1 /* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright 2007 rPath, Inc. - All Rights Reserved
5 * Copyright 2009 Intel Corporation; author H. Peter Anvin
6 *
7 * This file is part of the Linux kernel, and is made available under
8 * the terms of the GNU General Public License version 2.
9 *
10 * ----------------------------------------------------------------------- */
11
12 /*
13 * Main module for the real-mode kernel code
14 */
15
16 #include "boot.h"
17
18 struct boot_params boot_params __attribute__((aligned(16)));
19
20 char *HEAP = _end;
21 char *heap_end = _end; /* Default end of heap = no heap */
22
23 /*
24 * Copy the header into the boot parameter block. Since this
25 * screws up the old-style command line protocol, adjust by
26 * filling in the new-style command line pointer instead.
27 */
28
copy_boot_params(void)29 static void copy_boot_params(void)
30 {
31 struct old_cmdline {
32 u16 cl_magic;
33 u16 cl_offset;
34 };
35 const struct old_cmdline * const oldcmd =
36 (const struct old_cmdline *)OLD_CL_ADDRESS;
37
38 BUILD_BUG_ON(sizeof boot_params != 4096);
39 memcpy(&boot_params.hdr, &hdr, sizeof hdr);
40
41 if (!boot_params.hdr.cmd_line_ptr &&
42 oldcmd->cl_magic == OLD_CL_MAGIC) {
43 /* Old-style command line protocol. */
44 u16 cmdline_seg;
45
46 /* Figure out if the command line falls in the region
47 of memory that an old kernel would have copied up
48 to 0x90000... */
49 if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
50 cmdline_seg = ds();
51 else
52 cmdline_seg = 0x9000;
53
54 boot_params.hdr.cmd_line_ptr =
55 (cmdline_seg << 4) + oldcmd->cl_offset;
56 }
57 }
58
59 /*
60 * Set the keyboard repeat rate to maximum. Unclear why this
61 * is done here; this might be possible to kill off as stale code.
62 */
keyboard_set_repeat(void)63 static void keyboard_set_repeat(void)
64 {
65 struct biosregs ireg;
66 initregs(&ireg);
67 ireg.ax = 0x0305;
68 intcall(0x16, &ireg, NULL);
69 }
70
71 /*
72 * Get Intel SpeedStep (IST) information.
73 */
query_ist(void)74 static void query_ist(void)
75 {
76 struct biosregs ireg, oreg;
77
78 /* Some older BIOSes apparently crash on this call, so filter
79 it from machines too old to have SpeedStep at all. */
80 if (cpu.level < 6)
81 return;
82
83 initregs(&ireg);
84 ireg.ax = 0xe980; /* IST Support */
85 ireg.edx = 0x47534943; /* Request value */
86 intcall(0x15, &ireg, &oreg);
87
88 boot_params.ist_info.signature = oreg.eax;
89 boot_params.ist_info.command = oreg.ebx;
90 boot_params.ist_info.event = oreg.ecx;
91 boot_params.ist_info.perf_level = oreg.edx;
92 }
93
94 /*
95 * Tell the BIOS what CPU mode we intend to run in.
96 */
set_bios_mode(void)97 static void set_bios_mode(void)
98 {
99 #ifdef CONFIG_X86_64
100 struct biosregs ireg;
101
102 initregs(&ireg);
103 ireg.ax = 0xec00;
104 ireg.bx = 2;
105 intcall(0x15, &ireg, NULL);
106 #endif
107 }
108
init_heap(void)109 static void init_heap(void)
110 {
111 char *stack_end;
112
113 if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
114 asm("leal %P1(%%esp),%0"
115 : "=r" (stack_end) : "i" (-STACK_SIZE));
116
117 heap_end = (char *)
118 ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
119 if (heap_end > stack_end)
120 heap_end = stack_end;
121 } else {
122 /* Boot protocol 2.00 only, no heap available */
123 puts("WARNING: Ancient bootloader, some functionality "
124 "may be limited!\n");
125 }
126 }
127
main(void)128 void main(void)
129 {
130 /* First, copy the boot header into the "zeropage" */
131 copy_boot_params();
132
133 /* Initialize the early-boot console */
134 console_init();
135 if (cmdline_find_option_bool("debug"))
136 puts("early console in setup code\n");
137
138 /* End of heap check */
139 init_heap();
140
141 /* Make sure we have all the proper CPU support */
142 if (validate_cpu()) {
143 puts("Unable to boot - please use a kernel appropriate "
144 "for your CPU.\n");
145 die();
146 }
147
148 /* Tell the BIOS what CPU mode we intend to run in. */
149 set_bios_mode();
150
151 /* Detect memory layout */
152 detect_memory();
153
154 /* Set keyboard repeat rate (why?) */
155 keyboard_set_repeat();
156
157 /* Query MCA information */
158 query_mca();
159
160 /* Query Intel SpeedStep (IST) information */
161 query_ist();
162
163 /* Query APM information */
164 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
165 query_apm_bios();
166 #endif
167
168 /* Query EDD information */
169 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
170 query_edd();
171 #endif
172
173 /* Set the video mode */
174 set_video();
175
176 /* Do the last things and invoke protected mode */
177 go_to_protected_mode();
178 }
179