1 /* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright 2007 rPath, Inc. - All Rights Reserved
5 *
6 * This file is part of the Linux kernel, and is made available under
7 * the terms of the GNU General Public License version 2.
8 *
9 * ----------------------------------------------------------------------- */
10
11 /*
12 * Main module for the real-mode kernel code
13 */
14
15 #include "boot.h"
16
17 struct boot_params boot_params __attribute__((aligned(16)));
18
19 char *HEAP = _end;
20 char *heap_end = _end; /* Default end of heap = no heap */
21
22 /*
23 * Copy the header into the boot parameter block. Since this
24 * screws up the old-style command line protocol, adjust by
25 * filling in the new-style command line pointer instead.
26 */
27
copy_boot_params(void)28 static void copy_boot_params(void)
29 {
30 struct old_cmdline {
31 u16 cl_magic;
32 u16 cl_offset;
33 };
34 const struct old_cmdline * const oldcmd =
35 (const struct old_cmdline *)OLD_CL_ADDRESS;
36
37 BUILD_BUG_ON(sizeof boot_params != 4096);
38 memcpy(&boot_params.hdr, &hdr, sizeof hdr);
39
40 if (!boot_params.hdr.cmd_line_ptr &&
41 oldcmd->cl_magic == OLD_CL_MAGIC) {
42 /* Old-style command line protocol. */
43 u16 cmdline_seg;
44
45 /* Figure out if the command line falls in the region
46 of memory that an old kernel would have copied up
47 to 0x90000... */
48 if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
49 cmdline_seg = ds();
50 else
51 cmdline_seg = 0x9000;
52
53 boot_params.hdr.cmd_line_ptr =
54 (cmdline_seg << 4) + oldcmd->cl_offset;
55 }
56 }
57
58 /*
59 * Set the keyboard repeat rate to maximum. Unclear why this
60 * is done here; this might be possible to kill off as stale code.
61 */
keyboard_set_repeat(void)62 static void keyboard_set_repeat(void)
63 {
64 u16 ax = 0x0305;
65 u16 bx = 0;
66 asm volatile("int $0x16"
67 : "+a" (ax), "+b" (bx)
68 : : "ecx", "edx", "esi", "edi");
69 }
70
71 /*
72 * Get Intel SpeedStep (IST) information.
73 */
query_ist(void)74 static void query_ist(void)
75 {
76 /* Some older BIOSes apparently crash on this call, so filter
77 it from machines too old to have SpeedStep at all. */
78 if (cpu.level < 6)
79 return;
80
81 asm("int $0x15"
82 : "=a" (boot_params.ist_info.signature),
83 "=b" (boot_params.ist_info.command),
84 "=c" (boot_params.ist_info.event),
85 "=d" (boot_params.ist_info.perf_level)
86 : "a" (0x0000e980), /* IST Support */
87 "d" (0x47534943)); /* Request value */
88 }
89
90 /*
91 * Tell the BIOS what CPU mode we intend to run in.
92 */
set_bios_mode(void)93 static void set_bios_mode(void)
94 {
95 #ifdef CONFIG_X86_64
96 u32 eax, ebx;
97
98 eax = 0xec00;
99 ebx = 2;
100 asm volatile("int $0x15"
101 : "+a" (eax), "+b" (ebx)
102 : : "ecx", "edx", "esi", "edi");
103 #endif
104 }
105
init_heap(void)106 static void init_heap(void)
107 {
108 char *stack_end;
109
110 if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
111 asm("leal %P1(%%esp),%0"
112 : "=r" (stack_end) : "i" (-STACK_SIZE));
113
114 heap_end = (char *)
115 ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
116 if (heap_end > stack_end)
117 heap_end = stack_end;
118 } else {
119 /* Boot protocol 2.00 only, no heap available */
120 puts("WARNING: Ancient bootloader, some functionality "
121 "may be limited!\n");
122 }
123 }
124
main(void)125 void main(void)
126 {
127 /* First, copy the boot header into the "zeropage" */
128 copy_boot_params();
129
130 /* End of heap check */
131 init_heap();
132
133 /* Make sure we have all the proper CPU support */
134 if (validate_cpu()) {
135 puts("Unable to boot - please use a kernel appropriate "
136 "for your CPU.\n");
137 die();
138 }
139
140 /* Tell the BIOS what CPU mode we intend to run in. */
141 set_bios_mode();
142
143 /* Detect memory layout */
144 detect_memory();
145
146 /* Set keyboard repeat rate (why?) */
147 keyboard_set_repeat();
148
149 /* Query MCA information */
150 query_mca();
151
152 /* Voyager */
153 #ifdef CONFIG_X86_VOYAGER
154 query_voyager();
155 #endif
156
157 /* Query Intel SpeedStep (IST) information */
158 query_ist();
159
160 /* Query APM information */
161 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
162 query_apm_bios();
163 #endif
164
165 /* Query EDD information */
166 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
167 query_edd();
168 #endif
169
170 /* Set the video mode */
171 set_video();
172
173 /* Parse command line for 'quiet' and pass it to decompressor. */
174 if (cmdline_find_option_bool("quiet"))
175 boot_params.hdr.loadflags |= QUIET_FLAG;
176
177 /* Do the last things and invoke protected mode */
178 go_to_protected_mode();
179 }
180