Re: [Xen-users] xen3 domU on xen4 dom0

[Henrik Langos <hlangos-xen@xxxxxxxxxxxxxx>]

On Wed, Feb 09, 2011 at 02:17:10PM +0100, Wolfgang Grossbauer wrote:
> On 08.02.2011 17:26, Henrik Langos wrote:
>> On Tue, Feb 08, 2011 at 03:26:50PM +0000, Todd Deshane wrote:
>>> On Tue, Feb 8, 2011 at 2:17 PM, Wolf Grossi<wg@xxxxxxxxxxxxxx>  wrote:
>>>> Greetings!
>>>>
>>>> Trying to to run a xen3 domU on a xen4 dem0 I run into problems.
>>>>
>> ...
>>>> With
>>>> xm create -c M08
>>>> I get the following error:
>>>>
>>>> XEN1:/etc/xen/vm # Error: (2, 'Invalid kernel', 'elf_xen_note_check: ERROR:
>>>> Xen will only load images built for Xen v3.0\n')
>>>>
>>>> I do not uderstand the above error: the kernel to be loaded *is* a xen-3.0
>>>> kernel and should be taken from domU:/boot.
>>>>
>>>> Now I have the following questions:
>>>> 1) Can I run xen-3 domU's on a xen-4 dom0?
>>
>> Yes. I am running a Debian Squeeze Xen 4.0.1 Hypervisor and 
>> 2.6.32-5-xen-amd64 dom0.
>>
>> On that I run a couple of older PVM machines that have an 2.6.26-2-xen-686 
>> kernel.
>> That is a 32bit kernel compiled for xen 3.2-1.
>>
>> Tomorrow I'll try to get my old Etch VMs there too. (2.6.18 32bit domU made 
>> for Xen 3.0.3)
>>
>>>> 2) If yes (hope so :-), what's wrong with the above install/config,
>>>>    or what have I missed?
>>
>> I guess your pygrub doesn't find the right kernel on your VM's disk image.
>>
>> Try to mount the image in dom0, copy the kernel and initrd to /boot/foo/
>>
>> Edit your config file /etc/xen/vm/M08 and replace
>>
>>   bootloader      = '/usr/lib/xen-default/bin/pygrub'
>>
>> with
>>
>>   #bootloader      = '/usr/lib/xen-default/bin/pygrub'
>>   root = '/boot/foo/vmlinuz-blah'
>>   ramdisk= '/boot/foo/initrd-blah'
>>
>> Don't forget to umount the VM's disk image and try again
>> xm create /etc/xen/vm/M08
>>
>> Good luck :-)
>>
>>>
>>> You need the "top" Xen version to run as an HVM guest on the bottom
>>> Xen. So, for your case, make your Xen3 Xen domU an HVM domain. That
>>> should work.
>>>
>>> Hope that helps.
>>>
>>> Thanks,
>>> Todd
>>
>> AFAIK pygrub is only for PVM, isn't it? So I assume that Wolf tries
>> to get an older PVM guest to run on a relatively recent hypervisor/dom0
>>
>> cheers
>> -henrik
>>
>
>
> Yes, exactly;
> I'm trying to run a xen3 paravirt guest (32 Bit)
> on a xen4 (64 Bit).

I am doing the same thing here. It even works with _very_ old 2.6.18 kernels
made for xen 3.0.3. Tried it yesterday and it works like a charm.

> I applied your suggestions, however still the same problem:
>
> xm create M08
> Using config file "/etc/xen/vm/M08".
> Error: (2, 'Invalid kernel', 'elf_xen_note_check: ERROR: Xen will only  
> load images built for Xen v3.0\n')
>
>
> M08 config for xm:
> ---
> root = '/boot/vmlinuz-2.6.11.4-20a-xen'
> ramdisk= '/boot/initrd-2.6.11.4-20a-xen'
> disk= [ 'file:/root/M08.raw,xvda,w' ]
> ---

Aaaaahhh. My bad!  It is not "root" but "kernel".

It should have been

kernel = '/boot/vmlinuz-foo'
ramdisk= '/boot/initrd-foo'
root = '/dev/xvda2 ro'
disk= [ 'file:/root/M08.raw,xvda,w' ]

But wait a second ... 2.6.11 ??? What is this? The dark ages? ;-)

I am pretty sure that 2.6.11 was not a xen 3 kernel.

cheers
-henrik

PS: Please use "reply-to-all" to have your reply also on the list.
Maybe somebody else will find this in the mailing list archive
before trying to run a 2.6.11 linux on a 4.0 hypervisor.

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