On upgrade from 2.2.8 to 3.2 I could no longer find any refernece to
BOUNCE_BUFFERS

#	To: arch@_ERASE_freebsd.org
#	cc: jhs@
#	Subject: src/sys/i386/i386/machdep.c if (MAXMEM/4 < Maxmem) Maxmem = MAXMEM/4;
#	
#	In src/sys/i386/i386/machdep.c
#	
#	1.1.5 code was
#		#ifdef MAXMEM
#		if (MAXMEM/4 < Maxmem)
#		Maxmem = MAXMEM/4;
#		#endif
#	2.current code is:
#		Maxmem = MAXMEM/4;
#	1.1.5 seems safer though !
#	
#	If we asert 
#		options "MAXMEM=16384"
#	& then borrow the kernel to run on an 8M system,
#	wont this now screw up badly ?
#	
#	I offer this patch:
#	--------
#	*** old/src/sys/i386/i386/machdep.c     Tue Nov 15 19:09:00 1994
#	--- new/src/sys/i386/i386/machdep.c     Mon Nov 21 02:38:03 1994
#	***************
#	*** 287,292 ****
#	--- 287,296 ----
#	  #ifdef BOUNCE_BUFFERS
#	  	/*
#	  	 * If there is more than 16MB of memory, allocate some bounce buffers
#	+ 	 * (because ISA bus with just 24 address bits prevents addresses
#	+ 	 * above 16M being used to access either ISA cards such as disc
#	+ 	 * controllers, (or even EISA disc controllers running in ISA
#	+ 	 * compatibility mode)).
#	  	 */
#	  	if (Maxmem > 4096) {
#	  		if (bouncepages == 0)
#	***************
#	*** 1307,1313 ****
#	  	Maxmem = pagesinext + 0x100000/PAGE_SIZE;
#	  
#	  #ifdef MAXMEM
#	! 	Maxmem = MAXMEM/4;
#	  #endif
#	  	/*
#	  	 * Calculate number of physical pages, but account for Maxmem
#	--- 1311,1338 ----
#	  	Maxmem = pagesinext + 0x100000/PAGE_SIZE;
#	  
#	  #ifdef MAXMEM
#	! 	/* In /sys/i386/conf/GENERIC, using
#	! 	 *   	options "MAXMEM=16384"
#	! 	 * gets kernel here to use just first 16M,
#	! 	 * (useful for such as when testing ISA systems where one 
#	! 	 * suspects the 16 to 32M area of RAM is not cached 
#	! 	 * (eg Gigagbyte ISA-486 Taiwan motherboard owned by
#	! 	 * jhs@.
#	! 	 */
#	! #define K_PER_PAGE    ( PAGE_SIZE / 1024 )
#	! 	if ( Maxmem > ( MAXMEM / K_PER_PAGE ) )
#	! 		{
#	! 		printf("%s %d to %d pages of %d bytes,\n(%ld %s %ld).\n",
#	! 			"Reducing memory from",
#	! 			Maxmem,
#	! 			MAXMEM / K_PER_PAGE,
#	! 			PAGE_SIZE,
#	! 			(long)Maxmem * (PAGE_SIZE),
#	! 			"reducing to",
#	! 			((long)(MAXMEM/K_PER_PAGE )) * (PAGE_SIZE)
#	! 			);
#	! 		Maxmem = MAXMEM / K_PER_PAGE;
#	! 		}
#	  #endif
#	  	/*
#	  	 * Calculate number of physical pages, but account for Maxmem
#	--------
#	
#	PS It seems there's rather too many manifest constants such 4096, 4, 1024,
#	floating around in machdep.c, hence K_PER_PAGE.
#	
#	Julian Stacey <jhs@