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XEN: How to CD-boot fully-virtualized DomU's after initial installation

This document (3156432) is provided subject to the disclaimer at the end of this document.

Environment

Novell SUSE Linux Enterprise Desktop 10 Support Pack 1
Novell SUSE Linux Enterprise Server 10 Support Pack 1
Novell Open Enterprise Server 2 (Linux based)
Novell openSUSE 10.2
Novell openSUSE 10.3

Situation

After the initial installation, a DomU needs to be booted from CD.

Resolution

Booting to a CD after installing a fully virtualized DomU is straight forward and simple, more so than para-virtualized DomU's. This method can be used to boot a SuSE Linux Enterprise 9 or 10 computer into a rescue system.

For the purposes of this TID, replace SLES10 with the name of your DomU. The "hda" is a hard-drive, "hdc" is a CD-ROM device that uses an ISO image.


  1. Shutdown the DomU guest
  2. Go to /etc/xen/vm
  3. Locate the configuration file for the DomU
  4. Copy the configuration file; the copy will be used instead of the original file
    cp /etc/xen/vm/sles10 /etc/xen/vm/sles10-cdboot
  5. Open the file for editing
  6. Change the name of the DomU in the configuration file. This can be done by locating the name="..." directive
    name="sles10-cdboot"
  7. Delete the UUID line
  8. Locate the disk definition line. It may look like this:
    disk=['file:/root/SLES.iso,hdc:cdrom,r','file:/var/lib/xen/images/sles10-1/disk0,hda,w',]
  9. It this example, the CD-ROM is "hdc" and the hard disk is "hda". The drive numeration for fully virtual booting follows the traditional DOS drive enumeration; that is, hard disk start at "C" and continue up, followed by CD-ROM devices. The default boot is to "C", or the first hard drive. In order to boot from the CD, locate the boot="..." directive. It should look like this:
    boot="c"
  10. Change it to DOS enumeration identifier. In our example, their is one hard disk and one CD-ROM, so the DOS enumeration will be "d"
    boot="d"
  11. Save and close the file
  12. Since we only want to temporarily boot to the CD-ROM, we are not going to reload the configuration file, but rather discard the configuration after we boot. This is done with the "xm create" command.
    xm create SLES10-cdboot
  13. Access the terminal/virtual monitor through "virt-manager", VNC or the typical method
  14. After you are done repairing or booting from CD, shutdown the DomU. Boot the DomU normally.
  15. The SLES10-cdboot file can then be used anytime with the "xm create SLES10-cdboot" command to boot the DomU using the CD.


Example CD-Boot File

The following is an example of a CD-boot DomU configruation file.

ostype="sles10"
name="sles10-cdboot"
memory=512
vcpus=1
on_crash="destroy"
on_poweroff="destroy"
on_reboot="restart"
localtime=0
builder="hvm"
extid=0
device_model="/usr/lib/xen/bin/qemu-dm"
kernel="/usr/lib/xen/boot/hvmloader"
boot="d"
disk=['file:/root/mini.iso,hda:cdrom,r',
'file:/var/lib/xen/images/sles10-1/disk0,hdc,w',]
vif=['mac=00:16:3e:37:bf:64,model=rtl8139,type=ioemu',]
vnc=1
vncunused=1
apic=0
acpi=1
pae=1

Additional Information

Shortcut:
If the CD-Rom is already defined in the configuration file, then you can pass the "boot=d" as a parameter and not need to use the temporary file. For example
xm create SLES10 boot=d
or
xm start SLES10 boot=d

Disclaimer

This Support Knowledgebase provides a valuable tool for NetIQ/Novell/SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:3156432
  • Creation Date:17-MAR-08
  • Modified Date:27-APR-12
    • SUSESUSE Linux Enterprise Desktop
      SUSE Linux Enterprise Server

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