Fedora and Xen: A Quick Start Guide

[David Hollis]

On Tue, 2005-01-25 at 00:03 -0500, Jeremy Katz wrote:
> 
> Next, let's create a file to use as the backing for our Fedora install.
> For example purposes, I'll create one of a size of 1 GB.
>   dd if=/dev/zero of=/root/fedora.img bs=1M count=1024

To make a sparse file, I used:
dd if=/dev/zero of=fedora.img bs=1M count=1 seek=1024

This way, my file looked like 1GB, but only allocated space upon use.

> Now, create an ext3 filesystem on this image.
>   mke2fs -F -j /root/fedora.img
> You should now be able to mount your new temporary rootfs on a temporary
> mountpoint, say /mnt
>   mount -o loop /root/fedora.img /mnt
> Now, we can install whatever basesystem we want into this chroot.  Make
> sure that your yum configuration points to a valid repository.  Then,
> decide what group(s) you want to install.  I'd recommend starting with
> Base (or for the space constrained, Core, but this is more difficult).
> Then, run
>   yum --installroot=/mnt -y groupinstall Base
> 

Cool trick!  Didn't know that I could do that!  I did find that I needed
to 'rpm --root /mnt --import <various RPM-GPG-KEYs> to make yum happy.
I also needed to create /mnt/var/cache/yum so that it could write
the .gpgkeyschecked.yum file.  I suppose that if I turned off gpg
checking, I would have been fine.

> Now, go get some coffee and have a snack.  It's going to take a little
> while :-)
> 

Using rawhide as of this morning, I had dep issues with dmraid (needs to
be rebuilt against new device-mapper) and stunnel (needs words).  I
excluded dmraid and stunnel and the install went ok.

> Come back and if everything went okay, you'll have a minimal install
> in /mnt.  Now, for the ugly part, we need to set up some basic bits on
> the filesystem that have to be different for xen right now.  These
> include a) creating some required device nodes in /dev
> since we're not using an initrd  and b) setting up an /etc/fstab
>   for i in console null zero ; do MAKEDEV -d /mnt -x $i ; done
> 

for i in console null zero; do MAKEDEV -d /mnt/dev -x $i ; done

Otherwise, those device files end up in / instead /dev on the filesystem
image.

> For the /etc/fstab, something simple like the following should work
> /dev/sda1               /                       ext3    defaults
> 1 1
> none                    /dev/pts                devpts  gid=5,mode=620
> 0 0
> none                    /dev/shm                tmpfs   defaults
> 0 0
> none                    /proc                   proc    defaults
> 0 0
> none                    /sys                    sysfs   defaults
> 0 0

Would it be necessary to have /sys in fstab?  The initscripts mount it
automagically themselves.  Haven't performed any testing myself to
validate with a Xen config.

-- 
David Hollis <dhollis at davehollis.com>
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