When I first downloaded Windows 8 and the Windows Server 8 Edition, I haven’t been able to boot the iso and install these new Operating systems on Xenserver. I needed to install it on a physical machine, Hyper-v or vmware workstation (and then P2V or VTV it to my XenServer). Not really handy. Then I found a very cool tip on Thomas Koetzing blog : http://www.thomaskoetzing.de/index.php?option=com_content&task=view&id=344&Itemid=254
To fix the issue you have to set parameter on the XenServer comand line interface (CLI). Create a VM with a Win7 template and copy the virtual machine UUID from the general tab in XenCenter or use xe vm-list in the CLI. Next you run the command
Once you’ve done this modification, you’ll be able to install Windows 8 (all edition) within the vm. Have fun testing out the new Windows 8 OS from Microsoft.