I've been wanting to have a play with Xen for quite some time, but have a
pathological dislike of compiling kernels, so hadn't gotten around to it. So
needless to say, I'm very very (very very) pleased to see Xen 3.0 packages
in Debian now, and so spent some time today having a fiddle.
Frankly, I'm very pleased with how easy it's been to get everything going.
Mad props to Steve Kemp for xen-tools, it makes the ease of
creating a new DomU approach that of falling off a log. A big thanks also to
the Debian kernel team for packaging this stuff up at last as well.
So, here's what I did:
I installed linux-image-2.6.16-1-xen-686 and xen-hypervisor-3.0-i386, along with the aforementioned xen-tools
The linux-image-2.6.16-1-xen-686 kernel package doesn't create an initrd by
default, so I created one by hand with mkinitramfs-kpkg.
I put this in my GRUB config:
module /boot/vmlinuz-2.6.16-1-xen-686 root=/dev/hda1 ro console=tty0
There's a couple of kernel images available that mention Xen, the
aforementioned linux-image-2.6.16-1-xen-686 and also linux-image-2.6.16-1-xen-vserver-686. Unfortunately the package
descriptions are the same as the stock 2.6.16 kernel package, and I
initially formed the opinion that one was the Dom0 kernel and the other was
the DomU kernel. It turns out that the linux-image-2.6.16-1-xen-686 will
operate as either, and the vserver one will work as a DomU (I haven't tried
it as a Dom0).
I'm currently using file-backed storage, but I want to switch to directly
using LVM once I get the hang of things. I created the filesystem for the
--hostname testvm \
--size 2Gb --swap 128Mb --memory 96Mb \
--fs ext3 --dir /srv \
--cache yes --dist etch \
--mirror http://mirror.linux.org.au/debian \
--kernel /boot/vmlinuz-2.6.16-1-xen-vserver-686 \
The one problem with this script is it puts SCSI (i.e. /etc/sda)
devices in /etc/fstab, but refers to them as /dev/hda
devices everywhere else. So to avoid a kernel panic on booting the DomU, I
had to mount the image that was created and edit the /etc/fstab
file to fix this up. I also needed to add vif = [ '' ] to get an
eth0 interface to exist in the DomU instance. There's some other stuff you
put here to use a consistent MAC address, rather than a per-instance-boot
I also found I needed to edit /etc/xen/xend-config.sxp to use
network-bridge instead of network-dummy and vif-bridge. I found I needed to
reboot as just restarting xend afterwards royally messed with the networking
That was about it. Creating an instance of the VM then worked. Making sure
the loop kernel module is loaded helps avoid some obscure errors.