Re: [Xen-users] Fc5 guest on FC6 host

[Hilton Day <xlot@xxxxxxxxxxxxxxxxx>]

Robin,

The kernel-xen package is PAE-enabled kernel in FC5 too I believe, so 
you need to upgrade the kernel in your domU to that. (however, the 
kernel-xen0 and kernel-xenU packages, as you've found, aren't PAE)
I see 2 alternatives here (in both cases, back up the domU image first 
using dd or similar):
1.  Try the FC5 to FC6 upgrade process by running xenguest-install with 
FC6, against the FC5 disk image.  I'm not sure if the upgrade process works
or 2.  More involved, but using rpm to install the PAE-enabled 
kernel-xen from FC5.. read on :)
You can do that by mounting the domU's filesystem - either using lomount 
if you're using a file-based image, or kpartx if you're using an 
LVM-based image.
e.g. to mount the partitions in an Logical volume called "domU1" which 
resides in a physical volume "LogVol00", I'd use something like:
kpartx -av /dev/LogVol00/domU1

It'll then create mapper entries in /dev/mapper/ to each partition which 
you can in turn mount inside the dom0.  (if the domU's virtual disk is 
also LVM-based, you can use kpartx again on the entry in /dev/mapper 
that corresponds to the LV partition - although this can get messy if 
you've left volume names as the default in all dom's).
You'll need to mount the root partition, and /boot and maybe also create 
a /proc filesystem (mount -t proc proc /mnt/domUroot/proc).
Fetch yourself the rpm for kernel-xen from an updates repository, then 
use rpm with the --root flag to upgrade the kernel.. e.g. something like
rpm -ivh --root /mnt/domUroot kernel-xen-2.6.18-1.2200.fc5.i686.rpm

Once that completes, you should be able to unmount all the partitions, 
and use "kpartx -dv /dev/LogVol00/domU1" to remove the mapper entries.  
Once they're gone, try booting the domU and it should work.
Man pages for each of the commands above will help if you get stuck on 
syntax or semantics :)
HTH

Hilton.

Robin Bowes wrote:
> Hi,
>
> I have a test box running FC5 (kernel-xen0-2.6.18-1.2200.fc5) with a FC5
> guest system.
>
> I upgraded the host to FC6, and am now running the FC6 Xen kernel
> (kernel-xen-2.6.18-1.2798.fc6).
>
> I am now unable to run the guest system. I see the following msgs in the
> log:
>
> ERROR: Non PAE-kernel on PAE host.
> ERROR: Error constructing guest OS
>
> I've googled and found this [1]:
>
> Q. When creating a guest the message "Invalid argument" is displayed.
>
> A. This usually indicates that the kernel image you are trying to boot
> is incompatible with the hypervisor. This will be seen if trying to run
> a FC5 (non-PAE) kernel on FC6 (which is PAE only), or if trying to run a
> bare metal kernel.
>
> [1] http://fedoraproject.org/wiki/FedoraXenQuickstartFC6
>
>
> I'm guessing the fix is to upgrade the guest O/S to FC6 too. However, I
> am currently unable to boot it as it won't boot under FC6 and the FC6
> version of Xen won't run under the FC5 kernel.
>
> Any suggestions as to how I might fix this? Or did I basically do things
> in the wrong order, i.e. should I have upgraded the guest O/S first?
>
> Thanks,
>
> R.
>
>
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> http://lists.xensource.com/xen-users
>   

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