[Xen-users] 4.0.1, Debian Squeeze, and p[yv]grub

[Simon Hobson <linux@xxxxxxxxxxxxxxxx>]

The system is a new install of Debian Squeeze, with Xen 4.0.1 (latest 
stable package for Debian). I'm trying to get guests booted with 
pygrub, or even better pvgrub but it's not working for me.
First off, as far as I can tell, pvgrub isn't in Debian - and it 
won't be as it's been rejected. Does anyone know if this is being 
worked on ?
As for pygrub, that's failing as well. Apart from hitting the known 
bug that stops GRUB2 from installing on the guest (had to pull a 
later version down from Testing), starting a domain gives the error :
>    Error: Boot loader didn't return any data!
/var/log/xen/xend.log contains :

> Traceback (most recent call last):
>   File "/usr/lib/xen-4.0/lib/python/xen/xend/XendDomainInfo.py", 
> line 104, in create
>     vm.start()
>   File "/usr/lib/xen-4.0/lib/python/xen/xend/XendDomainInfo.py", 
> line 469, in start
>     XendTask.log_progress(31, 60, self._initDomain)
>   File "/usr/lib/xen-4.0/lib/python/xen/xend/XendTask.py", line 209, 
> in log_progress
>     retval = func(*args, **kwds)
>   File "/usr/lib/xen-4.0/lib/python/xen/xend/XendDomainInfo.py", 
> line 2820, in _initDomain
>     self._configureBootloader()
>   File "/usr/lib/xen-4.0/lib/python/xen/xend/XendDomainInfo.py", 
> line 3266, in _configureBootloader
>     bootloader_args, kernel, ramdisk, args)
>   File "/usr/lib/xen-4.0/lib/python/xen/xend/XendBootloader.py", 
> line 215, in bootloader
>     raise VmError, msg
> VmError: Boot loader didn't return any data!

Following a hint I came across, I tried manually calling pygrub with :
>  /usr/lib/xen-default/bin/pygrub --args="root=/dev/xvda1 ro" 
> /dev/vgmain/ipv6root
And got these errors :

> Using <class 'grub.GrubConf.Grub2ConfigFile'> to parse /boot/grub/grub.cfg
> WARNING:root:Unknown directive load_video
> WARNING:root:Unknown directive terminal_output
> Traceback (most recent call last):
>   File "/usr/lib/xen-default/bin/pygrub", line 669, in <module>
>     chosencfg = run_grub(file, entry, fs, incfg["args"])
>   File "/usr/lib/xen-default/bin/pygrub", line 549, in run_grub
>     g = Grub(file, fs)
>   File "/usr/lib/xen-default/bin/pygrub", line 205, in __init__
>     self.read_config(file, fs)
>   File "/usr/lib/xen-default/bin/pygrub", line 413, in read_config
>     self.cf.parse(buf)
>   File "/usr/lib/xen-4.0/bin/../lib/python/grub/GrubConf.py", line 
> 402, in parse
>     self.add_image(Grub2Image(title, img))
>   File "/usr/lib/xen-4.0/bin/../lib/python/grub/GrubConf.py", line 
> 318, in __init__
>     _GrubImage.__init__(self, title, lines)
>   File "/usr/lib/xen-4.0/bin/../lib/python/grub/GrubConf.py", line 
> 87, in __init__
>     self.reset(lines)
>   File "/usr/lib/xen-4.0/bin/../lib/python/grub/GrubConf.py", line 
> 103, in reset
>     self._parse(lines)
>   File "/usr/lib/xen-4.0/bin/../lib/python/grub/GrubConf.py", line 
> 98, in _parse
>     map(self.set_from_line, lines)
>   File "/usr/lib/xen-4.0/bin/../lib/python/grub/GrubConf.py", line 
> 328, in set_from_line
>     setattr(self, self.commands[com], arg.strip())
>   File "/usr/lib/xen-4.0/bin/../lib/python/grub/GrubConf.py", line 
> 106, in set_root
>     self._root = GrubDiskPart(val)
>   File "/usr/lib/xen-4.0/bin/../lib/python/grub/GrubConf.py", line 
> 57, in __init__
>     self.disk = str
>   File "/usr/lib/xen-4.0/bin/../lib/python/grub/GrubConf.py", line 
> 70, in set_disk
>     self._disk = int(val[2:])
> ValueError: invalid literal for int() with base 10: 'ev/xvda1'

Based on the last line of that, I tried an experiment and edited the 
script. AFAICS, the line in question is trying to extract a number 
from a device name, so I tried changing it from
> self._disk = int(val[2:])
to
> self._disk = int(val[9:])
I can then get the GRUB menu, and then quits - putting :
> linux (kernel /var/run/xend/boot/boot_kernel._IqLoQ)(ramdisk 
> /var/run/xend/boot/boot_ramdisk.XUIE7W)(args 
> "root=UUID=0fdd2127-ff17-4bd4-b1b8-08fd8b27ec9a ro  quiet 
> root=/dev/xvda1 ro")
to the terminal - but not starting the guest.

Trying to start the guest with "xm create -c ipv6" gives :

> Started domain ipv6 (id=3)
>                           [    0.204334] PCI: Fatal: No config space 
> access function found
> [    0.251557] i8042.c: No controller found.
> Loading, please wait...
> mount: No such device
> W: devtmpfs not available, falling back to tmpfs for /dev
> Gave up waiting for root device.  Common problems:
>  - Boot args (cat /proc/cmdline)
>    - Check rootdelay= (did the system wait long enough?)
>    - Check root= (did the system wait for the right device?)
>  - Missing modules (cat /proc/modules; ls /dev)
> ALERT!  /dev/xvda1 does not exist.  Dropping to a shell!
> (initramfs)
So it seems to have started the guest, but not with the right setup.

If I change the boot settings back to using kernel= and ramdisk= 
gives me a working guest again.
Any hints ?

Bear in mind that I'm trying to keep it entirely with packaged 
software, and 4.1 is only in the Debian unstable repository at the 
moment.
--
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

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