Xen domU fails to start with kernel panic

Question

My dom0 is Gento 3.3.2, the kernel is compiled with Xen support. And I am planing to use the same kernel to boot my domU.

This is my domU configuration file:

  1 vif = [ 'bridge=xenbr0' ]
  2 vcpus = 1
  3 uuid = "c1d751ba-e228-45e6-b7a8-01895e88a815"
  4 root = "/dev/xvda ro"
  5 name = "Gentoo"
  6 memory = 512
  7 kernel = "/boot/kernel-3.3.2-gentoo"
  8 extra = "4 console=hvc0"
  9 disk = [ 'phy:/dev/vg/gentoo,xvda,w' ]

the /dev/vg/gentoo is a LV. After I ran xl create -c gentoo.cfg, the guest started and stopped with the following error (only the last few lines):

[    0.122019] netconsole: network logging started
[    0.122180] Root-NFS: no NFS server address
[    0.122186] VFS: Unable to mount root fs via NFS, trying floppy.
[    0.122280] VFS: Cannot open root device "xvda" or unknown-block(2,0)
[    0.123056] Please append a correct "root=" boot option; here are the available partitions:
[    0.123056] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)

Answer 1

It's been a while since I've used Xen, but when you say you've compiled your kernel with xen support do you have the xenblk driver/module? I think it's something like CONFIG_XEN_BLKDEV_FRONTEND in your .config. Have you tried any other xen configurations just to see if they work? For example, using the tap:aio interface?