[Fedora-xen] FC5 -- with new "development" Xen kernels/xend

[Chris Lalancette]

Russell McOrmond wrote:
> 
>   Just for kicks I tried the kernel-xen, xen and dependencies from the 
> 'development' yum repository.  When trying to create the XenU's it gave 
> me a "Error: (22, 'Invalid argument')".
> 
>   With FC5 there was a xen0 kernel for the Xen0 and a xenU kernel that 
> was put in each XenU.   I believe that for the development branch (and 
> FC6) that something different is being done, with the Xen0 using a 
> 'kernel-xen' package: kernel-xen-2.6.17-1.2647.fc6  .  I'm gathering 
> that the XenU kernels are also different now (like what happened with 
> the FC4 to FC5 switch), meaning I can't continue to use the xenU kernels 
> I currently have installed.
> 
> 
>   When I mentioned this issue on Bugzilla (In a different context of 
> waiting for a new FC5 kernel with a specific patch 
> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=199944 ), Herbert 
> Xu mentioned I need to have XenU kernels with the PAE patch.
> 
>   Does anyone know which Fedora kernels to be putting in the XenU's if 
> I'm wanting to use the new "development" xen and kernel-xen?
> 

Russell,
     If you look in /var/log/xend-debug.log, I believe you will see something along the lines of "Trying to start non-PAE kernel on PAE hypervisor".  FC5 was originally put out with kernel-xen0, a non-PAE hypervisor/dom0, and kernel-xenU, a non-PAE domU kernel.  During development for FC6, it was decided to 1) consolidate our -xen0 and -xenU into a single -xen kernel, and 2) make all Xen kernels PAE enabled.  Since Xen does not support booting non-PAE paravirt kernels on a PAE hypervisor, or vice-versa, you will not be able to boot up "older" FC5 guests on a development FC6 kernel.
     That being said, we also decided to make a PAE Xen variant for FC5, also named kernel-xen.  What I would suggest is to boot up the "older" FC5 kernel-xen0, and then boot up your guest(s) with the "older" kernel-xenU.  Then do the following in the guest:

1)  Edit /etc/modprobe.conf to make sure you have
      alias eth0 xennet
      alias scsi_hostadapter xenblk

2)  Run "yum install kernel-xen".  That will grab the PAE variant of the FC5 kernel.

Once you have done this, you should be able to shutdown the guest, reboot the host into the FC6 "development" kernel, and then start up your guests, making sure to choose the kernel-xen kernel.

I hope that helps.

Chris Lalancette