Re: [Xen-users] ubuntu and debian guests cannot find or mount root partition

[David Della Vecchia <ddv@xxxxxxxxxxxxxxxx>]

On Thu, Nov 10, 2011 at 1:15 PM, Mike Viau <viaum@xxxxxxxxxxxxxxx> wrote:

On Thu, 10 Nov 2011 15:42:03 +0000 <adamgold@xxxxxxxxxxx> wrote:

I've recently installed xen 4.1 but am having problems getting the guests up and running (I'm using ubuntu 11.10 for dom0 and have tried the same distro plus squeeze for guests).  It seems they can't find the root partition.  I've left most of the defaults in xen-tools.conf, just changing the name of the volume group (I'm testing an lvm installation) and used the debootstrap creation process.  I went through the following steps:

1) xen-create-image --hostname vm1 --role=udev --ip=[   ]
2) xm new /etc/xen/vm1.cfg
3) xm start vm1

After I started the guest and connected to the console it dropped to a busy box shell.  Here's the last part of the output prior to the bb shell (I can provide more):

=================================================
[    0.277228] EFI Variables Facility v0.08 2004-May-17
[    0.277490] TCP cubic registered
[    0.277613] NET: Registered protocol family 10
[    0.278147] NET: Registered protocol family 17
[    0.278168] Registering the dns_resolver key type
[    0.278282] registered taskstats version 1
[    0.288490]   Magic number: 1:252:3141
[    0.288517] /build/buildd/linux-3.0.0/drivers/rtc/hctosys.c: unable to open rtc device (rtc0)
[    0.288526] BIOS EDD facility v0.16 2004-Jun-25, 0 devices found
[    0.288531] EDD information not available.
[    0.288996] Freeing unused kernel memory: 984k freed
[    0.289247] Write protecting the kernel read-only data: 10240k
[    0.293653] Freeing unused kernel memory: 20k freed
[    0.294225] Freeing unused kernel memory: 1400k freed
Loading, please wait...
[    0.339223] udevd[78]: starting version 173
Begin: Loading essential drivers ... done.
Begin: Running /scripts/init-premount ... done.
Begin: Mounting root file system ... Begin: Running /scripts/local-top ... done.
Gave up waiting for root device.  Common problems:
 - Boot args (cat /proc/cmdline)
   - Check rootdelay= (did the system wait long enough?)
   - Check root= (did the system wait for the right device?)
 - Missing modules (cat /proc/modules; ls /dev)
ALERT!  /dev/xvda2 does not exist.  Dropping to a shell!
=================================================

Following the suggestions in the shell:
- 'cat /proc/cmdline' = 'root=/dev/xvda2 ro' which is the correct root partition (or should be at least)
- 'cat /proc/modules', no output
- ls /dev - no sign of xvda or any of its partitions

Finally, here's the config file:

=================================================
kernel      = '/boot/vmlinuz-3.0.0-12-generic'
ramdisk     = '/boot/initrd.img-3.0.0-12-generic'
vcpus       = '1'
memory      = '256'
root        = '/dev/xvda2 ro'
disk        = [
                  'phy:/dev/vgxen1/vm1-disk,xvda2,w',
                  'phy:/dev/vgxen1/vm1-swap,xvda1,w',
              ]
name        = 'vm1'
vif         = [ 'ip=[   ],mac=00:16:3E:12:C7:A0' ]
>on_reboot   = 'restart'
on_crash    = 'restart'
=================================================

Any advice would be much appreciated.

- Can you try using the sda1/2 instead of xvda1/2 for the disk and swap device?

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Does the initrd have the xenblk drivers included? I know when i try to spin up Ubuntu 11.04 domU's on my debian dom0 i have to include the xenbus_probe_frontend module in the /etc/initramfs-tools/modules file so it gets included in the initrd on generation. I use pv-grub for my domU's so it all exists on the domU but its the same principle.

-DDV

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