[Qemu-devel] PCI access virtualization

[Michael Renzmann <mrenzmann@otaku42.de>]

Hi all.

Disclaimer: I'm quite new to things like virtual machines, and even
half-baked when it comes to QEMU. I'm aware that my idea might be
absurd, but still it's worth a try :)

I'm wondering if it would be possible to modify QEMU such that VMs could
access PCI devices on the host system. And, if it would be possible at
all, how much work this would be.

Background: I'm one of the developers of MadWifi, which is a linux
driver for WLAN cards based on Atheros chipsets. QEMU could be a great
help in testing distribution-specific issues, as well as issues related
to SMP operation. The only downside is that it's not easily possible to
emulate the necessary WLAN hardware.
Now, if it would be possible to allow a VM to access physical PCI
devices on the host, it could make use of non-emulated hardware for this
purpose. Even more, thanks to the SMP emulation that recently went into
QEMU, it would be possible to test the compatibility of the driver with
SMP systems, even if the host is just a UP system.

I vaguely heard of a feature present in Xen, which allows to assign PCI
devices to one of the guests. I understand Xen works different than
QEMU, but maybe is would be possible to implement something similar.

Any comments appreciated, thanks in advance.

Bye, Mike