PREEMPT_RT patched linux boot up problem

Hello,

I92%ve been using buildroot kernel on a AT91RM9200 board and it has been
working well. Recently I applied kernel PREEMPT_RT patch to get better
interrupt latency and rebuilt the kernel. The kernel halted at the
very end of the booting up process:

85%85.
Looking up port of RPC 100003/2 on 192.168.0.80
Looking up port of RPC 100005/1 on 192.168.0.80
VFS: Mounted root (nfs filesystem) on device 0:11.
Freeing init memory: 92K

I used statically linked 93%hello world94% application to replace /sbin/
init and it was not called. Anyone got the RT patch working on any
other AT91 controllers? Does it need other patches? Any help is
greatly appreciated.

--yhu