1 /*
2 * This file and its contents are supplied under the terms of the
3 * Common Development and Distribution License ("CDDL"), version 1.0.
4 * You may only use this file in accordance with the terms of version
5 * 1.0 of the CDDL.
6 *
7 * A full copy of the text of the CDDL should have accompanied this
8 * source. A copy of the CDDL is also available via the Internet at
9 * http://www.illumos.org/license/CDDL.
10 */
11
12 /*
13 * Copyright 2015 Toomas Soome <tsoome@me.com>
14 */
15
16 /*
17 * Chain loader to load BIOS boot block either from MBR or PBR.
18 *
19 * Note the boot block location 0000:7c000 conflicts with loader, so we need to
20 * read in to temporary space and relocate on exec, when btx is stopped.
21 */
22
23 #include <sys/cdefs.h>
24 #include <stand.h>
25 #include <sys/param.h>
26 #include <sys/linker.h>
27 #include <sys/diskmbr.h>
28
29 #include "bootstrap.h"
30 #include "libi386/vbe.h"
31 #include "libi386/libi386.h"
32 #include "btxv86.h"
33
34 /*
35 * The MBR/VBR is located in first sector of disk/partition.
36 * Read 512B to temporary location and set up relocation. Then
37 * exec relocator.
38 */
39 #define SECTOR_SIZE (512)
40
41 COMMAND_SET(chain, "chain", "chain load boot block from device", command_chain);
42
43 static int
command_chain(int argc,char * argv[])44 command_chain(int argc, char *argv[])
45 {
46 int fd, len, size = SECTOR_SIZE;
47 struct stat st;
48 vm_offset_t mem = 0x100000;
49 struct i386_devdesc *rootdev;
50
51 if (argc == 1) {
52 command_errmsg = "no device or file name specified";
53 return (CMD_ERROR);
54 }
55 if (argc != 2) {
56 command_errmsg = "invalid trailing arguments";
57 return (CMD_ERROR);
58 }
59
60 fd = open(argv[1], O_RDONLY);
61 if (fd == -1) {
62 command_errmsg = "open failed";
63 return (CMD_ERROR);
64 }
65
66 len = strlen(argv[1]);
67 if (argv[1][len-1] != ':') {
68 if (fstat(fd, &st) == -1) {
69 command_errmsg = "stat failed";
70 close(fd);
71 return (CMD_ERROR);
72 }
73 if (size != st.st_size) {
74 command_errmsg = "invalid size";
75 return (CMD_ERROR);
76 }
77 } else if (strncmp(argv[1], "disk", 4) != 0) {
78 command_errmsg = "can only use disk device";
79 close(fd);
80 return (CMD_ERROR);
81 }
82
83 i386_getdev((void **)(&rootdev), argv[1], NULL);
84 if (rootdev == NULL) {
85 command_errmsg = "can't determine root device";
86 close(fd);
87 return (CMD_ERROR);
88 }
89
90 if (archsw.arch_readin(fd, mem, size) != size) {
91 command_errmsg = "failed to read disk";
92 close(fd);
93 return (CMD_ERROR);
94 }
95 close(fd);
96
97 /* File or device, we assume MBR or VBR boot code */
98 if (*((uint16_t *)PTOV(mem + DOSMAGICOFFSET)) != DOSMAGIC) {
99 command_errmsg = "wrong magic";
100 return (CMD_ERROR);
101 }
102
103 bios_set_text_mode(3);
104 relocater_data[0].src = mem;
105 relocater_data[0].dest = 0x7C00;
106 relocater_data[0].size = size;
107
108 relocator_edx = bd_unit2bios(rootdev);
109 relocator_esi = relocater_size;
110 relocator_ds = 0;
111 relocator_es = 0;
112 relocator_fs = 0;
113 relocator_gs = 0;
114 relocator_ss = 0;
115 relocator_cs = 0;
116 relocator_sp = 0x7C00;
117 relocator_ip = 0x7C00;
118 relocator_a20_enabled = 0;
119
120 i386_copyin(relocater, 0x600, relocater_size);
121
122 dev_cleanup();
123
124 __exec((void *)0x600);
125
126 panic("exec returned");
127 return (CMD_ERROR); /* not reached */
128 }
129