1 /*
2 * Makes a tree bootable image for IBM Evaluation boards.
3 * Basically, just take a zImage, skip the ELF header, and stuff
4 * a 32 byte header on the front.
5 *
6 * We use htonl, which is a network macro, to make sure we're doing
7 * The Right Thing on an LE machine. It's non-obvious, but it should
8 * work on anything BSD'ish.
9 */
10
11 #include <fcntl.h>
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <string.h>
15 #include <sys/stat.h>
16 #include <unistd.h>
17 #include <netinet/in.h>
18 #ifdef __sun__
19 #include <inttypes.h>
20 #else
21 #include <stdint.h>
22 #endif
23
24 /* This gets tacked on the front of the image. There are also a few
25 * bytes allocated after the _start label used by the boot rom (see
26 * head.S for details).
27 */
28 typedef struct boot_block {
29 uint32_t bb_magic; /* 0x0052504F */
30 uint32_t bb_dest; /* Target address of the image */
31 uint32_t bb_num_512blocks; /* Size, rounded-up, in 512 byte blks */
32 uint32_t bb_debug_flag; /* Run debugger or image after load */
33 uint32_t bb_entry_point; /* The image address to start */
34 uint32_t bb_checksum; /* 32 bit checksum including header */
35 uint32_t reserved[2];
36 } boot_block_t;
37
38 #define IMGBLK 512
39 unsigned int tmpbuf[IMGBLK / sizeof(unsigned int)];
40
main(int argc,char * argv[])41 int main(int argc, char *argv[])
42 {
43 int in_fd, out_fd;
44 int nblks, i;
45 unsigned int cksum, *cp;
46 struct stat st;
47 boot_block_t bt;
48
49 if (argc < 5) {
50 fprintf(stderr, "usage: %s <zImage-file> <boot-image> <load address> <entry point>\n",argv[0]);
51 exit(1);
52 }
53
54 if (stat(argv[1], &st) < 0) {
55 perror("stat");
56 exit(2);
57 }
58
59 nblks = (st.st_size + IMGBLK) / IMGBLK;
60
61 bt.bb_magic = htonl(0x0052504F);
62
63 /* If we have the optional entry point parameter, use it */
64 bt.bb_dest = htonl(strtoul(argv[3], NULL, 0));
65 bt.bb_entry_point = htonl(strtoul(argv[4], NULL, 0));
66
67 /* We know these from the linker command.
68 * ...and then move it up into memory a little more so the
69 * relocation can happen.
70 */
71 bt.bb_num_512blocks = htonl(nblks);
72 bt.bb_debug_flag = 0;
73
74 bt.bb_checksum = 0;
75
76 /* To be neat and tidy :-).
77 */
78 bt.reserved[0] = 0;
79 bt.reserved[1] = 0;
80
81 if ((in_fd = open(argv[1], O_RDONLY)) < 0) {
82 perror("zImage open");
83 exit(3);
84 }
85
86 if ((out_fd = open(argv[2], (O_RDWR | O_CREAT | O_TRUNC), 0666)) < 0) {
87 perror("bootfile open");
88 exit(3);
89 }
90
91 cksum = 0;
92 cp = (void *)&bt;
93 for (i = 0; i < sizeof(bt) / sizeof(unsigned int); i++)
94 cksum += *cp++;
95
96 /* Assume zImage is an ELF file, and skip the 64K header.
97 */
98 if (read(in_fd, tmpbuf, sizeof(tmpbuf)) != sizeof(tmpbuf)) {
99 fprintf(stderr, "%s is too small to be an ELF image\n",
100 argv[1]);
101 exit(4);
102 }
103
104 if (tmpbuf[0] != htonl(0x7f454c46)) {
105 fprintf(stderr, "%s is not an ELF image\n", argv[1]);
106 exit(4);
107 }
108
109 if (lseek(in_fd, (64 * 1024), SEEK_SET) < 0) {
110 fprintf(stderr, "%s failed to seek in ELF image\n", argv[1]);
111 exit(4);
112 }
113
114 nblks -= (64 * 1024) / IMGBLK;
115
116 /* And away we go......
117 */
118 if (write(out_fd, &bt, sizeof(bt)) != sizeof(bt)) {
119 perror("boot-image write");
120 exit(5);
121 }
122
123 while (nblks-- > 0) {
124 if (read(in_fd, tmpbuf, sizeof(tmpbuf)) < 0) {
125 perror("zImage read");
126 exit(5);
127 }
128 cp = tmpbuf;
129 for (i = 0; i < sizeof(tmpbuf) / sizeof(unsigned int); i++)
130 cksum += *cp++;
131 if (write(out_fd, tmpbuf, sizeof(tmpbuf)) != sizeof(tmpbuf)) {
132 perror("boot-image write");
133 exit(5);
134 }
135 }
136
137 /* rewrite the header with the computed checksum.
138 */
139 bt.bb_checksum = htonl(cksum);
140 if (lseek(out_fd, 0, SEEK_SET) < 0) {
141 perror("rewrite seek");
142 exit(1);
143 }
144 if (write(out_fd, &bt, sizeof(bt)) != sizeof(bt)) {
145 perror("boot-image rewrite");
146 exit(1);
147 }
148
149 exit(0);
150 }
151