Re: [Xen-users] Match between Dom0 and DomU PV

[Chris 'Xenon' Hanson <xenon@xxxxxxxxxxxxxx>]

Fajar A. Nugraha wrote:
> Newer kernels and hypervisors should be able to work even when their
> version are not exact match, provided that:
> - they are new enough (Xen >= 3.1 should be enough)
> - they are architecturally compatible (64bit hypervisor can work with
> 64bit and 32bit PAE kernel, but 32bit hypervisor can only work with
> 32bit kernel)

  Ok. That's what I assumed.

>> Here, I have a Debian 5 x64 (2.6.26-2-xen-amd64) Dom0 and Ubuntu 8.04
>> x86-32 (2.6.24-23-xen) DomU. It seems to be known that that 2.6.24-23-xen is 
>> the problem,
>> and 2.6.28.8 is recommended.
> Really? by 2.6.28.8 I assume you mean pv_ops kernel. It works, but not
> all features of -xen kernel is available on pv_ops kernel yet. See
> http://wiki.xensource.com/xenwiki/XenParavirtOps

  Well, I was basing that on the reply from Markus Schonhaber on 5/12:

"I have neither found the root of the problem nor a solution. But
replacing the domU's Ubuntu kernel by a self-compiled recent vanilla
kernel (2.6.28.8) with domU support is a workaround that lets the domU
run stable since 54 days now - previously one week was the most I could
get for uptime."

> Have you tried the suggestions on the previous thread? from my
> experience Debian's kernel (or RHEL's kernel, if you're feeling
> adventurous) works quite nicely as domU kernel for Ubuntu. Plus you
> don't have to compile anything.

  I wasn't quite sure how to safely fetch Debian 5's x86-32 kernel (and any 
supporting
files needed) from my x64 Debian box without messing things up. I'd be 
_thrilled_ to sort
things out without having to recompile a kernel, as this machine intentionally 
doens't
have dev tools installed on it (in Dom0 or DomU).

>>  I also have little experience with x64 Linux -- I presume I can't just boot 
>> my Ubuntu
>> 8.04 (x86-32) DomU using the 2.6.26-2-xen-amd64 kernel my Dom0 uses, because 
>> that DomU is
>> an entirely 32-bit Ubuntu, and the Dom0 is a 64-bit Debian kernel, right?
> It should work, but you might have some problems with kernel
> module-userland interaction (e.g. using iptables).
> Try http://packages.debian.org/lenny/linux-image-2.6.26-2-xen-686

  I grabbed that, but just dropping it in in place of the existing kernel made 
the DomU
boot very angry. The gist of it is:

WARNING: Couldn't open directory /lib/modules/2.6.26-2-xen-686: No such file or 
directory
FATAL: Could not open /lib/modules/2.6.26-2-xen-686/modules.dep.temp for 
writing: No such
file or directory

Here's the config with the old kernel commented out:

#kernel      = '/etc/xen/kernels/alpha/vmlinuz-2.6.24-23-xen'
kernel      = '/etc/xen/kernels/alpha/vmlinuz-2.6.26-2-xen-686'
ramdisk     = '/etc/xen/kernels/alpha/initrd.img-2.6.24-23-xen'

So, I'm guessing I'd need a 26-2 initrd.img too. I'll have to look and see what 
package I
might be able to get that from.

-- 
Chris 'Xenon' Hanson, omo sanza lettere                  Xenon AlphaPixel.com
PixelSense Landsat processing now available! http://www.alphapixel.com/demos/
"There is no Truth. There is only Perception. To Perceive is to Exist." - Xen

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