[systemd-devel] [PATCH] loginctl: add rule for qemu's pci-bridge-seat

[Gerd Hoffmann]

On Mi, 2015-07-01 at 13:10 +0200, David Herrmann wrote:
> Hi
> 
> On Mon, Jun 29, 2015 at 9:42 AM, Gerd Hoffmann <kraxel at redhat.com> wrote:
> > Signed-off-by: Gerd Hoffmann <kraxel at redhat.com>
> > ---
> >  src/login/71-seat.rules.in | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/src/login/71-seat.rules.in b/src/login/71-seat.rules.in
> > index ab7b66f..270da71 100644
> > --- a/src/login/71-seat.rules.in
> > +++ b/src/login/71-seat.rules.in
> > @@ -17,6 +17,12 @@ SUBSYSTEM=="usb", ATTR{bDeviceClass}=="09", TAG+="seat"
> >  # 'Plugable' USB hub, sound, network, graphics adapter
> >  SUBSYSTEM=="usb", ATTR{idVendor}=="2230", ATTR{idProduct}=="000[13]", ENV{ID_AUTOSEAT}="1"
> >
> > +# qemu (version 2.4+) has a PCI-PCI bridge (-device pci-bridge-seat)
> > +# to group devices belonging to one seat.
> > +# see http://git.qemu.org/?p=qemu.git;a=blob;f=docs/multiseat.txt
> > +SUBSYSTEM=="pci", ATTR{vendor}=="0x1b36", ATTR{device}=="0x000a", \
> > +       TAG+="seat", ENV{ID_AUTOSEAT}="1"
> > +
> 
> I have no idea why this is correct. Could you provide a proper commit-message?
> 
> Is this specific VID/PID match exclusively used for seat'ing?

Yes.  The normal pci-pci bridge ("-device pci-bridge") has 1b36:0001.
The new pci-bridge-seat was specifically added to simplify guest-side
multiseat configuration.  It is identical to the normal pci-pci bridge,
except that it has a different id (1b36:000a) so we can match it and
configure multiseating automatically.

The documentation linked in the comment has all the details.  /me
through this would be more useful as it is visible on the installed
system (unlike the git commit message).

But I can cut & paste the paragraph above into the commit message and
resend.  Or should I redo the github pull-request instead?

cheers,
  Gerd