arch/x86/boot/main.c

   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
  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  */
  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  */
  74 static void query_ist(void)
  75 {
  76         asm("int $0x15"
  77             : "=a" (boot_params.ist_info.signature),
  78               "=b" (boot_params.ist_info.command),
  79               "=c" (boot_params.ist_info.event),
  80               "=d" (boot_params.ist_info.perf_level)
  81             : "a" (0x0000e980),  /* IST Support */
  82               "d" (0x47534943)); /* Request value */
  83 }
  84
  85 /*
  86  * Tell the BIOS what CPU mode we intend to run in.
  87  */
  88 static void set_bios_mode(void)
  89 {
  90 #ifdef CONFIG_X86_64
  91         u32 eax, ebx;
  92
  93         eax = 0xec00;
  94         ebx = 2;
  95         asm volatile("int $0x15"
  96                      : "+a" (eax), "+b" (ebx)
  97                      : : "ecx", "edx", "esi", "edi");
  98 #endif
  99 }
 100
 101 static void init_heap(void)
 102 {
 103         char *stack_end;
 104
 105         if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
 106                 asm("leal %P1(%%esp),%0"
 107                     : "=r" (stack_end) : "i" (-STACK_SIZE));
 108
 109                 heap_end = (char *)
 110                         ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
 111                 if (heap_end > stack_end)
 112                         heap_end = stack_end;
 113         } else {
 114                 /* Boot protocol 2.00 only, no heap available */
 115                 puts("WARNING: Ancient bootloader, some functionality "
 116                      "may be limited!\n");
 117         }
 118 }
 119
 120 void main(void)
 121 {
 122         /* First, copy the boot header into the "zeropage" */
 123         copy_boot_params();
 124
 125         /* End of heap check */
 126         init_heap();
 127
 128         /* Make sure we have all the proper CPU support */
 129         if (validate_cpu()) {
 130                 puts("Unable to boot - please use a kernel appropriate "
 131                      "for your CPU.\n");
 132                 die();
 133         }
 134
 135         /* Tell the BIOS what CPU mode we intend to run in. */
 136         set_bios_mode();
 137
 138         /* Detect memory layout */
 139         detect_memory();
 140
 141         /* Set keyboard repeat rate (why?) */
 142         keyboard_set_repeat();
 143
 144         /* Query MCA information */
 145         query_mca();
 146
 147         /* Voyager */
 148 #ifdef CONFIG_X86_VOYAGER
 149         query_voyager();
 150 #endif
 151
 152         /* Query Intel SpeedStep (IST) information */
 153         query_ist();
 154
 155         /* Query APM information */
 156 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 157         query_apm_bios();
 158 #endif
 159
 160         /* Query EDD information */
 161 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
 162         query_edd();
 163 #endif
 164
 165         /* Set the video mode */
 166         set_video();
 167
 168         /* Do the last things and invoke protected mode */
 169         go_to_protected_mode();
 170 }