I thought I'd kick off my Citrix blog with a question I get pretty often from Linux enthusiasts: how to install unsupported Linux distributions on XenServer 4.1.
The most common solution people find is to use the "Other Install Media" template, insert the distribution installation CD, and find that the mouse cursor doesn't work when they boot into X11. The reason for this is that they are using the hardware-assisted emulation mode of installing Linux. In this mode (dubbed "HVM"), all input and output is emulated, and in particular the mouse interface uses the USB tablet interface. If the distribution doesn't include a driver for USB tablets, then no mouse will appear.
Windows guests run at high-speed in HVM mode due to the installation of the XenServer tools which install high-speed drivers, but these are not necessary for Linux distributions since they can be run in para-virtualized mode (dubbed "PV"). This involves obtaining a Xen-enabled PV kernel from the distribution, and modifying the VM record in XenServer to boot into this kernel instead of HVM mode. The XenServer built-in templates for popular distributions such as RHEL, CentOS or SUSE Linux already automate all this and are in PV mode from the installer onwards.