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Re: [Xen-devel] fooey. no interrupts.

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] fooey. no interrupts.
From: ron minnich <rminnich@xxxxxxxx>
Date: Tue, 10 Aug 2004 09:46:45 -0600 (MDT)
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it looks like I'm falling into the gap between how linux does interrupts 
and how Plan 9 does them. 

I'm still seeing the race condition, even with the suggestions you posted
in place in my interrupt handler. I'll try to work this a bit more but it
does seem to me that if you're taking too long in your interrupt handler
you will get bit by the race -- Xen will I assume pre-empt dom1 in the
event of a clock interrupt, and at that point it is game over. I think
long term a "level interrupt" construct may be needed, but that is
conjecture on my part.

Trying to latch levels in a UP is a lot different than latching them in
hardware, since the hardware is more or less running all the time, but the
Xen/Dom0/Dom1 is all time shared. Looking at the race sequence I think I'm
seeing I'm still not convinced it is completely avoidable, but I will hope
I am wrong.

thanks for the good suggestions!


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