File: /usr/src/linux/arch/i386/boot/tools/build.c
1 /*
2 * $Id: build.c,v 1.5 1997/05/19 12:29:58 mj Exp $
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * Copyright (C) 1997 Martin Mares
6 */
7
8 /*
9 * This file builds a disk-image from three different files:
10 *
11 * - bootsect: exactly 512 bytes of 8086 machine code, loads the rest
12 * - setup: 8086 machine code, sets up system parm
13 * - system: 80386 code for actual system
14 *
15 * It does some checking that all files are of the correct type, and
16 * just writes the result to stdout, removing headers and padding to
17 * the right amount. It also writes some system data to stderr.
18 */
19
20 /*
21 * Changes by tytso to allow root device specification
22 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
23 * Cross compiling fixes by Gertjan van Wingerde, July 1996
24 * Rewritten by Martin Mares, April 1997
25 */
26
27 #include <stdio.h>
28 #include <string.h>
29 #include <stdlib.h>
30 #include <stdarg.h>
31 #include <sys/types.h>
32 #include <sys/stat.h>
33 #include <sys/sysmacros.h>
34 #include <unistd.h>
35 #include <fcntl.h>
36 #include <asm/boot.h>
37
38 typedef unsigned char byte;
39 typedef unsigned short word;
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 (see also bootsect.S) */
46 #define SETUP_SECTS 4
47
48 byte buf[1024];
49 int fd;
50 int is_big_kernel;
51
52 void die(const char * str, ...)
53 {
54 va_list args;
55 va_start(args, str);
56 vfprintf(stderr, str, args);
57 fputc('\n', stderr);
58 exit(1);
59 }
60
61 void file_open(const char *name)
62 {
63 if ((fd = open(name, O_RDONLY, 0)) < 0)
64 die("Unable to open `%s': %m", name);
65 }
66
67 void usage(void)
68 {
69 die("Usage: build [-b] bootsect setup system [rootdev] [> image]");
70 }
71
72 int main(int argc, char ** argv)
73 {
74 unsigned int i, c, sz, setup_sectors;
75 u32 sys_size;
76 byte major_root, minor_root;
77 struct stat sb;
78
79 if (argc > 2 && !strcmp(argv[1], "-b"))
80 {
81 is_big_kernel = 1;
82 argc--, argv++;
83 }
84 if ((argc < 4) || (argc > 5))
85 usage();
86 if (argc > 4) {
87 if (!strcmp(argv[4], "CURRENT")) {
88 if (stat("/", &sb)) {
89 perror("/");
90 die("Couldn't stat /");
91 }
92 major_root = major(sb.st_dev);
93 minor_root = minor(sb.st_dev);
94 } else if (strcmp(argv[4], "FLOPPY")) {
95 if (stat(argv[4], &sb)) {
96 perror(argv[4]);
97 die("Couldn't stat root device.");
98 }
99 major_root = major(sb.st_rdev);
100 minor_root = minor(sb.st_rdev);
101 } else {
102 major_root = 0;
103 minor_root = 0;
104 }
105 } else {
106 major_root = DEFAULT_MAJOR_ROOT;
107 minor_root = DEFAULT_MINOR_ROOT;
108 }
109 fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
110
111 file_open(argv[1]);
112 i = read(fd, buf, sizeof(buf));
113 fprintf(stderr,"Boot sector %d bytes.\n",i);
114 if (i != 512)
115 die("Boot block must be exactly 512 bytes");
116 if (buf[510] != 0x55 || buf[511] != 0xaa)
117 die("Boot block hasn't got boot flag (0xAA55)");
118 buf[508] = minor_root;
119 buf[509] = major_root;
120 if (write(1, buf, 512) != 512)
121 die("Write call failed");
122 close (fd);
123
124 file_open(argv[2]); /* Copy the setup code */
125 for (i=0 ; (c=read(fd, buf, sizeof(buf)))>0 ; i+=c )
126 if (write(1, buf, c) != c)
127 die("Write call failed");
128 if (c != 0)
129 die("read-error on `setup'");
130 close (fd);
131
132 setup_sectors = (i + 511) / 512; /* Pad unused space with zeros */
133 /* for compatibility with ancient versions of LILO. */
134 if (setup_sectors < SETUP_SECTS)
135 setup_sectors = SETUP_SECTS;
136 fprintf(stderr, "Setup is %d bytes.\n", i);
137 memset(buf, 0, sizeof(buf));
138 while (i < setup_sectors * 512) {
139 c = setup_sectors * 512 - i;
140 if (c > sizeof(buf))
141 c = sizeof(buf);
142 if (write(1, buf, c) != c)
143 die("Write call failed");
144 i += c;
145 }
146
147 file_open(argv[3]);
148 if (fstat (fd, &sb))
149 die("Unable to stat `%s': %m", argv[3]);
150 sz = sb.st_size;
151 fprintf (stderr, "System is %d kB\n", sz/1024);
152 sys_size = (sz + 15) / 16;
153 /* 0x28000*16 = 2.5 MB, conservative estimate for the current maximum */
154 if (sys_size > (is_big_kernel ? 0x28000 : DEF_SYSSIZE))
155 die("System is too big. Try using %smodules.",
156 is_big_kernel ? "" : "bzImage or ");
157 if (sys_size > 0xefff)
158 fprintf(stderr,"warning: kernel is too big for standalone boot "
159 "from floppy\n");
160 while (sz > 0) {
161 int l, n;
162
163 l = (sz > sizeof(buf)) ? sizeof(buf) : sz;
164 if ((n=read(fd, buf, l)) != l) {
165 if (n < 0)
166 die("Error reading %s: %m", argv[3]);
167 else
168 die("%s: Unexpected EOF", argv[3]);
169 }
170 if (write(1, buf, l) != l)
171 die("Write failed");
172 sz -= l;
173 }
174 close(fd);
175
176 if (lseek(1, 497, SEEK_SET) != 497) /* Write sizes to the bootsector */
177 die("Output: seek failed");
178 buf[0] = setup_sectors;
179 if (write(1, buf, 1) != 1)
180 die("Write of setup sector count failed");
181 if (lseek(1, 500, SEEK_SET) != 500)
182 die("Output: seek failed");
183 buf[0] = (sys_size & 0xff);
184 buf[1] = ((sys_size >> 8) & 0xff);
185 if (write(1, buf, 2) != 2)
186 die("Write of image length failed");
187
188 return 0; /* Everything is OK */
189 }
190