From: utzoo!decvax!harpo!seismo!hao!hplabs!sri-unix!obrien@Rand-Unix
Newsgroups: net.unix-wizards
Title: Re: 4.1 kernel questions
Article-I.D.: sri-arpa.908
Posted: Fri Apr  1 21:29:00 1983
Received: Tue Apr 19 05:55:30 1983

Sounds like you have to add some info about processes.

	The notion of a PCB is built into the VAX hardware so UNIX has to
use it.  The first entry in the "u" structure is a plain vanilla PCB.
The context switch stuff is actually buried in "locore.s" (at least the
nitty-gritty part) where load-process-context and store-process-context
instructions can be executed.  Of course there's other stuff in "main.c"
and probably "machdep.c" as well as "clock.c" and other places having
to do with the UNIX mechanics of process switching as well as scheduling.

	Where you would go about adding something depends on whether or
not you need the information while the process is swapped out.  If you
do, it has to go into the "proc" structure (defined in "proc.h").  If
you only need it when the process is in-core (viz. the PCB) then the "u"
structure is preferable.