Fedora xen - Nov 2006 - guest boot error: could not find filesystem ''/dev/root''

Hi,
I have installed FC5 (didn''t have FC6 media in hand) into a
loop-mounted
file.
I used yum --installroot=/path/ .
I have copied modules of the xen kernel into the guest filesystem.
Everything went ok.
But the kernel does not boot. I use these params in xmdefconfig:

kernel = "/boot/vmlinuz-2.6.18-1.2798.fc6xen"
ramdisk = "/boot/initrd-2.6.18-1.2798.fc6xen.img"

(AFAIK there is no xenU kernels anymore).
The guest boot ends with these lines:
Mounting root filesystem.
mount: could not find filesystem ''/dev/root''
Setting up other filesystems.
Setting up new root fs
setuproot: moving /dev failed: No such file or directory
no fstab.sys, mounting internal defaults
setuproot: error mounting /proc: No such file or directory
setuproot: error mounting /sys: No such file or directory
Switching to new root and running init.
unmounting old /dev
unmounting old /proc
unmounting old /sys
switchroot: mount failed: No such file or directory
Kernel panic - not syncing: Attempted to kill init!


This problem was presented in this mailing list a while ago:
"This is the "blkfront bug", where the initrd scripts try to
mount the root filesystem before the vbd disks are attached
to the guest domain. "

with a remark that it should be fixed now (kernel-xen-2.6.17-1 with a 
revision number >= 2558)
Is it back again or I do something stupid here?
Can this be caused by something else?

thanks for any advice

-- 
Tomas Kouba