Re: [Xen-devel] GPU passthrough issue when VM is configured with 4G memory

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Tue, Mar 05, 2013 at 03:21:46PM +0100, Matthias wrote:
> I can recreate the issue:
> 
> Whereas xen-unstable does VGA passthrough fine with more then 4G RAM
> with traditional qemu, xen's qemu  upstream does only work with memory
> < 4G.
> 

Does "normal" PCI passthrough work with qemu upstream + xen-unstable and >4G 
RAM?
Say, a NIC, or a USB controller, or a soundcard.

-- Pasi

> 
> 2013/3/5 Pasi Kärkkäinen <pasik@xxxxxx>:
> > On Tue, Mar 05, 2013 at 12:44:36PM +0000, Hanweidong wrote:
> >> >
> >> > >    I have tried to passthrough GPU card(Nvidia quadro 4000) on the 
> >> > > latest
> >> > Xen
> >> > >    unstable version (QEMU is using Qemu-upsteam-unstable, not 
> >> > > traditional
> >> > >    Qemu). This issue as below:
> >> > >
> >> >
> >> > I don't think qemu-upstream has GPU/VGA passthrough support yet.
> >>
> >> Qemu-upstream already supports GPU/VGA pass-through.
> >>
> >
> > Really? With Xen?
> > I haven't seen the patches..
> >
> >> If we configure VM memory with 3G, GPU pass-through works well.
> >>
> >
> > Right..
> >
> >
> >> >
> >> >
> >> > >           Windows7 64-bit guest will blue screen when GPU passthrough
> >> > >    configure 4g memory,blue screen code is 50, and SUSE 11 64-bit guest
> >> > will
> >> > >    always stay at the grub screen.  I noticed that it will relocate 
> >> > > RAM that
> >> > >    overlaps PCI space in pci_setup()(tools/hvmloader/pci.c). If VM 
> >> > > memory
> >> > is
> >> > >    configured with 3G, it won't cause relocate RAM that overlaps PCI 
> >> > > space
> >> > in
> >> > >    pci_setup(), and GPU pass-through is no problem. So it seems this 
> >> > > issue
> >> > is
> >> > >    related to "relocate RAM" in pci_setup().
> >> > >
> >> > >           In the failure case (VM memory is 4G), I used "memtest" to
> >> > check
> >> > >    memory of the VM which configured with more than 4G memory, the last
> >> > 256M
> >> > >    has errors.
> >> > >
> >> > >
> >> > >
> >> > >    BTW, Xen 4.1.2 doesn't have this issue.
> >> > >
> >> >
> >> > I assume with Xen 4.1.2 you're using qemu-traditional.. ?
> >>
> >>  Yes, we tried Xen 4.1.2 with qemu-traditional.
> >>
> >> >
> >> > Try using qemu-traditional also with xen-unstable.
> >> >
> >>
> >> OK, we will have a try. But seems it's not qemu's problem, we can make GPU 
> >> pass-through succeed if we didn't do
> >> XENMAPSPACE_gmfn_range hypercall in pci_setup() with 4G memory.
> >>
> >
> > Yep. Please send patches when you figure it out!
> >
> >
> > -- Pasi
> >
> >
> >
> >> --Weidong
> >>
> >> > -- Pasi
> >> >
> >> > >
> >> > >
> >> > >    Any ideas about this issue? Thanks in advance.
> >> > >
> >> > >
> >> >
> >> > > _______________________________________________
> >> > > Xen-devel mailing list
> >> > > Xen-devel@xxxxxxxxxxxxx
> >> > > http://lists.xen.org/xen-devel
> >>
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxx
> > http://lists.xen.org/xen-devel

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