What versions of the host kernel and UML?

host is 2.6.20-16-generic , the raw one from feisty fawn
uml is 2.6.20.3-ubuntu1 , the same built from the ubuntu kernel sources

Otherwise the printk in the module doesn't work in the uml whereas it works in the host and otherwise printk works well (I tried for instance the log command with uml_mconsole). Perhaps because of the version magic (I'm fixing this) and my force (modprobe -f) to load the module ?