LINUX DISTRIBUTIONS: WHAT TO TEST AFTER PACKAGING
mkinitrd and/or mkinitramfs should be able to generate bootloader entries for Xen, see this page for an example.
Dom0 support in Linux
The Linux kernel packaged with the distribution should be compiled with Xen support, see this page. Booting the machine with Xen and the default kernel should complete successfully.
init scripts: xencommons
Xen relies on an init script called xencommons to initialize all the services. It should be executed by default at boot time.
qemu-xen-traditional and qemu-xen
The two device model binaries Xen relies on should be installed in the location where Xl expect them to be, that by default is /usr/lib/xen/bin, and can be changed modifying tools/libxl/_libxl_paths.h.
Xen udev scripts
The Xen udev scripts should be installed correctly: after manually creating the default bridge named xenbr0, starting a guest with a vif, the vif should be added to the bridge automatically.
LINUX DISTRIBUTION: SUGGESTED CONFIGURATIONS
Setting up lvm is strongly suggested: storing raw disk images in lvm volumes is the fasted possible configuration as you can exploit the in-kernel disk backend (CONFIG_XEN_BLKDEV_BACKEND).