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From: mannemel@handel.cs.colostate.edu (devakumar mannemela)
Newsgroups: comp.os.minix
Subject: Compaction in Minix  ( Novice Question)
Message-ID: <11362@ccncsu.ColoState.EDU>
Date: 24 Nov 90 10:07:33 GMT
Sender: news@ccncsu.ColoState.EDU
Reply-To: mannemel@handel.cs.colostate.edu (devakumar mannemela)
Organization: Colorado State University
Lines: 95


Hi !


	I am working on a project on MINIX ( for my OS course).I am 
implementing memory compaction.( don't tell me it is   not very useful
in PC environment. 8-)  . the purpose of the project is to get ourself
thoroughly familiar with one of the main parts of the OS , in which 
i think we are succeeding).

	I wrote a routine 'do_comp' which does the actual compaction
and included it as a part of alloc.c in the mm.My original idea
is to create a system call "compact" which actually calls ' do_comp'
and write a user program which runs 'compact' every x seconds , in the
back ground. ( and start this user program in /etc/rc  like /etc/update)

	Coming to my problem , I created a system call which
calls the do-compaction routine (present in my memory manager). So i
added  relevant definitions to h/callnr.h and the tables of fs and
memory manager.I wrote a library routine compact and tried to append it
to libc.a. The actual routine is

compact.c------

main()
{
	return callm1(MM,CMPACT,0,0,0,NIL_PTR,NIL_PTR,NIL_PTR);
}

and i compiled it to get compact.s
		( cc -c -Di8088 -LIB compact.c )


now i tried to add it to libc.a , in the following manner.

ar rb uniqport.s libc.a compact.s

  				( puts libc.a before uniqport.s , which is
				  the first thing in the archived lib)
Now compact.s is the first thing in libc.a  .

I verified that compact.s is actually added to libc.a byb typing 
ar t libc.a.

Now i wrote a small program comp.c and tried compiling it.

----------------------comp.c---------------------

main()
{
	sleep(120);
	while(1)
	{
		compact();
		sleep(10);
	}
}

--------------------------------------------------------
cc comp.c
------------------

 	unresolved references
	-compact
--------------------

That was the result. Isn't it supposed to recognise compact by checking in 
libc.a ? 

Are there any other places i have to indicate the addition of the new system 
call "compact" ?

Are there any other ways of running my 'do_comp' routine  in the background
every x seconds , other than by creating a system call ? ( i tried using
fork in the main of mm. Doesn't seem to work. )

BTW , I am working on a 80286 based PC-AT , with minix itself as the
development system.

I am completely struck up here. No idea how to procede.

Any help would be very much appreciated.

Thanks

Bye,
Deva Kumar M.

P.S. :  Does the whole thing makes sense ?
  	
	E-mail preferred.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
     Dev Kumar M.			E-mail :mannemel@handel.cs.colostate.edu
  Colorado State University             Tel    : 303 - 484 - 7970
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++