Re: [Qemu-devel] [PATCH RFC] hw/virtio: Add PCIe capability to virtio devices

[Michael S. Tsirkin]

On Tue, Oct 13, 2015 at 10:13:37AM +0200, Gerd Hoffmann wrote:
> On Mo, 2015-10-12 at 18:42 +0300, Michael S. Tsirkin wrote:
> > On Mon, Oct 12, 2015 at 06:17:54PM +0300, Marcel Apfelbaum wrote:
> > > The virtio devices are converted to PCI-Express
> > > if they are plugged into a PCI-Express bus and
> > > the 'modern' protocol is enabled.
> > > 
> > > Signed-off-by: Marcel Apfelbaum <address@hidden>
> > > ---
> > > 
> > > This is an RFC because all it does it adds the PCIe capability and 
> > > nothing more.
> > 
> > Express capability is easy.
> > But if you go over express space you will see that a bunch of
> > other capabilities are required, such as PM capability etc.
> > These might need more work.
> 
> Also what about the legacy io bar?  I guess we'd better avoid that for
> express devices.

This needs some thought.  We definitely still want a way to enable it I
think, e.g. for old guests.

> Maybe it makes sense to add virtio-*-pcie devices (virtio-1.0 only, with
> pcie caps)?
> 
> cheers,
>   Gerd

Personally I think it's ugly enough to remember the need to specify -pci.
OTOH the need to specify upstream and downstream ports is even uglier.
Any idea how to address both issues at the same time?

-- 
MST