On Thu, Jan 20, 2005 at 08:52:00PM +0100, Manuel Bouyer wrote:
> Hi,
> Again I'm stuck with some assembly code (I don't know much about i386 assembly,
> and I've never mixed assembly and C). I have this code in xen/i386/vector.S:
> #define hypervisor_asm_unmask(num)                      \
>         movl    irq_to_evtchn + (num) * 4,%ecx          ;\
> 	movl    HYPERVISOR_shared_info,%eax             ;\
> 	lock                                            ;\
> 	btrl    %ecx,EVENTS_MASK(%eax)
> (BTW, what does the "lock" instruction ?)
> I need to add a call to this C function at the end of this asm
> statement:
> 	pirq_notify(num)
> num being a constant. The prototype for the function is:
> void pirq_notify(int irq);
> 
> I tried
> 	        pushl   $(num)                                  ;\
> 		call    _C_LABEL(pirq_notify) 
> but I get a page fault trap at the first call, with something that doesn't
> make much sense on the stack. So I guess I missed something, but I don't
> know what ... I assume registers are callee-saved, but maybe I'm wrong
> on this.

I've not been able to figure out how to call pirq_notify, however I've
been able to inline the needed hypercall here. Now I need to figure out
how to test a bit in a int32_t array, and avoid the hypercall when not
needed ...

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 26 ans d'experience feront toujours la difference
--