Fedora xen - Sep 2006 - FC5 -- with new "development" Xen kernels/xend

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?

-- 
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On Thu, Sep 21, 2006 at 10:58:45AM -0400, 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'')".
This (utterly useless[1]) error message usually indicates that the guest
kernel you are trying to boot is incompatible with your hypervisor. 
ie, you tried to boot a baremetal kernel as a guest, or in this case
you tried to boot a PAE enabled kernel on a non-PAE hypervisor.
>   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?
If its called ''kernel-xen'' then its PAE enabled, if its called
kernel-xenU
then its non PAE enabled.  

So you must either use kernel-xen for both host & guest, or use kernel-xen0
and kernel-xenU. You can''t mix use of kernel-xen with kernel-xenU

Regards,
Dan.

[1] I''m working on patches to upstream Xen tools to give sensible error
    reporting instead of the current method which just returns -EINVAL
    everywhere :-(
-- 
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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