Linux Kernel  3.7.1
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main.c
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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 
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 
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  * Query the keyboard lock status as given by the BIOS, and
61  * set the keyboard repeat rate to maximum. Unclear why the latter
62  * is done here; this might be possible to kill off as stale code.
63  */
64 static void keyboard_init(void)
65 {
66  struct biosregs ireg, oreg;
67  initregs(&ireg);
68 
69  ireg.ah = 0x02; /* Get keyboard status */
70  intcall(0x16, &ireg, &oreg);
71  boot_params.kbd_status = oreg.al;
72 
73  ireg.ax = 0x0305; /* Set keyboard repeat rate */
74  intcall(0x16, &ireg, NULL);
75 }
76 
77 /*
78  * Get Intel SpeedStep (IST) information.
79  */
80 static void query_ist(void)
81 {
82  struct biosregs ireg, oreg;
83 
84  /* Some older BIOSes apparently crash on this call, so filter
85  it from machines too old to have SpeedStep at all. */
86  if (cpu.level < 6)
87  return;
88 
89  initregs(&ireg);
90  ireg.ax = 0xe980; /* IST Support */
91  ireg.edx = 0x47534943; /* Request value */
92  intcall(0x15, &ireg, &oreg);
93 
94  boot_params.ist_info.signature = oreg.eax;
95  boot_params.ist_info.command = oreg.ebx;
96  boot_params.ist_info.event = oreg.ecx;
97  boot_params.ist_info.perf_level = oreg.edx;
98 }
99 
100 /*
101  * Tell the BIOS what CPU mode we intend to run in.
102  */
103 static void set_bios_mode(void)
104 {
105 #ifdef CONFIG_X86_64
106  struct biosregs ireg;
107 
108  initregs(&ireg);
109  ireg.ax = 0xec00;
110  ireg.bx = 2;
111  intcall(0x15, &ireg, NULL);
112 #endif
113 }
114 
115 static void init_heap(void)
116 {
117  char *stack_end;
118 
119  if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
120  asm("leal %P1(%%esp),%0"
121  : "=r" (stack_end) : "i" (-STACK_SIZE));
122 
123  heap_end = (char *)
124  ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
125  if (heap_end > stack_end)
126  heap_end = stack_end;
127  } else {
128  /* Boot protocol 2.00 only, no heap available */
129  puts("WARNING: Ancient bootloader, some functionality "
130  "may be limited!\n");
131  }
132 }
133 
134 void main(void)
135 {
136  /* First, copy the boot header into the "zeropage" */
137  copy_boot_params();
138 
139  /* Initialize the early-boot console */
140  console_init();
141  if (cmdline_find_option_bool("debug"))
142  puts("early console in setup code\n");
143 
144  /* End of heap check */
145  init_heap();
146 
147  /* Make sure we have all the proper CPU support */
148  if (validate_cpu()) {
149  puts("Unable to boot - please use a kernel appropriate "
150  "for your CPU.\n");
151  die();
152  }
153 
154  /* Tell the BIOS what CPU mode we intend to run in. */
155  set_bios_mode();
156 
157  /* Detect memory layout */
158  detect_memory();
159 
160  /* Set keyboard repeat rate (why?) and query the lock flags */
161  keyboard_init();
162 
163  /* Query MCA information */
164  query_mca();
165 
166  /* Query Intel SpeedStep (IST) information */
167  query_ist();
168 
169  /* Query APM information */
170 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
171  query_apm_bios();
172 #endif
173 
174  /* Query EDD information */
175 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
176  query_edd();
177 #endif
178 
179  /* Set the video mode */
180  set_video();
181 
182  /* Do the last things and invoke protected mode */
184 }