Daily Archives: November 8, 2007

Xen Gutsy Links

A post full of links and unsorted info about using Xen on Ubuntu Gutsy Gibbon, so that I don’t forget. (This lot has taken ~2 days to collect…) May make a full howto sometime… probably not though, as my boss knows this stuff better than I. Xen is pretty cool though…

https://help.ubuntu.com/community/Xen (useless for gutsy…)

The Xen console doesn’t work (xm console <domU>), network works once, and then never again… Going to paste this here as its in a pastebin, not sure when it will expire… (Have tweaked slightly, snipped a couple of things out, added couple of things in)

>> OK, I have made a little progress on this.  I mounted my VM image on a
>> loopback and chroot'd to it.  I opened /etc/init.d/hwclock.sh
>> and /etc/init.d/hwclockfirst.sh and added the following to the top of each
>> file:
>>   exit 0

ALSO SEE: http://lists.cvsrepository.org/xen-tools/Jul07/0332.html

sudo xm create -c </path/to/config/file>


# Ever-increasing network device names?

# Just disable the correspondent udev rules by deleting/renaming your
/etc/udev/rules.d/<NUMBER>persistant-net.rules. (number was 70 for us...)

guest# mv /etc/udev/rules.d/{,.}z25_persistent-net.rules

# And then make sure your vif (in your instance config file) contains your mac
# address like:
vif = ['ip=,mac=<random valid mac addy>']

Just be sure to stop the instance (domU), and then restart (re-create) it again when needs be…

Also, when in the Xen console, try hitting enter before using the escape sequence (CTL +]) if it’s not working. Sometimes it enters into the console after the “login:” prompt has been printed, and doesn’t seem to pick up that its just had a new connection…
The ALSO SEE link: http://lists.cvsrepository.org/xen-tools/Jul07/0332.html

Using Serial console & xen console (serial console conflicts with xen console):

/boot/grub/menu.lst stuff, to enable us to use a serial console as well as xen:

serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1
terminal --timeout=2 serial console

Goes in the top of your menu.lst, outside the automagic sections…

## additional options to use with the default boot option, but not with the
## alternatives (These options are not used with the Xen Kernel!)
# defoptions=quiet splash console=ttyS0,115200n8

For the default kernel, (NOT the xen kernel).
Goes inside the AUTOMAGIC section of your menu.lst, adding to the options already there.

## Xen Linux kernel options to use with the default Xen boot option
# xenkopt=console=tty0 console=ttyS0,115200n8 xencons=ttyS9

Note the xencons=ttyS9. Use a serial port (ttyS<No.>) that doesn’t already exist.

Your Xen kernel definition should look something like this, after you’ve run “update-grub”:

title           Xen 3.1 / Ubuntu 7.10, kernel 2.6.22-14-xen
root            (hd0,0)
kernel          /xen-3.1.gz
module          /vmlinuz-2.6.22-14-xen root=/dev/mapper/volume-root ro console=tty0 console=ttyS0,115200n8 xencons=ttyS9
module          /initrd.img-2.6.22-14-xen

The guys on irc ##xen @ freenode are really helpful…