Running a Fedora Core DomU on a Debian Etch Dom0
Sat Sep 06 2008
At Sirius, we have a number of boxes running Xen which we use to run virtuals for infrastructure & testing. Now it came up a couple of weeks ago that we needed to test some packages under FC8, and I was about to install the OS under Qemu when I realised that since Fedora have been shipping Xen kernels for a while, there must be a way getting a working FC8 DomU running on our existing Debian Etch Dom0. Unfortunately it wasn’t as straightforward as I was hoping (with small snippets of information all over the place), so I’ve included the instructions below in the hope that someone else will find them useful.
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Obtain a FC8 installation image
The easiest way to do this was to use the Rinse utility to create a FC8 image in a suitable directory on the virtualisation host.
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Chroot to the installation image directory
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Install the Xen DomU kernel
Rinse didn’t install the Xen kernel by default and so I did a
yum install kernel-xen
to install the kernel image and initrd. These we then copied outside of the chroot so they could be loaded by the dom0. -
Rebuild the initrd
The initrd built by Rinse appeared to have missing filenames within its startup script, however re-building the initrd within the chroot appeared to resolve the issue. I also found it was necessary to explicitly include the Xen drivers for disk/network access within the initrd by including
--with=xenblk --with=xennet
on the initrd command line. -
Change the TTY numbers in /etc/inittab
Xen seems to use TTYs named
xvcX
rather thanttyX
, so I altered the mingetty entries in/etc/inittab
to usexvcX
instead. -
Add devpts to
/etc/fstab
Fedora kernels seem to need devpts, and Rinse didn’t add the required entry to
/etc/fstab
. Hence I added the following line:devpts /dev/pts devpts gid=5,mode=620 0 0
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Create the domU & enjoy
With all the above changes in place, I was able to successfully start the Fedora Core 8 Xen kernel under a Debian Etch Dom0. I hope that this article will save people time if they are required to use a mixed distribution Xen environment.