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From: Eric McRae <eric@tera.com>
Newsgroups: comp.unix.bsd.freebsd.misc,comp.unix.bsd.freebsd.misc
Subject: Need help with VME memory access
Date: Thu, 03 Jul 1997 10:34:38 -0700
Organization: Tera Computer Company
Lines: 61
Message-ID: <33BBE2AE.167EB0E7@tera.com>
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Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:43931
I'm running RTMX (variation on OpenBSD) on an MVME162 with a 32 Mbyte
VME RAM card.
Using 162-Bug, I set the VME Master #1 start address to 0x40000000 and
end to 0x41ffffff. I can read/write the entire VME RAM using a tiny
loop assembled using 162-Bug.
The following tiny application however, produces a segmentation fault
due to an attempt read from the VME RAM virtual address:
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/mman.h>
typedef unsigned long u32;
int
main( int argc, char **argv )
{
char buf[8192];
volatile u32 *vmeP;
int resultN;
int fd = open("/dev/vmel0", O_RDWR, 0);
if( fd == -1 )
perror("Open Failed");
vmeP = (u32 *)mmap( 0, 0x2000, PROT_READ|PROT_WRITE,
MAP_FILE, fd, 0xc0000000 );
if( vmeP == (u32 *)-1 )
perror("mmap Failed");
else
{
printf("VME starts at %x\n", (u32)vmeP);
printf("Contents = %x\n", *vmeP);
}
}
Running this program results in the following output on the tty
VME starts at 400d000
Bus error (core dumped)
And the following output is produced on the console (Thanks to a printf
left in vmelmmap()):
vmel c0000000 pa 40000000
vmel c0001000 pa 40001000
vmel c0000000 pa 40000000
vmelmmap actually returns 0xc0000000 >> 12 or 0xc0000. I don't know why
mmap() is returning 0x400d000 or if that matters.
Can anyone tell me what I'm doing wrong?
--
Eric McRae, Electro-Logic Machines, Inc. eric@elmi.com (consultant to:)
Tera Computer Company 2815 Eastlake Ave E., Seattle WA, 98102
eric@tera.com, Phone: 206.325.0800x479, FAX: 206.325.2433