[Fedora-xen] Move from Fedora 8 dom0s to F12/F13 dom0s with Xen 4.0.x questions

[fcxen user]

I would like to try to move some dom0s from Fedora 8 to Fedora 12/13/Xen 4.0, 
but I had a few questions. Some of these are probably repeats so I apologize 
in advance.

* I use "virsh define" to create the VM configurations using virsh xml, and I 
assume that virsh/libvirtd won't work on a recent 2.6.32/33/3x kernel and Xen 
4.0.0
Is there a way to extract the xm style configuration values from the running 
VMs? Or a file somewhere so I can pull out/copy the VM configs for use on the 
new machine or is there another way to do that? It has been since about Fedora 
Core 5 that I used the xm style configs so I don't have that in my head like 
many on this list do.

* I am using plain disk files for the storage for each VM, I understand that 
Xen 4.0 has the ability to use these now with the correct kernel. Is that the 
case? Would I be able to use my current (F10-F12) VMs as is?

* Although Pasi, Michael, Dale and others have been very generous with their 
information, testing and development, I am not completely clear on all the 
steps required to get a working F12/F13/ Xen 4.0.X dom0 with 2.6.32/33/3x 
kernel starting from a base F12/F13 system install. If someone can point out 
where to find different parts I would be grateful and would be willing to 
consolidate them into a single blob if that doesn't already exist. I looked at 
some of the wiki some on the xen wiki but I get a bit of choice overload from 
those pages - you can use this kernel or that kernel or...

* If this were to work, would I see a performance increase or (hopefully not) 
decrease for vanilla F10-F12 domUs (apache, etc) on the same hardware going 
from Xen 3.1.4 on F8 to Xen 4.0.x on F12/F13 on Intel 5400/5500 based servers?

Thanks for any help.


One of the other reasons I want to upgrade is because I can no longer add VMs 
with virt-install command line. I constantly get:

libvir: Xen Daemon error : GET operation failed: xend_get: error from xen daemon:
virDomainLookupByID() failed GET operation failed: xend_get: error from xen 
daemon:

Even after upgrading to libvirtd 0.4.6-1.fc8 and even immediately after 
rebooting the dom0 - which seemed to be a workaround for others that I read 
about having this problem. I realize this is not the libvirtd list but a 
couple of the replies to this problem that I have seen are along the lines of 
"it is not a libvirt problem". And If it is not too painful to get the F12/F13 
dom0s working with my old VMs, I hope to just forget all about this :)