I had xen2 working on a SMP kernel for dom0 but UP for domU and it worked 
well enough. Netbsd on both. Not sure domU can be MP from what I read.

-Ober


On Tue, 12 Sep 2006, Luke Crawford wrote:

> Date: Tue, 12 Sep 2006 18:15:07 -0700 (PDT)
> From: Luke Crawford <lsc@prgmr.com>
> To: Andreas Wrede <andreas@planix.com>
> Cc: i.vari@niwa.co.nz, port-xen@NetBSD.org
> Subject: Re: Netbsd XEN nothing I can boot in
> 
> On Tue, 12 Sep 2006, Andreas Wrede wrote:
>> Try booting xen with 'nosmp' (and maybe 'noapic') on the 'kernel 
>> (hd0,a)/xen.gz...' line in grub's menu.lst. Right now NetBSD does not 
>> support multiple CPUs to well.
>
> now, I'm running a Debian dom0 and a NetBSD3.1-rc2 domU.  Of course, the xen 
> and the hardware is dual cpu;   I put nosmp in the root= line on the domU 
> config file.  It seems to work,  a nosmp NetBSD domu with a SMP debian dom0. 
> I'd be interested in the details of how the smp/nosmp nature of the xen 
> kernel and the dom0 effect the domU, if anyone has information or links.
>