shared memory??

[john]

I'm trying to use shared memory to access a frame buffer and it
doesn't seem to work. I am running 2.2L.  I put the appropriate
shmcreate lines in /etc/rc.d/shm.rc but when my program runs
nothing seems to happen (I check for error returns and from
shmat and shmget but no error indication is given).  to check it out
I tried the tiny programbelow to try and write some high intensity
"A"'s to the herc. mono adapter.  The program runs in a couple of seconds
but nothing changes on the screens.  The only thing I have noticed is
that in  system5.nm  shmat() is listed as an int rather than a char *

Any hints/suggestions are welcome; thanks!
john

 ...!ubc-vision!fornax!bby-bc!john


program below compiled by  cc -Ml prog.c

main (argc,argv)
int argc;
char **argv;
{
extern char *shmat();
int shmid=shmget(0xb0000,32768,0);
char *shmaddr = shmat(shmid,(char *)0);

unsigned int i;
for (i=0; i<32000; i++) {*shmaddr++ = 65; *shmaddr++ = 15;};
}