[Fedora-xen] howto? - run a different OS on FC5-xen

[Chris McKeever]

> Actually, that's exactly what I did in my howto, a FC4 guest on a FC5 host.
>
> http://mitopia.net/index.php/Xen_3.0.2_Setup

Mito - I went through your HOWTO -
Excellently put together, really got me on track for some things -
ran into some items, not sure if I just followed it wrong, or if there
are inconsistencies...

It seems that you compiled xen to create a xenU and xen0 kernel, but
for both your instances, you use the full compiled xen kernel (which
can be used by either prov or unpriv)
>From the README:

"It will build the xen binary (xen.gz),
   and a linux kernel and modules that can be used in both dom0 and an
   unprivileged guest kernel (vmlinuz-2.6.x-xen),"

CONF:
# Your domain's name
name = "it-works"
# Kernel to use
kernel = "/boot/vmlinuz-2.6.16-xen"

GRUB:
title Xen 3.0.2 / XenLinux 2.6.16
       root (hd0,0)
       kernel /xen-3.0.gz dom0_mem=65536
       module /vmlinuz-2.6.16-xen ro root=/dev/md2


If you are just using the full kernel - you can theoretically take out
both compile steps for building your xen0 and xenU kernels (Compile
dom0 Kernel | Compile domU Kernel) - This is actually the path I took
and why I noticed this - it would up being easier to build the one
universal kernel -- plus I ran into some compile issue when just doing
the xen0 compile.

I am not sure the performance benefit of using a stripped down xenU
kernel for the guests, but for my current needs - it got me up and
running using the full compile - from the README:

"vmlinuz-2.6.x-xen0 and
   vmlinuz-2.6.x-xenU. These are smaller builds with just selected
   modules, intended primarily for developers that don't like to wait
   for a -xen kernel to build. "

With that, I also learned that FC5 by default uses lvm (?) for the
root partition, so I needed to create the initrd - outside of that, I
dont think I would have needed that step.

For your guest, you list some xen configs (which are documented, but I
couldn't get them to work):
vif=[ 'ip=10.0.0.2' ]
dhcp="off"
netmask="255.255.0.0"
gateway="10.0.0.254"
hostname = "mail"

One thing to note, is that for this type of config your guest kernel needs
to be compiled with:
IP: kernel level autoconfiguration
http://tlug.up.ac.za/old/guides/lkcg/net_ipv4.html

I however could not get xen to pass these as kernel command line
arguments, and actually needed to pass them using this format (extras
variable):
ip=<client-ip>:<server-ip>:<gw-ip>:<netmask>:<hostname>:<device>:<autoconf>

That let me boot and set the network options from the config file.


Finally - building your image with QEMU -
I didnt completely walk through this, as I quickly learned your host
machine needs X (would be great if anaconda could have been kicked
off) -- but the good news is that, after a source xen install, setting
the initrd so it sees that logical drive, I was very easily able to
get the FC4 image to boot from jailtime.org

So - for the most part I have a fully functional xen-fc4 within fc5
and outside of your inconsistency with the kernel definitions in GRUB
and the XEN conf -- great job, and thanks!!


> That, and NAT networking, but you don't have to do those steps if you
> don't need them...
>
> Mito
>
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