summaryrefslogtreecommitdiffstats
path: root/arch/i386/boot/tools/build.c
blob: 6835f6d47c31e8f5913a670c6bd7bdd57f1e7b7c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 1997 Martin Mares
 */

/*
 * This file builds a disk-image from three different files:
 *
 * - bootsect: compatibility mbr which prints an error message if
 *             someone tries to boot the kernel directly.
 * - setup: 8086 machine code, sets up system parm
 * - system: 80386 code for actual system
 *
 * It does some checking that all files are of the correct type, and
 * just writes the result to stdout, removing headers and padding to
 * the right amount. It also writes some system data to stderr.
 */

/*
 * Changes by tytso to allow root device specification
 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
 * Cross compiling fixes by Gertjan van Wingerde, July 1996
 * Rewritten by Martin Mares, April 1997
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <unistd.h>
#include <fcntl.h>
#include <asm/boot.h>

typedef unsigned char byte;
typedef unsigned short word;
typedef unsigned long u32;

#define DEFAULT_MAJOR_ROOT 0
#define DEFAULT_MINOR_ROOT 0

/* Minimal number of setup sectors (see also bootsect.S) */
#define SETUP_SECTS 4

byte buf[1024];
int fd;
int is_big_kernel;

void die(const char * str, ...)
{
	va_list args;
	va_start(args, str);
	vfprintf(stderr, str, args);
	fputc('\n', stderr);
	exit(1);
}

void file_open(const char *name)
{
	if ((fd = open(name, O_RDONLY, 0)) < 0)
		die("Unable to open `%s': %m", name);
}

void usage(void)
{
	die("Usage: build [-b] bootsect setup system [rootdev] [> image]");
}

int main(int argc, char ** argv)
{
	unsigned int i, sz, setup_sectors;
	int c;
	u32 sys_size;
	byte major_root, minor_root;
	struct stat sb;

	if (argc > 2 && !strcmp(argv[1], "-b"))
	  {
	    is_big_kernel = 1;
	    argc--, argv++;
	  }
	if ((argc < 4) || (argc > 5))
		usage();
	if (argc > 4) {
		if (!strcmp(argv[4], "CURRENT")) {
			if (stat("/", &sb)) {
				perror("/");
				die("Couldn't stat /");
			}
			major_root = major(sb.st_dev);
			minor_root = minor(sb.st_dev);
		} else if (strcmp(argv[4], "FLOPPY")) {
			if (stat(argv[4], &sb)) {
				perror(argv[4]);
				die("Couldn't stat root device.");
			}
			major_root = major(sb.st_rdev);
			minor_root = minor(sb.st_rdev);
		} else {
			major_root = 0;
			minor_root = 0;
		}
	} else {
		major_root = DEFAULT_MAJOR_ROOT;
		minor_root = DEFAULT_MINOR_ROOT;
	}
	fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);

	file_open(argv[1]);
	i = read(fd, buf, sizeof(buf));
	fprintf(stderr,"Boot sector %d bytes.\n",i);
	if (i != 512)
		die("Boot block must be exactly 512 bytes");
	if (buf[510] != 0x55 || buf[511] != 0xaa)
		die("Boot block hasn't got boot flag (0xAA55)");
	buf[508] = minor_root;
	buf[509] = major_root;
	if (write(1, buf, 512) != 512)
		die("Write call failed");
	close (fd);

	file_open(argv[2]);				    /* Copy the setup code */
	for (i=0 ; (c=read(fd, buf, sizeof(buf)))>0 ; i+=c )
		if (write(1, buf, c) != c)
			die("Write call failed");
	if (c != 0)
		die("read-error on `setup'");
	close (fd);

	setup_sectors = (i + 511) / 512;	/* Pad unused space with zeros */
	/* for compatibility with ancient versions of LILO. */
	if (setup_sectors < SETUP_SECTS)
		setup_sectors = SETUP_SECTS;
	fprintf(stderr, "Setup is %d bytes.\n", i);
	memset(buf, 0, sizeof(buf));
	while (i < setup_sectors * 512) {
		c = setup_sectors * 512 - i;
		if (c > sizeof(buf))
			c = sizeof(buf);
		if (write(1, buf, c) != c)
			die("Write call failed");
		i += c;
	}

	file_open(argv[3]);
	if (fstat (fd, &sb))
		die("Unable to stat `%s': %m", argv[3]);
	sz = sb.st_size;
	fprintf (stderr, "System is %d kB\n", sz/1024);
	sys_size = (sz + 15) / 16;
	if (!is_big_kernel && sys_size > DEF_SYSSIZE)
		die("System is too big. Try using bzImage or modules.");
	while (sz > 0) {
		int l, n;

		l = (sz > sizeof(buf)) ? sizeof(buf) : sz;
		if ((n=read(fd, buf, l)) != l) {
			if (n < 0)
				die("Error reading %s: %m", argv[3]);
			else
				die("%s: Unexpected EOF", argv[3]);
		}
		if (write(1, buf, l) != l)
			die("Write failed");
		sz -= l;
	}
	close(fd);

	if (lseek(1, 497, SEEK_SET) != 497)		    /* Write sizes to the bootsector */
		die("Output: seek failed");
	buf[0] = setup_sectors;
	if (write(1, buf, 1) != 1)
		die("Write of setup sector count failed");
	if (lseek(1, 500, SEEK_SET) != 500)
		die("Output: seek failed");
	buf[0] = (sys_size & 0xff);
	buf[1] = ((sys_size >> 8) & 0xff);
	if (write(1, buf, 2) != 2)
		die("Write of image length failed");

	return 0;					    /* Everything is OK */
}