I've tried using regular etchnhalf kernels to boot PXE instead of the usual 2.6.18 + unionfs kernel that FAI uses. Using any kernel the nfsroot simply does not mount and I presume it's due to unionsfs module which is not available or loaded (if available by default with 2.6.24-etchnhalf).
Any clues on how to boot with regular or even backport kernels ? Thnx! Vincent Fortier Informatique