problems with shared memory

Adam Wozniak awozniak at
Thu Mar 7 03:53:43 EST 2002

I've got Linux 2.4.16 running on a custom MPC8260 board.

when I do the program below in a tight loop

while true
./foo 8675 1024

Things pop after about 20 iterations.  It'll choose a different spot
in the kernel to pop depending on what options I've compiled into the
kernel.  I believe I've got some memory corruption going on.  When I
poke around with a hardware debugger I see values in kernel structures
which clearly aren't right.

Any known problems with shared memory in the 2.4.16 kernel on the MPC8260?

This should be easy enough for someone to try to reproduce.

=== begin foo.c
#include <stdio.h>
#include <sys/types.h>
#include <sys/shm.h>

int main (int argc, char **argv)
   int j;
   char *q;
   int p;

   p = shmget(atoi(argv[1]),  atoi(argv[2]), IPC_CREAT | 0666);

   q = shmat(p, NULL, 0);

   printf("at @ %p \n", q);

      int i;
      for (i = 0; i < atoi(argv[2]); i++)

=== end foo.c

Adam Wozniak (KG6GZR)   COM DEV Broadband - Digital and Software Systems
awozniak at      805 Aerovista Place, San Luis Obispo, CA 93401
                        Voice: (805) 544-1089       Fax: (805) 544-2055

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