Mounting /dev/root on /root failed: no such device

[Tom H]

On Thu, Jun 30, 2011 at 8:19 PM, Mohammad Hedayati
<hedayati.mo at gmail.com> wrote:
>
> I'm using Ubuntu 11.04 and I managed to compile Xen 4.0.1 on it using
> this tutorial:
> http://blog.davidwolinsky.com/2010/12/installing-xen-401-and-testing-on.html
> Everything went fine, but using this menuentry:
> menuentry 'Ubuntu GNU/Linux, with Xen 4 and Linux 2.6.32.41' --class
> ubuntu --class gnu-linux --class gnu --class os --class xen {
>        insmod ext2
>        set root='(hd0,2)'
>        echo            'Loading Xen 4 ...'
>        multiboot       (hd0,2)/boot/xen.gz console=vga
>        echo            'Loading Linux 2.6.32.41 ...'
>        module          (hd0,2)/boot/vmlinuz-2.6.32.41 root=/dev/sda2
> nopat ro console=tty0
>        echo            'Loading initial ramdisk ...'
>        module          (hd0,2)/boot/initrd.img-2.6.32.41
> }
> but while booting I get:
> mount: Mounting /dev/root on /root failed: no such device
> mount: Mounting /dev on /root/dev/ failed: no such file or directory
> mount: Mounting /sys on /root/sys failed: no such file or directory

Two thoughts.

Your initrd might be bad. Delete and re-create it with
"update-initramfs -d -k $(uname -r)" and "update-initramfs -c -k
$(uname -r)".

You used ext4 and didn't compile ext4 support into the kernel.