From mboxrd@z Thu Jan  1 00:00:00 1970
From: jmk@plan9.bell-labs.com
To: 9fans@cse.psu.edu
Subject: Re: [9fans] drawterm and linux 2.4.4 SMP
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Date: Fri, 20 Jul 2001 22:38:30 -0400
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On Fri Jul 20 21:16:24 EDT 2001, crdevilb@mtu.edu wrote:
> I remember there was talk on the list some time ago about drawterm for
> linux and how it may very well be broken under linux 2.4; well, that
> time is here.  It seems (to me) that it is broken because I was just
> stepping through the source (because it was SEGVing), and the macro CT
> (at linux.c:30) seems to nondeterministically alternate between giving
> the right answer and giving NULL, because linux.c:/^gettss(void)
> nondeterministically alternates between returning 6 and 8...
>
> Was there some suggestion or patch anybody had to fix this, or am I
> going to be digging into the linux kernel to find yet another hack to
> solve this?
>
> Thanks in advance for any help.
>
> --
> Colin DeVilbiss
> crdevilb@mtu.edu

I haven't looked at that code but from the description it looks like
the thread switch hack Phil Winterbottom and I did when we ported Inferno
to Linux a very long time ago. At that time Linux used the task
switch capabililty of the x86 (why, I don't know) so it was possible
to use the contents of the task-switch register as an index to find the process
context in the shared memory as there was no other private per-process
memory available (Plan 9 at least gives each process a private stack).

You will need to find some other way to do it, but it will probably be
just as much of a hack. I don't know what possibilities there are under
Linux 2.4, but they must surely have added something (that could be used).
Perhaps someone who is more familiar with both the thread-switching
scheme used in drawterm and Linux can give a better answer.