Pkg xen devel - Nov 2008 - Pygrub problem

Hello,

I would like to use the kernel in the domU, so that a user can install
it's own kernel. While starting the domU with pygrub I get the following
error: "Error: Boot loader didn't return any data!"

This is the configfile of the domU:
--------------
#
# Configuration file for the Xen instance lenny.vandervlis.nl, created
# by xen-tools 3.9 on Sun Oct 19 15:46:03 2008.
#

#
#  Kernel + memory size

# kernel      = '/boot/vmlinuz-2.6.26-1-xen-amd64'
# ramdisk     = '/boot/initrd.img-2.6.26-1-xen-amd64'
memory      = '128'

#
#  Disk device(s).
#
root        = '/dev/sda2 ro'
disk        = [
                  'phy:/dev/volume0/lenny.vandervlis.nl-swap,sda1,w',
                  'phy:/dev/volume0/lenny.vandervlis.nl-disk,sda2,w',
              ]

#
#  Hostname
#
name        = 'lenny.vandervlis.nl'

#
#  Networking
#
vif         = [ 'ip=91.198.178.30,mac=00:16:3E:E9:A1:DD' ]

#
#  Behaviour
#
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'

extra = "console=xvc0 xencons=xvc0"
bootloader="/usr/lib/xen-3.2-1/bin/pygrub"
----------------

When I look into the xend-log I see this:
-------------
[2008-11-26 13:51:31 2705] DEBUG (XendDomainInfo:84)
XendDomainInfo.create(['vm', ['name',
'lenny.vandervlis.nl'], ['memory',
'128'], ['on_poweroff', 'destroy'],
['on_reboot', 'restart'],
['on_crash', 'restart'], ['vcpus', 1],
['on_xend_start', 'ignore'],
['on_xend_stop', 'ignore'], ['bootloader',
'/usr/lib/xen-3.2-1/bin/pygrub'], ['bootloader_args',
'-q'], ['image',
['linux', ['root', '/dev/sda2 ro'], ['args',
'console=xvc0
xencons=xvc0']]], ['device', ['vbd', ['uname',
'phy:/dev/volume0/lenny.vandervlis.nl-swap'], ['dev',
'sda1'], ['mode',
'w']]], ['device', ['vbd', ['uname',
'phy:/dev/volume0/lenny.vandervlis.nl-disk'], ['dev',
'sda2'], ['mode',
'w']]], ['device', ['vif', ['ip',
'91.198.178.30'], ['mac',
'00:16:3E:E9:A1:DD']]]])
[2008-11-26 13:51:31 2705] DEBUG (XendDomainInfo:1618)
XendDomainInfo.constructDomain
[2008-11-26 13:51:31 2705] DEBUG (balloon:132) Balloon: 131884 KiB free;
need 2048; done.
[2008-11-26 13:51:31 2705] DEBUG (XendDomain:443) Adding Domain: 15
[2008-11-26 13:51:31 2705] DEBUG (XendDomainInfo:1703)
XendDomainInfo.initDomain: 15 256
[2008-11-26 13:51:31 2579] DEBUG (XendBootloader:100) Launching
bootloader as ['/usr/lib/xen-3.2-1/bin/pygrub',
'--args=root=/dev/sda2
ro console=xvc0 xencons=xvc0',
'--output=/var/run/xend/boot/xenbl.21780', '-q',
'/dev/volume0/lenny.vandervlis.nl-swap'].
[2008-11-26 13:51:31 2705] ERROR (XendBootloader:171) Boot loader didn't
return any data!
[2008-11-26 13:51:31 2705] ERROR (XendDomainInfo:440) VM start failed
Traceback (most recent call last):
  File "/usr/lib/xen-3.2-1/lib/python/xen/xend/XendDomainInfo.py",
line
420, in start
    XendTask.log_progress(31, 60, self._initDomain)
  File "/usr/lib/xen-3.2-1/lib/python/xen/xend/XendTask.py", line 209,
in log_progress
    retval = func(*args, **kwds)
  File "/usr/lib/xen-3.2-1/lib/python/xen/xend/XendDomainInfo.py",
line
1705, in _initDomain
    self._configureBootloader()
  File "/usr/lib/xen-3.2-1/lib/python/xen/xend/XendDomainInfo.py",
line
2064, in _configureBootloader
    bootloader_args, kernel, ramdisk, args)
  File "/usr/lib/xen-3.2-1/lib/python/xen/xend/XendBootloader.py",
line
172, in bootloader
    raise VmError, msg
VmError: Boot loader didn't return any data!
------------

What will be wrong?  I think the bootloader is launched wrong, but why?

In the domU I have a kernel, initrd, menu.lst and device.map.

With regards,
Paul van der Vlis.




-- 
http://www.vandervlis.nl/

On Wed, 2008-11-26 at 14:14 +0100, Paul van der Vlis
wrote:
>  Launching
> bootloader as ['/usr/lib/xen-3.2-1/bin/pygrub',
'--args=root=/dev/sda2
> ro console=xvc0 xencons=xvc0',
> '--output=/var/run/xend/boot/xenbl.21780', '-q',
> '/dev/volume0/lenny.vandervlis.nl-swap'].
It's interesting that it appears to be looking in the -swap device for
the kernel, seems unlikely to work. I guess there is some way to make it
select a more sensible disk. I usually use a single device with a
partition so I can mark one of them bootable, I'm not sure how it works
in the multiple device pretending to be partitions way of thinking.

Does switching your disk statement make it work? e.g.
        disk        = [
                         
'phy:/dev/volume0/lenny.vandervlis.nl-disk,sda2,w',
                         
'phy:/dev/volume0/lenny.vandervlis.nl-swap,sda1,w',
                      ]
This seems more like a workaround than a fix though.

This code in /usr/lib/xen-3.2-1/lib/python/xen/xend/XendDomainInfo.py
looks suspect
                    disks = [x for x in self.info['vbd_refs']
                             if
self.info['devices'][x][1]['bootable']]
        
                    if not disks:
                        msg = "Had a bootloader specified, but no disks are
bootable"
                        log.error(msg)
                        raise VmError(msg)
        
                    devinfo = self.info['devices'][disks[0]]
It goes to the trouble of making a list of bootable devices but then
ignores it and goes back to self.info['devices']. I'd guess that the
last line here should be:
		devinfo = disks[0]
Although I don't know how you make bootable be true. You may find
bringing this up on xen-devel useful.

(two questions I wrote before I noticed -swap, probably not relevant now
but:

Does running this command by hand, possibly without the -q to make it
more verbose, tell you anything.

Is there a /boot/grub/menu.lst within the guests root?)

Ian.
-- 
Ian Campbell

purpitation, n.:
	To take something off the grocery shelf, decide you
	don't want it, and then put it in another section.
		-- "Sniglets", Rich Hall & Friends