is it possible to check the register info change before and after one system call for one thread?

[Guanghui, Cheng]

Hello:
	i want to know whether to know the register info changes before and after one 
system call for one thread.
	Especially, the l4_thread_ex_regs could change the pc of one thread. I want 
to know the status of other registers after this system call.
	is it possible to use jdb to get this?
	Thanks.
							Cheng Guanghui