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	Tue, 10 Jun 1997 13:43:53 -0500 (EST)
From: "John S. Dyson" <toor@dyson.iquest.net>
Message-Id: <199706101843.NAA00476@dyson.iquest.net>
Subject: Re: rfork() man page wrong?
In-Reply-To: <3395AF81.4487EB71@whistle.com> from Julian Elischer at "Jun 4, 97 11:10:09 am"
To: julian@whistle.com (Julian Elischer)
Date: Tue, 10 Jun 1997 13:43:53 -0500 (EST)
Cc: current@freebsd.org, dyson@freebsd.org
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> I've checked the man page and the sources..
> 
> it appears to me that the following section of the man page
> is wrong..
> john, if you are reading, can you check if this is what 
> you understand?
>
I am reading now (sorry for the delay :-)).

> 
> -------
> RFMEM     If set, the kernel will force sharing of the entire ad-
>           dress space.  The child will then inherit all the shared
>           segments the parent process owns. Other segment types
>           will be unaffected.  Subsequent forks by the parent will
>           then propagate the shared data and bss between children.
>           The stack segment is always split.  May be set only with
>           RFPROC.
> --------
> 
The docs for RFMEM are wrong.  The kernel will cause total address
space sharing, which makes the threads fairly light weight.  I am
about to make some changes for SMP/kernel based threads to allow
for per-cpu data though (but that is in kernel mode only where you
see the difference.)  You have to manage the stack issues, and
I have some example and working code if you want it.  (I am using
it, and have delivered it for others to use.)  I plan to refine
the code before committing it, but I'll give you (or anyone) the
code if anyone wants it.

John