No Subject

[Zhixu Liu <liuzx@bessun.ihep.ac.cn>]

Hi, everyone:

I have a question about the share memory use mmap. (in rtlinux-2.2)
I use the example in mmap, but what i want to know is is there is a 
limit of the size of share memory, for when i try to map a region
about 1000 int, in the kernel module the computer always dead.

Following is the program i use.

===================================
#include <rtl.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>

//DATA * start;
int *start;
size_t length = 1000;
#define BASE_ADDRESS (96*0x100000) 
	//96Mb I have reserve the left 32Mb in lilo.conf

int init_module(void )
{
	int i;

	int fd = open("/dev/mem", O_RDWR);
	if (fd < 0) {
		rtl_printf("failed to open /dev/mem\n");
		return -1;
	}
	start = (int *)mmap(0,length*sizeof(int),PROT_READ|PROT_WRITE,
			MAP_SHARED,fd,BASE_ADDRESS);
	if (start == (int *) -1) {
		rtl_printf("failed to map /dev/mem\n");
		return -1;
	}
	rtl_printf("%p\n",start);
	for (i = 0; i < 1000; i++) {
		rtl_printf ("%d\t",i);
		start[i]=i;
		rtl_printf ("%d\n", start[i]);
		}
	return 0;
}

void cleanup_module(void )
{
       munmap(start, length);
}

#ifndef MODULE 

int main(void)
{
	if (init_module() == 0) {
		cleanup_module();
	}
	return 0;
}
#endif
===========================

If i run this program in module, then the computer is dead.
If i run in user program, it's ok.

Anyone have some some suggestion about this?

Thanks in anvance.

Zhixu Liu