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Date: Wed, 18 Jun 2014 16:42:04 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v8 00/20] virtio endian-ambivalent target
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Kevin Wolf <kwolf@redhat.com>, Anthony Liguori <aliguori@amazon.com>, Juan Quintela <quintela@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>, Rusty Russell <rusty@rustcorp.com.au>, Alexander Graf <agraf@suse.de>, QEMU Developers <qemu-devel@nongnu.org>, "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>, Stefan Hajnoczi <stefanha@redhat.com>, Amit Shah <amit.shah@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Andreas =?iso-8859-1?Q?F=E4rber?= <afaerber@suse.de>, Greg Kurz <gkurz@linux.vnet.ibm.com>

On Wed, Jun 18, 2014 at 01:53:15PM +0100, Peter Maydell wrote:
> On 18 June 2014 11:38, Stefan Hajnoczi <stefanha@gmail.com> wrote:
> > What bothers me is that real hardware can't do this.
> 
> Real hardware doesn't have "endianness matches guest CPU endianness"
> semantics, which is what the virtio spec mandates...

So it was buggy. We never thought anyone would do a cross endian CPU :(.
We are fixing it in 1.0.

> > Given that VIRTIO
> > 1.0 is always little-endian I guess this is just a temporary hack for
> > ppc little-endian.  Would be nice to add a comment so it's clear why
> > this approach is being taken instead of a cleaner solution.
> 
> Also for ARM big-endian, and indeed for any CPU with runtime
> configurable endianness that wants to use the kernel virtio
> drivers that exist in the real world rather than the theoretical
> future ones that might some day be written for the 1.0 virtio
> spec...
> 
> thanks
> -- PMM

That's not a theoretical future.
Spec will almost certainly be frozen two weeks from now.
So it is almost certain that drivers will be there in 3.17. 

Existing distros can then simply backport the
drivers - same as they would with any other new hardware.

-- 
MST