Linux

 
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <pthread.h>
#include <linux/types.h>
int main()
{
       int fd;
       char data[20];
       __u8 *start_addr,*end_addr;
       int PageSize;
       if ( (PageSize = sysconf(_SC_PAGE_SIZE)) < 0) {
           perror("sysconf() Error=");
                   return -1;
       }
       printf("PageSize = %d\n",PageSize);
       if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1)
       {
               printf("Error opening /dev/mem\n");
               return -1;
       }
       start_addr = mmap(0, PageSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
                                                                               0);
       if(start_addr == MAP_FAILED)
       {
               printf("enc_status map failed %s\n", strerror(errno));
               return -1;
       }
       end_addr = start_addr + (4096 - 1);
       strcpy(data, "Test Msg");
       printf("\n%s:Writing NVRAM.......\n", __FUNCTION__);
       if(write(fd, data, strlen(data)) <= 0)
       {
               printf("%s: Not able to write on NVRAM. %s.\n", __FUNCTION__,
                               strerror(errno));
               return -1;
       }
       printf("\n%s:Synching NVRAM.......\n", __FUNCTION__);
       if(msync(start_addr, PageSize, MS_SYNC) < 0)
       {
               printf("%s: Not able to sync to NVRAM. %s.\n", __FUNCTION__,
                               strerror(errno));
               return -1;
       }
       printf("\n%s:reading NVRAM.......\n", __FUNCTION__);
       strcpy(data, "");
       if(read(fd, data, sizeof(data)) <= 0)
       {
               printf("%s: Not able to read on NVRAM. %s.\n", __FUNCTION__,
                               strerror(errno));
               return -1;
       }
       printf("%s: data  %s.\n", __FUNCTION__, data);
       return 0;
}