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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Thu, 05 Nov 2015 15:42:09 +0100
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Subject: Re: [Qemu-devel] virtio-gpu doesn't build if you do a linux-headers
 update from kvm/next
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>, QEMU Developers <qemu-devel@nongnu.org>

On Do, 2015-11-05 at 12:32 +0000, Peter Maydell wrote:
> On 5 November 2015 at 12:13, Gerd Hoffmann <kraxel@redhat.com> wrote:
> >> etc, because all the virtio_gpu definitions disappear from
> >> include/standard-headers/linux/virtio_gpu.h.
> >
> > Updates not yet in mainline, they are sitting in drm-next and should
> > land during the merge window (i.e. 4.4-rc1 should have them).
> >
> > I'd suggest to exclude virtio_gpu.h changes when updating linux headers
> > for the time being.
> 
> I would strongly prefer it if we could get to a point where
> we can say "kernel headers must only be updated from this tree"
> and be guaranteed that it always works. This used to be true
> with the tree in question being kvm/next, but it doesn't seem
> to be so now. If it's going to be common that we have header
> changes that don't go via kvm/next, maybe we need to coordinate
> a tree that merges together the abi-guaranteed-stable changes
> from different places before they hit mainline?

Chicken & egg issue in that case because airlied (linux kernel drm
maintainer) asked to have the qemu changes merged before taking the
virtio-gpu pull request.  So I had no other chance than creating the
patches with not-yet upstream virtio header changes ...

cheers,
  Gerd