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         /* Some 486 BIOSes apparently crash on this call */
  77         if (cpu.level < 6)
  78                 return;
  79
  80         asm("int $0x15"
  81             : "=a" (boot_params.ist_info.signature),
  82               "=b" (boot_params.ist_info.command),
  83               "=c" (boot_params.ist_info.event),
  84               "=d" (boot_params.ist_info.perf_level)
  85             : "a" (0x0000e980),  /* IST Support */
  86               "d" (0x47534943)); /* Request value */
  87 }
  88
  89 /*
  90  * Tell the BIOS what CPU mode we intend to run in.
  91  */
  92 static void set_bios_mode(void)
  93 {
  94 #ifdef CONFIG_X86_64
  95         u32 eax, ebx;
  96
  97         eax = 0xec00;
  98         ebx = 2;
  99         asm volatile("int $0x15"
 100                      : "+a" (eax), "+b" (ebx)
 101                      : : "ecx", "edx", "esi", "edi");
 102 #endif
 103 }
 104
 105 static void init_heap(void)
 106 {
 107         char *stack_end;
 108
 109         if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
 110                 asm("leal %P1(%%esp),%0"
 111                     : "=r" (stack_end) : "i" (-STACK_SIZE));
 112
 113                 heap_end = (char *)
 114                         ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
 115                 if (heap_end > stack_end)
 116                         heap_end = stack_end;
 117         } else {
 118                 /* Boot protocol 2.00 only, no heap available */
 119                 puts("WARNING: Ancient bootloader, some functionality "
 120                      "may be limited!\n");
 121         }
 122 }
 123
 124 void main(void)
 125 {
 126         /* First, copy the boot header into the "zeropage" */
 127         copy_boot_params();
 128
 129         /* End of heap check */
 130         init_heap();
 131
 132         /* Make sure we have all the proper CPU support */
 133         if (validate_cpu()) {
 134                 puts("Unable to boot - please use a kernel appropriate "
 135                      "for your CPU.\n");
 136                 die();
 137         }
 138
 139         /* Tell the BIOS what CPU mode we intend to run in. */
 140         set_bios_mode();
 141
 142         /* Detect memory layout */
 143         detect_memory();
 144
 145         /* Set keyboard repeat rate (why?) */
 146         keyboard_set_repeat();
 147
 148         /* Query MCA information */
 149         query_mca();
 150
 151         /* Voyager */
 152 #ifdef CONFIG_X86_VOYAGER
 153         query_voyager();
 154 #endif
 155
 156         /* Query Intel SpeedStep (IST) information */
 157         query_ist();
 158
 159         /* Query APM information */
 160 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 161         query_apm_bios();
 162 #endif
 163
 164         /* Query EDD information */
 165 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
 166         query_edd();
 167 #endif
 168
 169         /* Set the video mode */
 170         set_video();
 171
 172         /* Parse command line for 'quiet' and pass it to decompressor. */
 173         if (cmdline_find_option_bool("quiet"))
 174                 boot_params.hdr.loadflags |= QUIET_FLAG;
 175
 176         /* Do the last things and invoke protected mode */
 177         go_to_protected_mode();
 178 }