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From: dhb@rayssd.UUCP
Newsgroups: net.unix-wizards
Subject: File system limit in 4.2 BSD (followup)
Message-ID: <714@rayssd.UUCP>
Date: Mon, 29-Apr-85 09:15:12 EDT
Article-I.D.: rayssd.714
Posted: Mon Apr 29 09:15:12 1985
Date-Received: Wed, 1-May-85 02:22:14 EDT
Distribution: net
Organization: Raytheon Co., Portsmouth RI
Lines: 24

Thanks to all who replied to my request for a way to mount more than
fifteen file systems in 4.2 BSD.  There is indeed something besides
the size of the fields in the core map that needs to be changed and
it CAN cause weird swapping problems or other random behaviour.  In
locore.s there is a routine called "Fastreclaim" which "knows" about
the core map structure.  What it knows is the size of the structure
and the location of two one-bit fields within it.  Therefore if you
make any changes to this structure you have to change the code in
locore.s.  One suggestion that was made was to make the size of the
structure and the offsets to these fields #defines in the cmap.h file.
I hope that the people at Berkeley take this suggestion and put it in
the next release.  What I did to solve the problem was to increase
the size of the "mdev" field in the core map structure and move the
field that followed it to the end of the structure.  This way the offsets
to the two other fields remained constant and I only had to change one
line in locore.s.  If you want to know the specific changes that I made,
send me mail and I will send you a diff listing.  If I get enough
requests I will post it to the net.
-- 
	Dave Brierley
	Raytheon Co.; Portsmouth RI; (401)-847-8000 x4073
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