From mboxrd@z Thu Jan  1 00:00:00 1970
From: lm@mcvoy.com (Larry McVoy)
Date: Sun, 15 Jan 2017 19:15:10 -0800
Subject: [TUHS] Article on 'not meant to understand this'
In-Reply-To: <20170116014444.GA32261@minnie.tuhs.org>
References: <20170116014444.GA32261@minnie.tuhs.org>
Message-ID: <20170116031510.GB6647@mcvoy.com>

Yeah, saw it.  I'm of the opinion that you aren't really truly an OS
person unless you've written a context switcher.  I wrote one for a
user level threading package I did for Udi Manber as a grad student.
I did most of the work in C and then dropped to assembler for the
trampoline.

It's really not that complicated, I think people make it out to be
a bigger deal than it is.  You're saving state (registers), switching
stacks, and changing the return address so you return in the new 
process.

Well, not that complicated on a simple machine line a VAX or a 68K
or a PDP11.  I sort of stopped playing in assembler when super scalar
out of order stuff came around and I couldn't get the mental picture 
of what was where.

On Mon, Jan 16, 2017 at 11:44:44AM +1000, Warren Toomey wrote:
> http://thenewstack.io/not-expected-understand-explainer/
> 
> in case you haven't seen it yet.
> 
> Cheers, Warren

-- 
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Larry McVoy            	     lm at mcvoy.com             http://www.mcvoy.com/lm