Re: utility to backup BIOS in Linux

[Ronald G Minnich]

this saves the last MEG of 32-bit address space to stdout.

#include <stdio.h>
#include <fcntl.h>

#include <unistd.h>
#include <sys/mman.h>

main(int argc, char *argv[])
{
  int i;
  volatile unsigned char *cp;
  int fd;
  volatile void *v;
  off_t nvram = 0xfff00000;
  /* avoid linux mmap bug */
  size_t length = 0x100000 /*- 0x1000*/;
  if (argc > 1)
    nvram = (strtol(argv[1], 0, 0)) << 16;
  if (argc > 2)
    length = (strtol(argv[2], 0, 0)) ;
    if((fd = open("/dev/mem",O_RDWR)) != -1)
    {
      v = mmap(0, length, PROT_READ | PROT_WRITE, MAP_SHARED,fd,nvram);
      fprintf(stderr, "mmap returns %p\n", v);

      if ( (int)v == -1)
      {
        perror("mmap");
        exit(1);
      }
    } else {
      perror("open /dev/mem");
      exit(1);
    }
  write(1, v, length);
}