Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!cs.dal.ca!aucs!852026d
From: 852026d@aucs.uucp (DAWD)
Newsgroups: comp.os.xinu
Subject: Stack allocation in PCXINU !!!
Message-ID: <1990Mar6.183151.13848@aucs.uucp>
Date: 6 Mar 90 18:31:51 GMT
Reply-To: 852026d@aucs.UUCP (DAWD)
Organization: School of Computer Science, Acadia Univ., Nova Scotia
Lines: 21


    It is mentioned in Comer/Fossum's book ,XINU P.C edition, that
PCXINU allocates a stack area for each process, in a way that if more 
than one process starts, their stacks are allocated CONTIGUOUSLY upward.

I found out that PCXINU does not allocate processes' stacks CONTIGUOUSLY,
because when PCXINU creates a process it uses function getmem() to allocate 
it's stack , and function getmem() simply returns the first free block of
memory from the free list. The following code will show it clearly  : -


      ...
      resume(creat(process#2,......));
      userblock = getmem(100);
      resume(creat(process#2,......));
      ....
   

Please post any comments .

  Thank You