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Re: [Xen-devel] Clock Interrupt not occurring. hypervisor_callback not b

To: "Ivan Kelly" <ivanbkelly@xxxxxxxxx>
Subject: Re: [Xen-devel] Clock Interrupt not occurring. hypervisor_callback not being called. (more info)
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Wed, 1 Mar 2006 22:42:44 +0000
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On 1 Mar 2006, at 16:17, Ivan Kelly wrote:

The problem seems to be that evtchn_pending[0] is not being updated
fast enough after the callback is made. Therefore the callback is
running and seeing nothing as pending and discarding anything that
happens.

This is certainly not happening or I think it would have been discovered and fixed by now. :-)

When firing an event the pending flag gets set first, then the selector bit, then the evtchn_upcall_pending master flag, then the upcall happens.

When processing an upcall, you should clear bits in the opposite order.

 -- Keir


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