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  * 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
  30 static 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  * Set the keyboard repeat rate to maximum.  Unclear why this
  62  * is done here; this might be possible to kill off as stale code.
  63  */
  64 static void keyboard_set_repeat(void)
  65 {
  66         u16 ax = 0x0305;
  67         u16 bx = 0;
  68         asm volatile("int $0x16"
  69                      : "+a" (ax), "+b" (bx)
  70                      : : "ecx", "edx", "esi", "edi");
  71 }
  72
  73 /*
  74  * Get Intel SpeedStep (IST) information.
  75  */
  76 static void query_ist(void)
  77 {
  78         asm("int $0x15"
  79             : "=a" (boot_params.ist_info.signature),
  80               "=b" (boot_params.ist_info.command),
  81               "=c" (boot_params.ist_info.event),
  82               "=d" (boot_params.ist_info.perf_level)
  83             : "a" (0x0000e980),  /* IST Support */
  84               "d" (0x47534943)); /* Request value */
  85 }
  86
  87 /*
  88  * Tell the BIOS what CPU mode we intend to run in.
  89  */
  90 static void set_bios_mode(void)
  91 {
  92 #ifdef CONFIG_X86_64
  93         u32 eax, ebx;
  94
  95         eax = 0xec00;
  96         ebx = 2;
  97         asm volatile("int $0x15"
  98                      : "+a" (eax), "+b" (ebx)
  99                      : : "ecx", "edx", "esi", "edi");
 100 #endif
 101 }
 102
 103 static void init_heap(void)
 104 {
 105         char *stack_end;
 106
 107         if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
 108                 asm("leal %P1(%%esp),%0"
 109                     : "=r" (stack_end) : "i" (-STACK_SIZE));
 110
 111                 heap_end = (char *)
 112                         ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
 113                 if (heap_end > stack_end)
 114                         heap_end = stack_end;
 115         } else {
 116                 /* Boot protocol 2.00 only, no heap available */
 117                 puts("WARNING: Ancient bootloader, some functionality "
 118                      "may be limited!\n");
 119         }
 120 }
 121
 122 void main(void)
 123 {
 124         /* First, copy the boot header into the "zeropage" */
 125         copy_boot_params();
 126
 127         /* End of heap check */
 128         init_heap();
 129
 130         /* Make sure we have all the proper CPU support */
 131         if (validate_cpu()) {
 132                 puts("Unable to boot - please use a kernel appropriate "
 133                      "for your CPU.\n");
 134                 die();
 135         }
 136
 137         /* Tell the BIOS what CPU mode we intend to run in. */
 138         set_bios_mode();
 139
 140         /* Detect memory layout */
 141         detect_memory();
 142
 143         /* Set keyboard repeat rate (why?) */
 144         keyboard_set_repeat();
 145
 146         /* Query MCA information */
 147         query_mca();
 148
 149         /* Voyager */
 150 #ifdef CONFIG_X86_VOYAGER
 151         query_voyager();
 152 #endif
 153
 154         /* Query Intel SpeedStep (IST) information */
 155         query_ist();
 156
 157         /* Query APM information */
 158 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 159         query_apm_bios();
 160 #endif
 161
 162         /* Query EDD information */
 163 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
 164         query_edd();
 165 #endif
 166
 167         /* Set the video mode */
 168         set_video();
 169
 170         /* Do the last things and invoke protected mode */
 171         go_to_protected_mode();
 172 }