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Re: [Qemu-devel] [PATCH] add pci-bridge-seat
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] [PATCH] add pci-bridge-seat |
Date: |
Tue, 17 Mar 2015 08:16:45 +0100 |
On Mo, 2015-03-16 at 13:20 +0100, Michael S. Tsirkin wrote:
> On Mon, Mar 16, 2015 at 11:36:43AM +0100, Gerd Hoffmann wrote:
> > Simplifies multiseat configuration, see
> > docs/multiseat.txt update for details.
> >
> > Signed-off-by: Gerd Hoffmann <address@hidden>
> > ---
> > docs/multiseat.txt | 19 +++++++++++++++++++
> > docs/specs/pci-ids.txt | 1 +
> > hw/pci-bridge/pci_bridge_dev.c | 25 ++++++++++++++++++++++++-
> > include/hw/pci/pci.h | 1 +
> > 4 files changed, 45 insertions(+), 1 deletion(-)
> >
> > diff --git a/docs/multiseat.txt b/docs/multiseat.txt
> > index b963665..814496e 100644
> > --- a/docs/multiseat.txt
> > +++ b/docs/multiseat.txt
> > @@ -106,6 +106,25 @@ the devices attached to the seat.
> > Background info is here:
> > http://www.freedesktop.org/wiki/Software/systemd/multiseat/
> >
> > +
> > +guest side with pci-bridge-seat
> > +-------------------------------
> > +
> > +Qemu version FIXME and newer has a new pci-bridge-seat device which
> > +can be used instead of pci-bridge. Just swap the device name in the
> > +qemu command line above. The only difference between the two devices
> > +is the pci id. We can match the pci id instead of the device path
> > +with a nice generic rule now, which simplifies the guest
> > +configuration:
> > +
> > + address@hidden ~]# cat /etc/udev/rules.d/70-qemu-pci-bridge-seat.rules
> > + SUBSYSTEM=="pci", ATTR{vendor}=="0x1b36", ATTR{device}=="0x000a", \
> > + TAG+="seat", ENV{ID_AUTOSEAT}="1"
> > +
> > +Patch with this rule will be submitted to upstream udev/systemd, so
> > +long-term, when systemd with this lands in distros, things will work
> > +just fine without any manual guest configuration.
> > +
> > Enjoy!
> >
>
> I'm confused. What's wrong with using the regular bridge,
> and ATTR{vendor}=="0x1b36", ATTR{device}=="0x0001"?
It works just fine, thats why the new device is identical except for the
id.
The whole point is to simplify guest-side configuration, by passing one
bit of extra information to the guest: Whenever the pci bridge with the
devices below it should be considered a new seat (-device
pci-bridge-seat) or not (-device pci-bridge).
cheers,
Gerd