ex_regs system call is forzed in the do_ipc process

Guanghui, Cheng cheng.guanghui.ml at gmail.com
Thu Oct 22 15:26:13 CEST 2009

 > 	If i ajust the exception handler when the L4 thread is runnning in the
> > L4 thread but i try to trigger the exception ipc when the main thread is
> > running in the L4eRTL thread, the ex_regs system call can't return and it
> > seems it will be blocked in the kernel whatever i used
> > "L4_THREAD_EX_REGS_NO_CANCEL" or not. Vice versa.
> I don't quite get a clear understanding of what's happening from the
> description but maybe a thread is busy looping. Is some thread ready?
	Now the L4eRTL with using exception ipc triggerred  interrupt-handling 
could work.  All the demos before i prepared in the RTLWS11 about l4ertl
could work with this version, about : single l4ertl thread in single doman,
double l4ertl threads in single domain, multiple l4ertl domains coexisting
with l4linux. But obviously the booting l4linux is much slower when runnng
 l4ertl app comparing to last l4ertl version (lazy interrupt handling in 
	In this place i describe the problem again and hope it could be useful 
for you.
	You know the L4eRTl could support multiple l4ertl threads in one 
l4 thread. But firstly there is one l4 thread responsible for some necessary 
initialization issues such as init_sched, init_time and init_signals which are 
necessary for l4ertl system.  And then l4 thread will create a first l4ertl 
main thread which will execute the user space main function. And this l4 
thread will run as the idle thread in the l4ertl system finally.
	If there is a context switch between l4ertl thread to l4ertl idle (l4 thread) 
the ex_regs_flags system call will be frozed.
	Later i fixed the ugly design and now there is l4ertl idle thread is 
also a l4ertl thread not l4 thread any more. The system could work. I
reserved all the environments and codes which could cause this frozen.
Maybe next time i could show you and you could debug it.
	The next step should be the implementation of vtimers. Because
it is in the user space and i could try different timer source like RTC and 
HPET. Last time you mentioned HPET and i think it should be better than 
RTC because HPET is internal timer and it should be faster than external RTC
timer. Right?
								Cheng Guanghui
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