Re: [Qemu-devel] [PATCH] compat: Use explicit type names on HW_COMPAT_2_6

[Eduardo Habkost]

On Mon, Jan 07, 2019 at 09:12:06AM +0100, Cornelia Huck wrote:
> On Fri, 4 Jan 2019 20:00:50 -0200
> Eduardo Habkost <address@hidden> wrote:
> 
> > On Fri, Jan 04, 2019 at 04:13:15PM -0500, Michael S. Tsirkin wrote:
> > > On Fri, Jan 04, 2019 at 07:06:56PM -0200, Eduardo Habkost wrote:  
> > > > On Fri, Jan 04, 2019 at 03:48:02PM -0500, Michael S. Tsirkin wrote:  
> > > > > On Fri, Jan 04, 2019 at 06:09:52PM -0200, Eduardo Habkost wrote:  
> 
> > > > > > Anyway, while writing this I noticed another issue: many of the
> > > > > > virtio devices in QEMU 2.6 were already modern-only!
> > > > > > 
> > > > > > Setting disable-modern=off on modern-only devices like virtio-vga
> > > > > > or virtio-tablet-pci doesn't make sense.  This means setting
> > > > > > virtio-pci.disable-modern=off on HW_COMPAT_2_6 was incorrect even
> > > > > > before the -non-transitional and -transitional device types were
> > > > > > introduced.  
> > > > > 
> > > > > 
> > > > > It did create an opportunity to create non working devices.
> > > > > 
> > > > > Whether that's incorrect as such I'm not sure.  
> > > > 
> > > > This is not just creating the opportunity for an user to
> > > > disable-modern=on.  HW_COMPAT_2_6 is actually setting
> > > > disable-modern=on on virtio-vga and other modern-only devices.
> > > > Sounds like a mistake to me.
> > > > 
> > > > Luckily those modern-only devices silently ignore the
> > > > disable-modern/disable-legacy properties, but this might change
> > > > in the future.  
> > > 
> > > Worry about it then?  
> > 
> > Right, we don't need to worry about it today.  But if a solution
> > to the crash reported by Thomas will make the problem go away,
> > that's even better.
> 
> It seems your patch with the modern-only devices removed from the list
> would achieve that?

I think so.  But I think I'll do the removal of modern-only
devices from the list in a separate patch, just to be safe.

-- 
Eduardo