On Tuesday 03 March 2009, Christoph Hellwig wrote:
I've been trying to move setup from kvm 72 in debian testing to the current
qemu CVS. The setup is using 7 virtio_blk disks and used to work on the
old setup, but with current qemu the kernel (current Linus' HEAD from a few
days ago) hangs when trying to setup the irq routing for the virtio_pci
devices:
virtio pci 0000:00:06.0: can't derive routing for PCI INT A
virtio pci 0000:00:06.0: PCI INT A: no GSI - using IRQ 9
IIRC this is partly a bios issue. Real PIIX3 based systems never have more
than ~5 PCI slots, so it doesn't have interrupt routing for more devices.
There are two solutions: Fix the bios to handle machines with large numbers of
PCI slots, or have create multifunction PCI devices so lots of virtio
instances don't use so many virtual PCI slots.