About the exception ipc reply

Guanghui, Cheng cheng.guanghui.ml at gmail.com
Fri Oct 16 12:43:50 CEST 2009


On Friday 16 October 2009 17:05:27 Adam Lackorzynski wrote:
> Hi Cheng,
>
> On Thu Oct 15, 2009 at 13:57:32 +0800, Guanghui, Cheng wrote:
> > 	BUT. I have a problem about my code when i fixing the stack of main
> > thread. The correct code which could work well is like this:
> > utcb = l4_utcb_get();
> > eip = utcb->exc.eip;
> > esp = utcb->exc.esp;
> > utcb->values[12] = (l4_umword_t)(do_irq);
> > esp_loc = 1024 - (esp - (l4_umword_t)stack)/4;
> > stack[esp_loc - 1] = eip;
> > l4_msgtag ...
> > l4_ipc_send_tag
> > 	In the code above i only reset the next stack with return address (old
> > eip). But it seems i can't reset the new stack pointer like
> > utcb->values[15] = esp - 4
> > 	In my opinion it should do  but if i did it can't work. It seems some
> > tricky here. Can you tell me why it is like this?
> > 	Additinally, i tried this way about handling interrupt  with interrupt
> > number like this:
> > 	void do_irq(int irq)
> > 	it can't work either.
>
> Please refer to the attached modified version of your program. It's a
> bit more tricky than that, regs also need to be saved etc...
	Your code is so smart. I tried to use the assembler
 code to finish the process. But ret instruction could 
only be back to the last step. iret is a really good idea
 to go back  the origin place like goto.
	Thanks a lot.
						Cheng Guanghui
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