[Fedora-xen] xennet is missing

Hello , I am using xen 3.03 redhat rpm on RHEL 5 tikanga. Now i am trying to boot Fedora 12 as DomU using paravirtualization. I installed F12 using the virt manager. Its booting fine but network is not working. Its giving error like: # Bringing up interface eth0: xennet device eth0 does not seem to be present, delaying initialization. After googling i came to know that xennet and xenblk drivers are missing. So how can i now build xennet into the F12 DomU kernel. The xennet and xenblk drivers are missing . What should i do next? Any guidance. Thanks Vipul