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#include "string.h"
18
19struct boot_params boot_params __attribute__((aligned(16)));
20
21char *HEAP = _end;
22char *heap_end = _end; /* Default end of heap = no heap */
23
24/*
25 * Copy the header into the boot parameter block. Since this
26 * screws up the old-style command line protocol, adjust by
27 * filling in the new-style command line pointer instead.
28 */
29
30static void copy_boot_params(void)
31{
32 struct old_cmdline {
33 u16 cl_magic;
34 u16 cl_offset;
35 };
36 const struct old_cmdline * const oldcmd =
37 (const struct old_cmdline *)OLD_CL_ADDRESS;
38
39 BUILD_BUG_ON(sizeof(boot_params) != 4096);
40 memcpy(&boot_params.hdr, &hdr, sizeof(hdr));
41
42 if (!boot_params.hdr.cmd_line_ptr &&
43 oldcmd->cl_magic == OLD_CL_MAGIC) {
44 /* Old-style command line protocol. */
45 u16 cmdline_seg;
46
47 /* Figure out if the command line falls in the region
48 of memory that an old kernel would have copied up
49 to 0x90000... */
50 if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
51 cmdline_seg = ds();
52 else
53 cmdline_seg = 0x9000;
54
55 boot_params.hdr.cmd_line_ptr =
56 (cmdline_seg << 4) + oldcmd->cl_offset;
57 }
58}
59
60/*
61 * Query the keyboard lock status as given by the BIOS, and
62 * set the keyboard repeat rate to maximum. Unclear why the latter
63 * is done here; this might be possible to kill off as stale code.
64 */
65static void keyboard_init(void)
66{
67 struct biosregs ireg, oreg;
68 initregs(&ireg);
69
70 ireg.ah = 0x02; /* Get keyboard status */
71 intcall(0x16, &ireg, &oreg);
72 boot_params.kbd_status = oreg.al;
73
74 ireg.ax = 0x0305; /* Set keyboard repeat rate */
75 intcall(0x16, &ireg, NULL);
76}
77
78/*
79 * Get Intel SpeedStep (IST) information.
80 */
81static void query_ist(void)
82{
83 struct biosregs ireg, oreg;
84
85 /* Some older BIOSes apparently crash on this call, so filter
86 it from machines too old to have SpeedStep at all. */
87 if (cpu.level < 6)
88 return;
89
90 initregs(&ireg);
91 ireg.ax = 0xe980; /* IST Support */
92 ireg.edx = 0x47534943; /* Request value */
93 intcall(0x15, &ireg, &oreg);
94
95 boot_params.ist_info.signature = oreg.eax;
96 boot_params.ist_info.command = oreg.ebx;
97 boot_params.ist_info.event = oreg.ecx;
98 boot_params.ist_info.perf_level = oreg.edx;
99}
100
101/*
102 * Tell the BIOS what CPU mode we intend to run in.
103 */
104static void set_bios_mode(void)
105{
106#ifdef CONFIG_X86_64
107 struct biosregs ireg;
108
109 initregs(&ireg);
110 ireg.ax = 0xec00;
111 ireg.bx = 2;
112 intcall(0x15, &ireg, NULL);
113#endif
114}
115
116static void init_heap(void)
117{
118 char *stack_end;
119
120 if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
121 asm("leal %P1(%%esp),%0"
122 : "=r" (stack_end) : "i" (-STACK_SIZE));
123
124 heap_end = (char *)
125 ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
126 if (heap_end > stack_end)
127 heap_end = stack_end;
128 } else {
129 /* Boot protocol 2.00 only, no heap available */
130 puts("WARNING: Ancient bootloader, some functionality "
131 "may be limited!\n");
132 }
133}
134
135void main(void)
136{
137 /* First, copy the boot header into the "zeropage" */
138 copy_boot_params();
139
140 /* Initialize the early-boot console */
141 console_init();
142 if (cmdline_find_option_bool("debug"))
143 puts("early console in setup code\n");
144
145 /* End of heap check */
146 init_heap();
147
148 /* Make sure we have all the proper CPU support */
149 if (validate_cpu()) {
150 puts("Unable to boot - please use a kernel appropriate "
151 "for your CPU.\n");
152 die();
153 }
154
155 /* Tell the BIOS what CPU mode we intend to run in. */
156 set_bios_mode();
157
158 /* Detect memory layout */
159 detect_memory();
160
161 /* Set keyboard repeat rate (why?) and query the lock flags */
162 keyboard_init();
163
164 /* Query Intel SpeedStep (IST) information */
165 query_ist();
166
167 /* Query APM information */
168#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
169 query_apm_bios();
170#endif
171
172 /* Query EDD information */
173#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
174 query_edd();
175#endif
176
177 /* Set the video mode */
178 set_video();
179
180 /* Do the last things and invoke protected mode */
181 go_to_protected_mode();
182}
183