Re: [Qemu-devel] [PATCH] virtio: fix HW_COMPAT_2_6 macro for virtio-*-pci drivers

[Greg Kurz <groug@kaod.org>]

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On Tue, 6 Dec 2016 20:30:52 +0000
Stefan Hajnoczi <stefanha@gmail.com> wrote:

> On Tue, Dec 06, 2016 at 05:48:00PM -0200, Eduardo Habkost wrote:
> > On Tue, Dec 06, 2016 at 09:44:11PM +0200, Michael S. Tsirkin wrote:  
> > > On Tue, Dec 06, 2016 at 05:40:29PM -0200, Eduardo Habkost wrote:  
> > > > On Tue, Dec 06, 2016 at 09:36:07PM +0200, Michael S. Tsirkin wrote:  
> > > > > On Tue, Dec 06, 2016 at 05:33:49PM -0200, Eduardo Habkost wrote:  
> > > > > > On Tue, Dec 06, 2016 at 09:31:43PM +0200, Michael S. Tsirkin wrote:  
> > > > > > > On Tue, Dec 06, 2016 at 06:50:47PM +0100, Greg Kurz wrote:  
> > > > > > > > Since commit "9a4c0e220d8a hw/virtio-pci: fix virtio behaviour", passing
> > > > > > > > -device virtio-blk-pci.disable-modern=off has no effect on 2.6 machine
> > > > > > > > types because the internal virtio-pci.disable-modern=on compat property
> > > > > > > > always prevail.
> > > > > > > > 
> > > > > > > > This should ideally be fixed in the qdev properties core code, but it is
> > > > > > > > too late in the QEMU 2.8 schedule. So this patch fixes the issue by setting
> > > > > > > > the compat properties for every virtio-*-pci subtypes instead of the base
> > > > > > > > virtio-pci type.
> > > > > > > > 
> > > > > > > > Signed-off-by: Greg Kurz <groug@kaod.org>  
> > > > > > > 
> > > > > > > What's the rush? Either the issue is or isn't 2.8 material. If it is,
> > > > > > > let's fix it in qdev core now. If it isn't no need for quick fixes,
> > > > > > > just wait a bit and merge qdev core fix after 2.8 is out.  
> > > > > > 
> > > > > > Because it is a regression,  
> > > > > 
> > > > > Regression in 2.7 though, isn't it?  
> > > > 
> > > > Yes. Does that mean we don't mind leaving a regression unfixed in
> > > > 2.8 because it was introduced in 2.7?  
> > > 
> > > Not necessarily, it's a judgement call.  But there will always be
> > > another release.  I would say don't rush it.  
> > 
> > My judgement is that it won't hurt to include the HW_COMPAT_* fix
> > for virtio-pci (this patch, after including the missing classes I
> > pointed out), because it is simple and obvious.
> > 
> > But I agree that this means we don't need the more complex hack I
> > just sent as RFC.  
> 
> This has missed QEMU 2.8.0-rc3 (the deadline was 19:00 UTC December
> 6th).
> 
> This doesn't seem like a release blocker anyway since it's not a 2.8
> regression, it can be fixed in a -stable release.
> 
> Stefan

Sure. There were suggestions to handle the issue in an appropriate
manner. Fixes can be applied downstream if needed.

Thanks everyone!

--
Greg

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