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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.unix-wizards
Subject: Re: File system limit in 4.2 BSD
Message-ID: <4522@umcp-cs.UUCP>
Date: Wed, 3-Apr-85 18:05:11 EST
Article-I.D.: umcp-cs.4522
Posted: Wed Apr  3 18:05:11 1985
Date-Received: Sat, 6-Apr-85 02:14:48 EST
References: <681@rayssd.UUCP> <2089@sun.uucp>
Distribution: net
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 42
Keywords: cmap, Fastreclaim

I strongly urge all 4.2 VARs to do something about this.  BRL (and UCB
and others) have modified h/cmap.h to contain #defines for use by
locore.s.  This at least centralizes the information.  (By the way, I
have a sneaking suspicion that Fastreclaim was done as a quick hack by
the Franz group.  Anyone "in the know" care to comment?)

[Excerpts from the BRL version of h/cmap.h:]
/*
 * core map entry
 *
 * Limits imposed by this structure:
 *
 *		limit		     cur. size		fields
 *	Physical memory+		64 Mb	c_next, c_prev, c_hlink
 *	Mounted filesystems		255	c_mdev
 *	size of a process segment	1 Gb	c_page
 *	filesystem size			2 Gb	c_blkno
 *	proc, text table size		1024	c_ndx
 *
 *	+ memory can be expanded by converting first three entries
 *	to bit fields, shrinking c_unused, and increasing MAXMEM below.
 */
#ifndef	LOCORE
struct cmap
{
	[...]
};
#else	LOCORE
/*
 * bit offsets of elements in cmap
 */
#define	C_INTRANS	66
#define	C_FREE		67
#define	SZ_CMAP		16		/* sizeof(struct cmap) */

#define	MAXMEM		64*1024		/* maximum memory, in Kbytes */
#endif	LOCORE
[...]
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 4251)
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris@maryland