Hi Folks,
Can anybody help us in the following problem:
(still working on embeddedXEN with ARM core)
we''re trying to use miniOS (basically the same than x86 version) and we
face a strange issue regarding
the hypervisor callback. Here is a portion of code:
...
#define active_evtchns(cpu,sh,idx) \
((sh)->evtchn_pending[idx] & \
~(sh)->evtchn_mask[idx])
...
l1 = xchg(&vcpu_info->evtchn_pending_sel, 0);
while (l1 != 0) {
l1i = __ffs(l1);
l1 &= ~(1 << l1i);
while ((l2 = active_evtchns(cpu, s, l1i)) != 0) {
l2i = __ffs(l2);
l2 &= ~(1 << l2i);
port = (l1i << 5) + l2i;
do_event(port, regs);
}
}
The timer init function bind the VIRQ_TIMER to a specific handler, ok.
VIRQ_TIMER is equal to 0 and therefore, the bit 0 of
evtchn_pending and evtchn_mask are set correctly (checked). However, the code
above tells us that l1i is set to 1 (and not 0).
Consequently, we never statisfy the second while() condition.
It seems that there is a shift of one bit in the computation of l1i, since _ffs
return 1 for the least significant bit (and not 0).
What do you think?
What I''m wondering is how it could work .. (and probably it could ;-)
just something that probably I missed....
Thanks for your help
Daniel
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