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rdsinit(1)		    General Commands Manual		    rdsinit(1)

       rdsinit - RDS heap initialization utility

       rdsinit log data_seg

       rdsinit log data_seg datalen saddr hlen slen nl chunk

       rdsinit -f log data_seg datalen saddr hlen slen nl chunk

       rdsinit	is a utility that constructs an	initialized RDS	heap in	an RVM
       segment.	 It is intended	to create a structure that can	be  loaded  by

       There are three different ways of using rdsinit.	 General users are ex-
       pected to use first two interactive modes, where	users may  supply  pa-
       rameters	 for  the rds heap interactively or on command line arguments.
       However,	in both	cases, users will be asked  interactively  to  confirm
       their choice of parameters before rdsinit goes ahead to make any	perma-
       nent change.  These are the preferred modes of using  rdsinit.	Script
       writers,	 however,  may prefer to supply	all the	parameters on the com-
       mand line and no	confirmation required for those	parameters.   This  is
       accomodate in the third mode where an additional	switch of -f (firm) is
       supplied	on the command line.

       In any case, two	command-line parameters	are always required:  log  and
       data_seg.   The former is the name of the RVM log, which	must have pre-
       viously been initialized	by rvmutl; the latter is the name of the  data
       segment	that will be initialized with an RDS heap.  If either is miss-
       ing, a command line error is printed.  If the log has not been initial-
       ized,  an  RVM  error will result.  A short message indicating RVM ini-
       tialization succeeded is	then printed.  Both the	log and	 data  segment
       can be regular files or raw partitions.

       After the name of log and data segment, there are six other numeric pa-
       rameters	required.  They	are summarized here and	will be	explained  one
       by one in the following paragraphs:

	      Length of	data segment

       saddr  Starting address of rvm

       hlen   Heap region length

       slen   Static region length

       nl     Number of	lists of free block

       chunk  Chunk size

       While  entering these six numeric parameters, either on command line on
       via the interactive prompt, users may use numeric number	 in  hexadeci-
       mal, decimal or even octal notation.  Hexadecimal numbers are preceeded
       by Ox, decimal numbers are preceeded by nothing and octal  numbers  are
       preceded	by 0.

       Special	note for long time rdsinit user: the old rdsinit automatically
       assumed saddr, hlen and slen parameters supplied	on command  lines  are
       in  hexidecimal	and  did not require the prefix	0x.  This is no	longer
       true with this version of rdsinit.

       Users specify the  length  of  the  data	 segment  with	the  parameter
       datalen.	  Again, old version of	rdsinit	did not	require	this parameter
       if the data segment was a regular file and it existed  already  at  the
       time  of	 running  rdsinit.  This special case is eliminated: length of
       data segment must to be supplied	in all circumstances.

       Starting	address	of rvm,	or saddr, is where heap	and static region will
       be  mapped  into	 virtual  memory.  Heap	region is located right	at the
       starting	address, while static region is	located	 at  starting  address
       plus heap region	length.	 Users may need	to have	some knowledges	of the
       overall layout of the virtual memory use	by the system before they  can
       make  the  right	choice of starting address.  For example, the starting
       address of rvm must be much larger  than	 the  largest  possible	 break
       point  of your application, and it should not be	in conflict other uses
       of virtual memory (such as use by shared	libraries).  It	must  also  be
       on  a  page boundary.  In CMU, we use 0x20000000	(536870912) with Linux
       and BSD44, or 0x70000000	(1879048192) with Mach.	  It  is  possible  to
       choose other values, but	you have to choose them	carefully.

       Length  of  regions  of	heap and static	are specified by the parameter
       hlen and	slen respectively.  They both must be integral multiple	of pa-
       gesize  of  the	system.	  Also,	the combined length of the two regions
       must be smaller than the	length of data segment minus one extra page.

       Note that the above three parameters: saddr, hlen, slen,	are permanent.
       They  can't be changed without re-initizing (and	brain-wiping) the data

       The next	two parameters:	nl and chunk are related to underlying	struc-
       ture of management of the heap.	RDS uses the Quick Fit method for heap
       allocation.  In this method, free blocks	are maintained by a number  of
       free lists, each	list for one particular	size of	free blocks.  Specifi-
       cally, there will be nl free lists, and each of	them  will  have  free
       blocks of size chunk respectively.

       Chunk size must be integral multiple of sizeof(char *), and be at least
       RDS_MIN_CHUNK_SIZE.    Number   of   lists    must    be	   at	 least
       RDS_MIN_FREE_LISTS.	 For  example,	a reasonable choice is to have
       100 free	list with chunk	size 32	bytes.

       Once all	the parameters are chosen, rdsinit will	ask user for confirma-
       tion before it goes ahead and make permanent change on the log and data
       segment.	 Note in the following example that those numerical  arguments
       are presented in	both hexidecimal and decimal (in bracket).  It is safe
       to quit at this point and no permanent changes will be made.

       The following parameters	are chosen:
	  length of data segment:    0xf5000 (	 1003520)
	 starting address of rvm: 0x20000000 ( 536870912)
			heap len:    0xf0000 (	  983040)
		      static len:     0x4000 (	   16384)
			  nlists:	0x64 (	     100)
		      chunk size:	0x20 (	      32)
       Do you agree with these parameters ? (y|n|q) y

       If user supplied	the -f (firm) switch on	command	line, this  last  con-
       firmation will not show up.

       rds_init_heap (3), rds_load_heap	(3), rds_zap_heap (3), rvm_create_seg-
       ment (3), rvm_load_segment (3), rvmutl (1)

       David C.	Steere,	created	man page

       Yui W. Lee, modified (Sept 1997)



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