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Message-ID: <1326233448.23910.74.camel@pasglop>
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Wed, 11 Jan 2012 09:10:48 +1100
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Subject: Re: [Qemu-devel] [PATCH] virtio-pci: Fix endianness of virtio config
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To: Alexander Graf <agraf@suse.de>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>, David Gibson <dwg@au1.ibm.com>, Andreas =?ISO-8859-1?Q?F=E4rber?= <afaerber@suse.de>, kvm-ppc@vger.kernel.org, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>

On Wed, 2012-01-11 at 09:04 +1100, Benjamin Herrenschmidt wrote:
> On Tue, 2012-01-10 at 22:45 +0100, Alexander Graf wrote:
> > Here's the thing that I don't understand. What exactly is breaking for
> > you? I tried -M pseries on a ppc box and on an x86 box and both times
> > was able to see /dev/vda.
> 
> And mount it and use it ? Here I get the capacity wrong if I don't have
> my patch and can't actually boot a distro off it.

Hrm actually, it might well work with Linux regardless because Linux
only ever does 8 bit accesses to the virtio config space.

It's SLOF that breaks because SLOF uses 2 and 4 byte accesses (which are
allowed per spec as far as I can tell) but the spurrious swapping
happening in that case means we lost the byte address invariance.

Cheers,
Ben.