HOW TO: install Lucid/10.04 LTS on Xen 3.1 with xen-tools/debootstrap

**ac4000** · May 12th, 2010

Following are the steps I took to install Lucid on Xen using Steve Kemp's fantastic xen-tools package. I did some cursory research and couldn't find any Lucid templates, so I modified the existing templates. It's not very elegant, but it appears to have gotten the job done (many VMs running for days now without problems).

UPDATE: The dev version of xen-tools, and presumably debootstrap, has lucid/pygrub support, so pretty soon these instructions will be redundant (i.e., you might take a look at those versions as well/instead).

System:

dom0 running Debian Lenny with kernel 2.6.26-2-xen-amd64 and Xen 3.2 (community, of course)
domU Ubuntu 10.04 LTS

Copy files from edgy.d template (latest available) to lucid.d.
Code:
```
cp -r /usr/lib/xen-tools/edgy.d /usr/lib/xen-tools/lucid.d
```

Link debootstrap gutsy profile (latest available) to lucid.

Code:

ln -s /usr/share/debootstrap/scripts/gutsy /usr/share/debootstrap/scripts/lucid

Link current xen directory (many tools expect to find it here).
Code:
```
ln -s /usr/lib/xen-3.2-1 /usr/lib/xen
```
Link pygrub to /usr/bin (many tools expect to find it here).
Code:
```
ln -s /usr/lib/xen/bin/pygrub /usr/bin/pygrub
```

Modify /etc/xen-tools/xm.tmpl so that it lists root device first (pygrub requires this to work properly); replace the entire section following "# Disk device(s)." and preceding "# Hostname" with:

Code:

{
  for ( my $i = 0; $i <= $#PARTITIONS; $i++ )
  {
      if ( $PARTITIONS[$i]{'mountpoint'} eq '/' )
      {
          $OUT .= "root        = '/dev/$device" . ($i + 1) . " ro'\n";
      }
  }
  $OUT .= "disk        = [\n";
  for ( my $i = 0; $i <= $#PARTITIONS; $i++ )
  {
      if ( $PARTITIONS[$i]{'mountpoint'} eq '/' )
      {
            $OUT .= "                  '$PARTITIONS[$i]{'imagetype'}$PARTITIONS[$i]{'image'},$device" . ( $i + 1 ) .",w',\n";
      }
  }
  for ( my $i = 0; $i <= $#PARTITIONS; $i++ )
  {
      if ( $PARTITIONS[$i]{'mountpoint'} ne '/' )
      {
            $OUT .= "                  '$PARTITIONS[$i]{'imagetype'}$PARTITIONS[$i]{'image'},$device" . ( $i + 1 ) .",w',\n";
      }
  }
  $OUT .= "              ]\n";
}

Replace the entire contents of /usr/lib/xen-tools/lucid.d/30-disable-gettys with the following (to work with non-event.d, non-inittab, hvc0 setup):

Code:

#!/bin/sh
#
#  This script comments out all virtual terminals which aren't on the
# first console - that must remain so that 'xm console ...' works
# correctly.
#
# Steve
# --
# http://www.steve.org.uk/
#
# Updated for Lucid; DDS/ABC
#

prefix=$1


#
#  Source our common functions
#
if [ -e /usr/lib/xen-tools/common.sh ]; then
    . /usr/lib/xen-tools/common.sh
else
    . ./hooks/common.sh
fi


#
# Log our start
#
logMessage Script $0 starting

#
#  Remove the links for upstart
#
rm ${prefix}/etc/init/tty[!1].conf


#
#  Are we using an alternative serial device?
#
if [ ! -z "${serial_device}" ]; then

    serial_device=`basename ${serial_device}`

    # Let the user know.
    logMessage "Replacing default serial device (tty1) with ${serial_device}; having destroyed the rest"

    # replace existing device.
    mv ${prefix}/etc/init/tty1.conf ${prefix}/etc/init/${serial_device}.conf
    sed -i -e s/tty1/${serial_device}/ ${prefix}/etc/init/${serial_device}.conf

    # make sure that it is allowed to login.
    echo $serial_device >> ${prefix}/etc/securetty
fi

#
#  Log our finish
#
logMessage Script $0 finished

Create /etc/xen-tools/role.d/pygrub, and set its executable bit, with the following contents, to allow booting from the guest kernel, which is what I prefer (if you prefer to boot from dom0-supplied kernels, you can skip this); the script is based on Wejn's tremendously helpful pygrub script, which I modified to install a newer kernel version and the linux-virtual package; note that you'll need to use this role and the pygrub role:

Code:

#!/bin/sh
#
#  Configure the new image to be suitable for booting via pygrub
#
# Wejn
# --
# http://wejn.org/
#
# Updated for Lucid; DDS/ABC
#


prefix=$1


#
#  Source our common functions - this will let us install a Debian package.
#
if [ -e /usr/lib/xen-tools/common.sh ]; then
    . /usr/lib/xen-tools/common.sh
else
    echo "Installation problem"
fi


