Running 32bit guests in a 64bit Dom= XEN system is not a problem.
Just copy over the lib/modules from the Dom0 server and it works.
There are a few things however you should be aware of:
- 32bit utilities (userland tools) can't modify kernel parameters
In real world this involves problems with these components:
- Iptables won't work
- IPSEC tunnels (openswan) won't work
- (x)ntp will also have problems
When you need to have these functionality in a DOmU guest you are out of chance.
Your only options are:
- Use 64bit DomU as well
- Install these tools in the Dom0 environment
- Use the hardware virtualization