Re: [Xen-devel] The use of evtchn_upcall_mask

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.09.12 at 04:50, Yaogun Wen <techno.geek.0x01@xxxxxxxxx> wrote:
>> Setting an event channel pending isn't tied to the channel being
>> unmasked - in particular, for polled event channels, one would
>> keep them masked permanently, yet still expect events to be
>> signaled. The mask really controls whether an upcall is actually
>> permitted (just like EFLAGS.IF controls whether interrupts can
>> be injected).
> This explanation helps me to understand the meaning of VCPUINFO_upcall_mask.
> I don't know x86 assembly language, but according to your explanation,
> it seems that guest which only have masked channel will still receive
> the events.
> But from the comment of vcpu_info struct, it says "The mask
> (evtchn_upcall_mask) is read before making an event upcall to the
> guest".
> So, which one is correct?

Both. If I'm understanding correctly, you're mixing up per-channel
masks (evtchn_mask[]) and the global delivery mask
(evtchn_upcall_mask). If that's not the case, I'm afraid I don't
follow what your concern is.

Jan


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