arch/x86/boot/tools/build.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *  Copyright (C) 1997 Martin Mares
   4  *  Copyright (C) 2007 H. Peter Anvin
   5  */
   6
   7 /*
   8  * This file builds a disk-image from two different files:
   9  *
  10  * - setup: 8086 machine code, sets up system parm
  11  * - system: 80386 code for actual system
  12  *
  13  * It does some checking that all files are of the correct type, and
  14  * just writes the result to stdout, removing headers and padding to
  15  * the right amount. It also writes some system data to stderr.
  16  */
  17
  18 /*
  19  * Changes by tytso to allow root device specification
  20  * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
  21  * Cross compiling fixes by Gertjan van Wingerde, July 1996
  22  * Rewritten by Martin Mares, April 1997
  23  * Substantially overhauled by H. Peter Anvin, April 2007
  24  */
  25
  26 #include <stdio.h>
  27 #include <string.h>
  28 #include <stdlib.h>
  29 #include <stdarg.h>
  30 #include <sys/types.h>
  31 #include <sys/stat.h>
  32 #include <sys/sysmacros.h>
  33 #include <unistd.h>
  34 #include <fcntl.h>
  35 #include <sys/mman.h>
  36 #include <asm/boot.h>
  37
  38 typedef unsigned char  u8;
  39 typedef unsigned short u16;
  40 typedef unsigned long  u32;
  41
  42 #define DEFAULT_MAJOR_ROOT 0
  43 #define DEFAULT_MINOR_ROOT 0
  44
  45 /* Minimal number of setup sectors */
  46 #define SETUP_SECT_MIN 5
  47 #define SETUP_SECT_MAX 64
  48
  49 /* This must be large enough to hold the entire setup */
  50 u8 buf[SETUP_SECT_MAX*512];
  51 int is_big_kernel;
  52
  53 static void die(const char * str, ...)
  54 {
  55         va_list args;
  56         va_start(args, str);
  57         vfprintf(stderr, str, args);
  58         fputc('\n', stderr);
  59         exit(1);
  60 }
  61
  62 static void usage(void)
  63 {
  64         die("Usage: build [-b] setup system [rootdev] [> image]");
  65 }
  66
  67 int main(int argc, char ** argv)
  68 {
  69         unsigned int i, sz, setup_sectors;
  70         int c;
  71         u32 sys_size;
  72         u8 major_root, minor_root;
  73         struct stat sb;
  74         FILE *file;
  75         int fd;
  76         void *kernel;
  77
  78         if (argc > 2 && !strcmp(argv[1], "-b"))
  79           {
  80             is_big_kernel = 1;
  81             argc--, argv++;
  82           }
  83         if ((argc < 3) || (argc > 4))
  84                 usage();
  85         if (argc > 3) {
  86                 if (!strcmp(argv[3], "CURRENT")) {
  87                         if (stat("/", &sb)) {
  88                                 perror("/");
  89                                 die("Couldn't stat /");
  90                         }
  91                         major_root = major(sb.st_dev);
  92                         minor_root = minor(sb.st_dev);
  93                 } else if (strcmp(argv[3], "FLOPPY")) {
  94                         if (stat(argv[3], &sb)) {
  95                                 perror(argv[3]);
  96                                 die("Couldn't stat root device.");
  97                         }
  98                         major_root = major(sb.st_rdev);
  99                         minor_root = minor(sb.st_rdev);
 100                 } else {
 101                         major_root = 0;
 102                         minor_root = 0;
 103                 }
 104         } else {
 105                 major_root = DEFAULT_MAJOR_ROOT;
 106                 minor_root = DEFAULT_MINOR_ROOT;
 107         }
 108         fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
 109
 110         /* Copy the setup code */
 111         file = fopen(argv[1], "r");
 112         if (!file)
 113                 die("Unable to open `%s': %m", argv[1]);
 114         c = fread(buf, 1, sizeof(buf), file);
 115         if (ferror(file))
 116                 die("read-error on `setup'");
 117         if (c < 1024)
 118                 die("The setup must be at least 1024 bytes");
 119         if (buf[510] != 0x55 || buf[511] != 0xaa)
 120                 die("Boot block hasn't got boot flag (0xAA55)");
 121         fclose(file);
 122
 123         /* Pad unused space with zeros */
 124         setup_sectors = (c + 511) / 512;
 125         if (setup_sectors < SETUP_SECT_MIN)
 126                 setup_sectors = SETUP_SECT_MIN;
 127         i = setup_sectors*512;
 128         memset(buf+c, 0, i-c);
 129
 130         /* Set the default root device */
 131         buf[508] = minor_root;
 132         buf[509] = major_root;
 133
 134         fprintf(stderr, "Setup is %d bytes (padded to %d bytes).\n", c, i);
 135
 136         /* Open and stat the kernel file */
 137         fd = open(argv[2], O_RDONLY);
 138         if (fd < 0)
 139                 die("Unable to open `%s': %m", argv[2]);
 140         if (fstat(fd, &sb))
 141                 die("Unable to stat `%s': %m", argv[2]);
 142         sz = sb.st_size;
 143         fprintf (stderr, "System is %d kB\n", (sz+1023)/1024);
 144         kernel = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0);
 145         if (kernel == MAP_FAILED)
 146                 die("Unable to mmap '%s': %m", argv[2]);
 147         sys_size = (sz + 15) / 16;
 148         if (!is_big_kernel && sys_size > DEF_SYSSIZE)
 149                 die("System is too big. Try using bzImage or modules.");
 150
 151         /* Patch the setup code with the appropriate size parameters */
 152         buf[0x1f1] = setup_sectors-1;
 153         buf[0x1f4] = sys_size;
 154         buf[0x1f5] = sys_size >> 8;
 155         buf[0x1f6] = sys_size >> 16;
 156         buf[0x1f7] = sys_size >> 24;
 157
 158         if (fwrite(buf, 1, i, stdout) != i)
 159                 die("Writing setup failed");
 160
 161         /* Copy the kernel code */
 162         if (fwrite(kernel, 1, sz, stdout) != sz)
 163                 die("Writing kernel failed");
 164         close(fd);
 165
 166         /* Everything is OK */
 167         return 0;
 168 }