasas MSI/MSI-X. While it works=20
perfectly under Linux, Windows refuses to.

With really strange symptoms:
Windows Vista will BSOD when both MSI/MSI-X registers are present,=20
and Windows 7 will hang as Windows (apparently) thinks MSI/MSI-X is=20
enabled, whereas qemu doesn't and uses INTx.
So the Windows 7 guest will never see any interrupts.

The _really_ odd thing is that when I remove the MSI-X capability=20
Windows will fall back to INTx and everything works.

Even more curious is that from the logs Windows will only ever write=20
zeros into the MSI/MSI-X config registers.
Which makes me wonder what's going on there.

As I'm not sure if that's my fault I was wondering if anybody every=20
succeeded in getting AHCI to use MSI under Windows.
Any pointers?

Cheers,

Hannes
--=20
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg
GF: J. Hawn, J. Guild, F. Imend=F6rffer, HRB 16746 (AG N=FCrnberg)