Re: PCI passthrough error
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Quoting Jaap Winius <jwinius@xxxxxxx>:
... Anyway I guess now it's USB passthrough or bust. Or get a board with an IOMMU.
In case anyone is ever interested, I did eventually manage to solve this problem with a wrapper script, although not exactly the way David Wragg explains in his blog.
With Debian squeeze, the problem is that when using virt-manager to configure USB passthrough, it allows you to select a USB device based on its vendorID and productID combination, which happens to be exactly what I need. However, when passing the selected device on to the virtual machine, the kvm command it generates is only for the bus/device combination that the selected device is currently using. That, combined with the lack of any hot-plug support is what was preventing me from getting my system to work.
The solution for me was simply to bypass any methods using virt-manager or the virsh editor to define the devices for USB passthrough. Then, instead of using the wrapper script to modify any devices already defined, I use it to add all of the devices I need. It looks like this:
#!/bin/shexec /usr/bin/kvm `echo $* | sed 's/-vga std/-vga std -usbdevice host:auto:*.*:0c93:1772 -usbdevice host:auto:*.*:0c93:1771/'`
Incidentally, this script has to have the same name as the executable, which on Debian squeeze is /usr/bin/kvm. So, I called this script /usr/local/bin/kvm, and not /usr/local/bin/qemu-kvm, like in Wragg's blog.
Anyway, the above script allows me to start up the virtual machine with only one (or none) of the devices attached. Then the theory is that the Windows device driver loads some firmware into the device, which causes it to change its product ID from 1772 to 1771, as well as its device number. Crucially, my wrapper script doesn't care about this device number change and the new device is also passed through to the virtual machine. As far as I can tell, the Windows software continues to work as expected.
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