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/libi386.h"
31 #include "btxv86.h"
32
33 /*
34 * The MBR/VBR is located in first sector of disk/partition.
35 * Read 512B to temporary location and set up relocation. Then
36 * exec relocator.
37 */
38 #define SECTOR_SIZE (512)
39
40 COMMAND_SET(chain, "chain", "chain load boot block from device", command_chain);
41
42 static int
command_chain(int argc,char * argv[])43 command_chain(int argc, char *argv[])
44 {
45 int fd, len, size = SECTOR_SIZE;
46 struct stat st;
47 vm_offset_t mem = 0x100000;
48 struct i386_devdesc *rootdev;
49
50 if (argc == 1) {
51 command_errmsg = "no device or file name specified";
52 return (CMD_ERROR);
53 }
54 if (argc != 2) {
55 command_errmsg = "invalid trailing arguments";
56 return (CMD_ERROR);
57 }
58
59 fd = open(argv[1], O_RDONLY);
60 if (fd == -1) {
61 command_errmsg = "open failed";
62 return (CMD_ERROR);
63 }
64
65 len = strlen(argv[1]);
66 if (argv[1][len-1] != ':') {
67 if (fstat(fd, &st) == -1) {
68 command_errmsg = "stat failed";
69 close(fd);
70 return (CMD_ERROR);
71 }
72 size = st.st_size;
73 } else if (strncmp(argv[1], "disk", 4) != 0) {
74 command_errmsg = "can only use disk device";
75 close(fd);
76 return (CMD_ERROR);
77 }
78
79 i386_getdev((void **)(&rootdev), argv[1], NULL);
80 if (rootdev == NULL) {
81 command_errmsg = "can't determine root device";
82 close(fd);
83 return (CMD_ERROR);
84 }
85
86 if (archsw.arch_readin(fd, mem, size) != size) {
87 command_errmsg = "failed to read disk";
88 close(fd);
89 return (CMD_ERROR);
90 }
91 close(fd);
92
93 if (argv[1][len-1] == ':' &&
94 *((uint16_t *)PTOV(mem + DOSMAGICOFFSET)) != DOSMAGIC) {
95 command_errmsg = "wrong magic";
96 return (CMD_ERROR);
97 }
98
99 relocater_data[0].src = mem;
100 relocater_data[0].dest = 0x7C00;
101 relocater_data[0].size = size;
102
103 relocator_edx = bd_unit2bios(rootdev->d_unit);
104 relocator_esi = relocater_size;
105 relocator_ds = 0;
106 relocator_es = 0;
107 relocator_fs = 0;
108 relocator_gs = 0;
109 relocator_ss = 0;
110 relocator_cs = 0;
111 relocator_sp = 0x7C00;
112 relocator_ip = 0x7C00;
113 relocator_a20_enabled = 0;
114
115 i386_copyin(relocater, 0x600, relocater_size);
116
117 dev_cleanup();
118
119 __exec((void *)0x600);
120
121 panic("exec returned");
122 return (CMD_ERROR); /* not reached */
123 }
124