[libvirt] More then one pci device possible with libvirt and pci passthrough?

Daniel P. Berrange berrange at redhat.com
Sun Jun 28 15:55:05 UTC 2009

On Sun, Jun 28, 2009 at 05:46:51PM +0200, Mirko Raasch wrote:
> Hi,
> i want to use more then one pci card in my debian guest.
> But when i start the guest, the log says:
>  libvirtd: 15:44:55.459: warning : pciTrySecondaryBusReset:483 : Other
> devices on bus with 0000:05:01.0, not doing bus reset

IIUC, what libvirt is complaining about is that there are other devices
in the PCI bus which are not associated with this guest, and thus there
is no way to safely reset the device you are trying to assign, without
endangering the host OS or other guest OS

> With "/usr/bin/qemu-system-x86_64 -m 512 -name test -hda
> /media/vm/test.img -boot c -vnc :2 -k de -pcidevice host=05:01.0
> -pcidevice host=05:02.0 -pcidevice host=05:03.0" there seems to be no
> problems.
> How can i start my guest with three pci devices passed through and libvirt?

The difference is that when you launch QEMU manually there is no
checking for whether the PCI devices are in use by other guests,
or by the host OS. So while it may launch QEMU, it is not running
safely, and eg, if your guest  OS does a PCI bus reset it could
kill/harm your host OS.

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