Xen "Boot loader didn't return any data!"

[ramin.honary]

I've been Googling for about 4 hours now, and have nothing. I am trying to boot an ISO image of Ubuntu 10.04 server on my Ubuntu 11.10 host. I used "apt-get" to install all the Xen stuff, setup my /etc/grub.d, and rebooted.

I created a VM configuration file "/etc/xen/ubuntu-10.04-server":

name = "ubuntu-10.04-server"
memory = 1024
disk = [ "file://home/ramin/ubuntu-10.04.3-server-i386.iso,hdc:cdrom,r"
       , "phy:/dev/sda6,hda1,w"
       , "file://opt/xen-ubuntu-10.04-server.swap,hda2,w"
       ]
vif  = [ "bridge=xenbr0" ]
bootloader = "/usr/lib/xen-4.1/bin/pygrub"
boot = "d"
dhcp = "dhcp"

Then I run "xm create -c":

bash-4.1# xm create -c ubuntu-10.04-server
Using config file "/etc/xen/ubuntu-10.04-server".
Error: Boot loader didn't return any data!

Here is the output of "/var/log/xen/xend.log":

[2012-01-13 00:38:21 1677] DEBUG (XendDomainInfo:3071) XendDomainInfo.destroy: domid=32
[2012-01-13 00:38:21 1677] DEBUG (XendDomainInfo:2406) No device model
[2012-01-13 00:38:21 1677] DEBUG (XendDomainInfo:2408) Releasing devices
[2012-01-13 00:38:21 1677] ERROR (XendDomainInfo:108) Domain construction failed
Traceback (most recent call last):
  File "/usr/lib/xen-4.1/bin/../lib/python/xen/xend/XendDomainInfo.py", line 106, in create
    vm.start()
  File "/usr/lib/xen-4.1/bin/../lib/python/xen/xend/XendDomainInfo.py", line 474, in start
    XendTask.log_progress(31, 60, self._initDomain)
  File "/usr/lib/xen-4.1/bin/../lib/python/xen/xend/XendTask.py", line 209, in log_progress
    retval = func(*args, **kwds)
  File "/usr/lib/xen-4.1/bin/../lib/python/xen/xend/XendDomainInfo.py", line 2838, in _initDomain
    self._configureBootloader()
  File "/usr/lib/xen-4.1/bin/../lib/python/xen/xend/XendDomainInfo.py", line 3285, in _configureBootloader
    bootloader_args, kernel, ramdisk, args)
  File "/usr/lib/xen-4.1/bin/../lib/python/xen/xend/XendBootloader.py", line 215, in bootloader
    raise VmError, msg
VmError: Boot loader didn't return any data!

It's frustrating because the error message doesn't really say anything about why the problem is occurring. Does anyone have any ideas?

If someone can even suggest what diagnostics I can do to get an idea of why the error is occurring, I would be grateful.

[ramin.honary]

So, in all the Googling I did, I found most people recommend installing something called the "xen-tools" package to facilitate installation of VM instances. I haven't installed it yet because it is not in Ubuntu's "main" package repository, plus I am trying to avoid some of the dependencies it has.

Ubuntu does provide "virt-manager" in its main repository, but I found two problems with it. First, it expects Xen to have a UNIX socket open so userland software can issue commands to it. I thought Xen provided this socket by default, but apparently not. When I first started "virt-manager", it gave me an error message:

Unable to open a connection to the Xen hypervisor/daemon.

Verify that:
 - A Xen host kernel was booted
 - The Xen service has been started

unable to connect to 'localhost:8000': Connection refused

After some more Googling, I found the answer: one must modify "/etc/xen/xend-config.sxp" file and uncomment these lines:

 # (xend-unix-server no) <-- uncomment, change to "yes"
(xend-unix-server yes)

 # (xend-unix-path /var/lib/xend/xend-socket) <-- uncomment, don't change
(xend-unix-path /var/lib/xend/xend-socket)

Then reboot, and now "virt-manager" launches without a problem.

Ubuntu sure has made it a pain in the ass to install Xen. How ironic, I though "Zen" was the opposite of a pain in the ass. Anyway I've already submitted this as a bug.

My new problem is figuring out how to get "virt-manager" to install an instance of Ubuntu server from a CD-ROM. Here is how NOT to do it:

virt-install \
--name='ubuntu-10.04-server' \
--ram=1024 \
--cdrom='/ubuntu-10.04.3-server-i386.iso' \
--os-variant='ubuntulucid' \
--disk=path='/dev/sda9' \
--filesystem=source='/home,target=/home' \
--console='pty,target_type=xen'

ERROR    Paravirtualized guests cannot install off cdrom media.

Does anyone one know what I should do from here? I have the install media, obviously, but I don't know how to boot using that media. There must be a way.

And my original question still stands: what is the damn "xmdomain.cfg" file supposed to look like, so I can boot an ISO image of the Ubuntu server boot CD and install it to the VM's disk device.

[vipinlal]

When you are using virt-manager to create a VM, the configuration file will be automatically created by virt-manager. No need to edit it manually.

>>ERROR Paravirtualized guests cannot install off cdrom media.

This error because you have created a paravirtualized guest and trying to install it using CDROM, which is not supported. You need to have installation tree structure exported through nfs or http for installing paravirtualized guest. You can use CDROM to install fully virtualized guest, if your host has virtualization support in CPU. (check in bios for it)