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

[Mirko Raasch]

Hi,

i tried some pci devices in windows guest, but there are some problems.

If i only use one pci card, i can install the driver in the guest and 
the device is working.

If i want to use two or more pci devices in the guest, they are not 
usable, it means i can install the
drivers, but the devices are not active in the device manager (yellow* 
exclamation mark)*

If i install two ore more pci devices and pass through only one of them, 
its also not usable in the
guest (yellow *exclamation mark)*

Exists there some limitations in the usage of "PCI Passthrough"?

(sorry for my bad english)

Greetings
Mirko

> Hi Mirko,
>
> On Sun, 2009-06-28 at 17:46 +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
>>
>> 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.
>>     
>
> I'm afraid this is purely a limitation with the current code in qemu:
>
>     /* For now, we just refuse to do a secondary bus reset                                                                    
>      * if there are other devices/functions behind the bus.                                                                   
>      * In future, we could allow it so long as those devices                                                                  
>      * are not in use by the host or other guests.                                                                            
>      */
>     if (pciBusContainsOtherDevices(conn, dev)) {
>         VIR_WARN("Other devices on bus with %s, not doing bus reset",
>                  dev->name);
>         return -1;
>     }
>
> We also have a bug tracking this issue:
>
>   https://bugzilla.redhat.com/499678
>
> Fixes welcome! :-)
>
> Cheers,
> Mark.
>
>
>