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Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 f
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD |
Date: |
Mon, 19 May 2014 13:13:21 +0300 |
On Mon, May 19, 2014 at 09:25:19AM +0000, Chen, Tiejun wrote:
> > -----Original Message-----
> > From: Gerd Hoffmann [mailto:address@hidden
> > Sent: Monday, May 19, 2014 2:45 PM
> > To: Chen, Tiejun
> > Cc: address@hidden; address@hidden;
> > address@hidden; address@hidden; address@hidden;
> > address@hidden; address@hidden; Kay, Allen M;
> > address@hidden; address@hidden;
> > address@hidden; Zhang, Yang Z
> > Subject: Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve
> > 00:02.0 for INTEL IGD
> >
> > Hi,
> >
> > > + /*
> > > + * Some video bioses and gfx drivers will assume the bdf of IGD is
> > 00:02.0.
> > > + * So user need to set it to 00:02.0 in Xen configure file
> > > explicitly,
> > > + * otherwise IGD will fail to work.
> > > + */
> > > + pci_reserve_pci_devfn(b, PCI_DEVFN(2, 0));
> >
> > That is asking for trouble. Slot 2 is used by the qemu vga cards by
> > default, and
> > for quite a while (before memory api was merged) it even was impossible to
> > change it. libvirt still places the vga card at slot
> > 2 for that reason -> boom. I wouldn't be surprised if you find that
> > assumption
> > in other management libs / apps too.
> >
> > Why do you need that patch in the first place? It should be possible to
> > configure qemu to not occupy slot 2 if you need it that way. Just pass
> > '-vga
> > none' to qemu. Which you probably want anyway if you pass-through a vga to
> > the guest. And explicitly configure a slot (via addr=
>
> I think '-vga none' just guarantees the qemu vga cards doesn't occupy
> 00:02.0, but this doesn't mean others use this specific slot since in qemu
> internal, we always pass -1 to assign a slot automatically to register a PCI
> device. So in some cases, we can't get this slot as we expect since that is
> already assigned previously before we need this.
So stop doing this.
Address -1 is a short-cut intended for humans.
In particular we have no way to guarantee that migration works unless
you specify addresses explicitly.
> > property) for all your pci devices. Doing it only for the IGD works too if
> > you list
> > the device before any other pci device on the qemu command line.
>
> So in my test scenario, we can see this information:
>
> PCI: slot 2 function 0 not available for xen-pci-passthrough, in use by
> xen-platform
> Thanks
> Tiejun
I think the best fix is to give priority to devices that supply a
specific slot.
I'll look into this.
--
MST
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 3/8] xen, gfx passthrough: basic graphics passthrough support, (continued)
[Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Tiejun Chen, 2014/05/16
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Konrad Rzeszutek Wilk, 2014/05/16
- Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Gerd Hoffmann, 2014/05/19
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Fabio Fantoni, 2014/05/19
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Zhang, Yang Z, 2014/05/19
- Re: [Qemu-devel] [Xen-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Chen, Tiejun, 2014/05/19
- Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Chen, Tiejun, 2014/05/19
- Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Chen, Tiejun, 2014/05/20
- Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Michael S. Tsirkin, 2014/05/20
Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Gerd Hoffmann, 2014/05/19
Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Chen, Tiejun, 2014/05/19
Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Gerd Hoffmann, 2014/05/19
Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Daniel P. Berrange, 2014/05/19
Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Chen, Tiejun, 2014/05/21
Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Chen, Tiejun, 2014/05/21
Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Gerd Hoffmann, 2014/05/22
Re: [Qemu-devel] [v2][PATCH 4/8] xen, gfx passthrough: reserve 00:02.0 for INTEL IGD, Chen, Tiejun, 2014/05/22