1 // SPDX-License-Identifier: GPL-2.0
2 /* This utility makes a bootblock suitable for the SRM console/miniloader */
5 * mkbb <device> <lxboot>
7 * Where <device> is the name of the device to install the bootblock on,
8 * and <lxboot> is the name of a bootblock to merge in. This bootblock
9 * contains the offset and size of the bootloader. It must be exactly
18 /* Minimal definition of disklabel, so we don't have to include
19 * asm/disklabel.h (confuses make)
22 #define MAXPARTITIONS 8 /* max. # of partitions */
26 #define u8 unsigned char
30 #define u16 unsigned short
34 #define u32 unsigned int
38 u32 d_magic; /* must be DISKLABELMAGIC */
39 u16 d_type, d_subtype;
51 u16 d_rpm, d_interleave, d_trackskew, d_cylskew;
52 u32 d_headswitch, d_trkseek, d_flags;
55 u32 d_magic2; /* must be DISKLABELMAGIC */
58 u32 d_bbsize, d_sbsize;
66 } d_partitions[MAXPARTITIONS];
70 typedef union __bootblock {
73 struct disklabel __label;
76 unsigned long __pad2[63];
77 unsigned long __checksum;
79 char bootblock_bytes[512];
80 unsigned long bootblock_quadwords[64];
83 #define bootblock_label __u1.__label
84 #define bootblock_checksum __u2.__checksum
86 int main(int argc, char ** argv)
88 bootblock bootblock_from_disk;
89 bootblock bootloader_image;
94 /* Make sure of the arg count */
96 fprintf(stderr, "Usage: %s device lxboot\n", argv[0]);
100 /* First, open the device and make sure it's accessible */
101 dev = open(argv[1], O_RDWR);
107 /* Now open the lxboot and make sure it's reasonable */
108 fd = open(argv[2], O_RDONLY);
115 /* Read in the lxboot */
116 nread = read(fd, &bootloader_image, sizeof(bootblock));
117 if(nread != sizeof(bootblock)) {
118 perror("lxboot read");
119 fprintf(stderr, "expected %zd, got %d\n", sizeof(bootblock), nread);
123 /* Read in the bootblock from disk. */
124 nread = read(dev, &bootblock_from_disk, sizeof(bootblock));
125 if(nread != sizeof(bootblock)) {
126 perror("bootblock read");
127 fprintf(stderr, "expected %zd, got %d\n", sizeof(bootblock), nread);
131 /* Swap the bootblock's disklabel into the bootloader */
132 bootloader_image.bootblock_label = bootblock_from_disk.bootblock_label;
134 /* Calculate the bootblock checksum */
135 bootloader_image.bootblock_checksum = 0;
136 for(i = 0; i < 63; i++) {
137 bootloader_image.bootblock_checksum +=
138 bootloader_image.bootblock_quadwords[i];
141 /* Write the whole thing out! */
142 lseek(dev, 0L, SEEK_SET);
143 if(write(dev, &bootloader_image, sizeof(bootblock)) != sizeof(bootblock)) {
144 perror("bootblock write");