Path: utzoo!utgpu!watserv1!watdragon!himacdonald
From: himacdonald@watdragon.waterloo.edu (Hamish Macdonald)
Newsgroups: comp.sys.amiga.tech
Subject: Re: resource tracking
Message-ID: <21183@watdragon.waterloo.edu>
Date: 22 Feb 90 22:16:45 GMT
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In-reply-to: deven@rpi.edu's message of 22 Feb 90 19:11:10 GMT


>>>>> On 22 Feb 90 19:11:10 GMT, deven@rpi.edu (Deven T. Corzine) said:

Deven> On 22 Feb 90 02:09:34 GMT, peter@sugar.hackercorp.com (Peter da
Deven> Silva) said:

Peter> Look, the point isn't what a system call is or is not. The
Peter> point is that apart from the single special case of writing to
Peter> the screen, every I/O (including reading from the mouse or
Peter> keyboard) involves messages. And the screen output stuff also
Peter> involves massive amounts of shared data.

Deven> Consider.  A system call does not HAVE to be I/O.  Yes, all I/O
Deven> to Exec devices and AmigaDOS filesystems involves message
Deven> passing.  Not all _system_ calls do.  Does AddTask() use
Deven> messages?  No.  Don't try telling me it's not a system call.

Question: Does I/O to Exec devices HAVE to involve message passing?

I don't believe so.  When I do a 'who' on the Amiga here, it tells me
that I have an 'input.device' task running, and a couple of
'trackdisk.device' tasks running, and a number of others.  Nowhere do
I see a 'serial.device' task (or anything remotely interpretable as
such) running.  Since I am talking through VLT at the moment, I am
sure that the serial.device Exec device is in use.

I believe that access to the serial.device can be made in the context
of the process (or task) accessing it, and no messages need be sent
to/from a special serial.device process.

Comments?

Hamish.
--
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watmath!watdragon!himacdonald     himacdonald@watdragon.waterloo.edu
"Guns seldom solve any problems; they merely decide whose will shall
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