arch/i386/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  * arch/i386/boot/main.c
  13  *
  14  * Main module for the real-mode kernel code
  15  */
  16
  17 #include "boot.h"
  18
  19 struct boot_params boot_params __attribute__((aligned(16)));
  20
  21 char *HEAP = _end;
  22 char *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 #define OLD_CL_MAGIC    0xA33F
  30 #define OLD_CL_ADDRESS  0x20
  31
  32 static void copy_boot_params(void)
  33 {
  34         struct old_cmdline {
  35                 u16 cl_magic;
  36                 u16 cl_offset;
  37         };
  38         const struct old_cmdline * const oldcmd =
  39                 (const struct old_cmdline *)OLD_CL_ADDRESS;
  40
  41         BUILD_BUG_ON(sizeof boot_params != 4096);
  42         memcpy(&boot_params.hdr, &hdr, sizeof hdr);
  43
  44         if (!boot_params.hdr.cmd_line_ptr &&
  45             oldcmd->cl_magic == OLD_CL_MAGIC) {
  46                 /* Old-style command line protocol. */
  47                 u16 cmdline_seg;
  48
  49                 /* Figure out if the command line falls in the region
  50                    of memory that an old kernel would have copied up
  51                    to 0x90000... */
  52                 if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
  53                         cmdline_seg = ds();
  54                 else
  55                         cmdline_seg = 0x9000;
  56
  57                 boot_params.hdr.cmd_line_ptr =
  58                         (cmdline_seg << 4) + oldcmd->cl_offset;
  59         }
  60 }
  61
  62 /*
  63  * Set the keyboard repeat rate to maximum.  Unclear why this
  64  * is done here; this might be possible to kill off as stale code.
  65  */
  66 static void keyboard_set_repeat(void)
  67 {
  68         u16 ax = 0x0305;
  69         u16 bx = 0;
  70         asm volatile("int $0x16"
  71                      : "+a" (ax), "+b" (bx)
  72                      : : "ecx", "edx", "esi", "edi");
  73 }
  74
  75 /*
  76  * Get Intel SpeedStep (IST) information.
  77  */
  78 static void query_ist(void)
  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 void main(void)
 106 {
 107         /* First, copy the boot header into the "zeropage" */
 108         copy_boot_params();
 109
 110         /* End of heap check */
 111         if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
 112                 heap_end = (char *)(boot_params.hdr.heap_end_ptr
 113                                     +0x200-STACK_SIZE);
 114         } else {
 115                 /* Boot protocol 2.00 only, no heap available */
 116                 puts("WARNING: Ancient bootloader, some functionality "
 117                      "may be limited!\n");
 118         }
 119
 120         /* Make sure we have all the proper CPU support */
 121         if (validate_cpu()) {
 122                 puts("Unable to boot - please use a kernel appropriate "
 123                      "for your CPU.\n");
 124                 die();
 125         }
 126
 127         /* Tell the BIOS what CPU mode we intend to run in. */
 128         set_bios_mode();
 129
 130         /* Detect memory layout */
 131         detect_memory();
 132
 133         /* Set keyboard repeat rate (why?) */
 134         keyboard_set_repeat();
 135
 136         /* Set the video mode */
 137         set_video();
 138
 139         /* Query MCA information */
 140         query_mca();
 141
 142         /* Voyager */
 143 #ifdef CONFIG_X86_VOYAGER
 144         query_voyager();
 145 #endif
 146
 147         /* Query Intel SpeedStep (IST) information */
 148         query_ist();
 149
 150         /* Query APM information */
 151 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 152         query_apm_bios();
 153 #endif
 154
 155         /* Query EDD information */
 156 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
 157         query_edd();
 158 #endif
 159         /* Do the last things and invoke protected mode */
 160         go_to_protected_mode();
 161 }