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Date:      Thu, 5 Sep 2002 16:49:57 -0400 (EDT)
From:      Andrew Gallatin <gallatin@cs.duke.edu>
To:        ticso@cicely.de
Cc:        John Baldwin <jhb@FreeBSD.ORG>, freebsd-alpha@FreeBSD.ORG
Subject:   Re: ithread preemption
Message-ID:  <15735.50037.249179.284948@grasshopper.cs.duke.edu>
In-Reply-To: <20020905204558.GF13050@cicely9.cicely.de>
References:  <15735.44660.835003.901974@grasshopper.cs.duke.edu> <XFMail.20020905153533.jhb@FreeBSD.org> <15735.47204.905352.900631@grasshopper.cs.duke.edu> <20020905201443.GD13050@cicely9.cicely.de> <15735.48281.30915.800894@grasshopper.cs.duke.edu> <20020905204558.GF13050@cicely9.cicely.de>

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Bernd Walter writes:
 > On Thu, Sep 05, 2002 at 04:20:41PM -0400, Andrew Gallatin wrote:
 > > 
 > > Bernd Walter writes:
 > >  > OK - I have some basic understandig problems here.
 > >  > 
 > >  > Why should ithreads ever return to PAL?
 > > 
 > > Because PAL initiates the interrupt and creates a stackframe on the
 > > interrupted thread's kernel stack.  It then calls the OSes interrupt
 > > vector.  In order to restore the state of the world to be like it was
 > > before the interrupt happened, we need to return back to pal.
 > 
 > That's clear, but this is not the ithread.
 > ithreads never return - see ithread_loop() in kern_intr.c.
 > 

I think we were being sloppy with our language.  The code which
schedules the ithread is what returns back to PAL.

Drew

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