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From: trevc@tecate.mips.com (Trevor Cotton)
Newsgroups: comp.sys.mips
Subject: Re: mmap
Message-ID: <4210@spim.mips.COM>
Date: 3 Jun 91 16:47:15 GMT
References: <1991Jun3.151307.20857@watdragon.waterloo.edu>
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In article <1991Jun3.151307.20857@watdragon.waterloo.edu>, drclark@daisy.waterloo.edu (David R. Clark) writes:
|> The following program (actually a slight variation of it) works on one of
|> our local systems (Sequent).  On an M2000 running 4.51 the call to mmap fails
|> (invalid arguments).  Any ideas?  What I really want to do is choose an arbitrary
|> region of memory that does not overlap the current program or data space and then
|> map data into the region.  Until I get the simple version working though, I am stuck.
|> 
|> #include <sys/mman.h>
|> #include <sys/types.h>
|> #include <fcntl.h>
|> main() {
|> 
|> 	int f;
|> 	int t;
|> 	char *s;
|> 
|> 	f = open("AND",O_RDWR,0);
|> 
|> 	if (f == -1) perror("open");
|> 
|> 	s = malloc(getpagesize());
|> 	if (mmap(s,getpagesize(),PROT_READ|PROT_WRITE,MAP_SHARED,f,0) == -1)
|> 		perror("mmap");
|> 	printf("%s",s);
|> }

RISC/os 4.5x supports only a subset of the mmap and munmap system calls.
Only mapping of character devices is allowed, and only one device can
be mapped by a process. 
What is "AND" in your example?

RISC/os 5.0 will add memory mapped file functionality that operates in
accordance with SVR4 semantics.

We hope to start beta testing of RISC/os 5.0 around the end of July.

-- 
--trevc--

  Trevor Cotton, Sustaining Engineering, MIPS Computer Systems Inc.
  MS 6-05, 930 DeGuigne Drive, Sunnyvale, CA 94088-3650
  Tel: +1 408 524 7286  Fax: +1 408 524 7521
  Email: {wyse,ames,decwrl,pyramid}!mips!trevc    trevc@mips.com