On Wed, Jan 21, 2009 at 2:48 PM, Mark McLoughlin <markmc@redhat.com> wrote:
(This is all getting offtopic for fedora-xen, we should really move to
fedora-virt)

On Wed, 2009-01-21 at 14:28 +0100, Jan ONDREJ (SAL) wrote:
>  virtio_net works well, but I have trouble to boot from virtio_blk.
>
> I can add second disk as virto block device, but I can't boot from
> first disk.

When switching from IDE to virtio, you need to first build a new initrd
in the guest with e.g.:

 $> mkinitrd --with virtio_pci --with virtio_blk -f /boot/initrd-$(kernelversion) $(kernelversion)

You only need to do this once. After that, if a new kernel is installed
while you're booted off a virtio disk, then mkinitrd will include the
modules automatically.

You will also need to specify /dev/vdX on the kernel  root= line and make sure your init script inside your initrd triggers the virtio drivers at boot so that the /dev/vdX are created.

--
Emre