#
#  Update APT lists.
#
chroot ${prefix} /usr/bin/apt-get update
 

#
#  Install the packages
#
set -e
installDebianPackage ${prefix} perl
installDebianPackage ${prefix} libklibc
installDebianPackage ${prefix} klibc-utils
installDebianPackage ${prefix} initramfs-tools
#installDebianPackage ${prefix} linux-image-2.6-xen-amd64
installDebianPackage ${prefix} linux-virtual

# Force initrd if none exists
echo ${prefix}/boot/initrd* | grep -q 2\\.6
if [ $? -ne 0 ]; then
        chroot ${prefix} update-initramfs -c -k `ls -1 ${prefix}/lib/modules/ | head -n 1`
fi

# Generate grub menu.lst
LNZ=`basename \`ls -1 ${prefix}/boot/vmlinuz*|tail -n 1\``
RD=`basename \`ls -1 ${prefix}/boot/initrd*|tail -n 1\``
mkdir -p ${prefix}/boot/grub
cat - <<-EOF > ${prefix}/boot/grub/menu.lst
default         0
timeout         5

title           Debian/Ubuntu
root            (hd0,0)
kernel          /boot/$LNZ root=/dev/xvda2 ro
initrd          /boot/$RD
EOF

Be sure to edit your /etc/xen-tools/xen-tools.conf as appropriate (e.g., changing the distribution to lucid) and use --role=udev,pygrub when you run xen-create-image; also, comment out the kernel and initrd lines so xm defaults to pygrb; finally, you may also want to add the line "serial_console = hvc0" (no quotes) so that Xen provides the correct console based on the 30-disable-gettys script, above. (A diff between my working xen-tools.conf and the package version is at post #3, below). Note that this will create a VM with a root user (and password that you set if you enabled that option in xen-tools.conf). I've written a few roles to secure the installation, including disabling the root password, which I'll try to post if I have some time.

I can produce diffs, if there's interest in the above. Please jump in and modify the above, add to it, etc. As I said, it's not a very elegant solution, but I needed it quickly. (I also must apologize in advance if I'm not able to keep up with questions here, if there are any--we're a bit slammed with work at the moment.)

**tbaptista** · May 14th, 2010

Great tutorial. Thanks.

I have one question.

The cfg file created for the domU had the normal kernel and initrd lines and not the pygrub bootloader line. I had to change that to enable pygrub.

And also the console stops working midway the boot sequence. After the following lines:

Begin: Running /scripts/init-bottom ...
Done.
mountall: Disconnected from Plymouth

Do you have any idea why? I tried to put in the cfg file the extra parameter console=hvc0, but it didn't make any difference.

Best Regards,
Tiago Baptista

**ac4000** · May 14th, 2010

Tiago, thanks for pointing that out. In the tutorial, I missed the part where you need to comment out the kernel and initrd lines in xen-tools.conf, which causes xm to boot with pygrub (no need to call it explicitly). I will update the above.

As for the console disconnection, I have the line

Code:

serial_console = hvc0

in xen-tools.conf, but this is supposed to be the default. Try it and see if it changes things and, if it does, I will update the above.

Here's the diff between the package version and my xen-tools.conf:

Code:

--- xen-tools.conf      2008-09-29 19:08:11.000000000 -0400
+++ /etc/xen-tools/xen-tools.conf       2010-05-10 13:00:39.000000000 -0400

-# lvm = skx-vg
+lvm = xenvg

-swap   = 128Mb    # Swap size
+swap   = 512Mb    # Swap size

-dist   = etch     # Default distribution to install.
+dist   = lucid    # Default distribution to install.

-# passwd = 1
+#passwd = 1

-kernel      = /boot/vmlinuz-`uname -r`
-initrd      = /boot/initrd.img-`uname -r`
+# Undefined, to use pygrub.
+#kernel      = /boot/vmlinuz-`uname -r`
+#initrd      = /boot/initrd.img-`uname -r`

-# arch=[i386|amd64]
+arch=amd64

-# serial_device = hvc0 #default
+serial_device = hvc0 #default
+# serial_device = xvc0

-# disk_device = xvda #default
+disk_device = xvda #default

**tbaptista** · May 14th, 2010

Yes, that solved both problems. Thanks.

Best,
Tiago

**umuro** · May 18th, 2010

Followed the advice above. I get
Error: (2, 'Invalid kernel', 'xc_dom_find_loader: no loader found\n')

Any ideas?

**ac4000** · May 18th, 2010

Make sure pygrub is linked properly to /usr/bin/pygrub ... that's the first thing that jumps to mind. You could also try running pygrub directly and pointing it at the image or LV to make sure it's finding something to boot. If that doesn't work, would you mind posting the generated config file?