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  *   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
  18 struct boot_params boot_params __attribute__((aligned(16)));
  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  * Set the keyboard repeat rate to maximum.  Unclear why this
  61  * is done here; this might be possible to kill off as stale code.
  62  */
  63 static void keyboard_set_repeat(void)
  64 {
  65         struct biosregs ireg;
  66         initregs(&ireg);
  67         ireg.ax = 0x0305;
  68         intcall(0x16, &ireg, NULL);
  69 }
  70
  71 /*
  72  * Get Intel SpeedStep (IST) information.
  73  */
  74 static void query_ist(void)
  75 {
  76         struct biosregs ireg, oreg;
  77
  78         /* Some older BIOSes apparently crash on this call, so filter
  79            it from machines too old to have SpeedStep at all. */
  80         if (cpu.level < 6)
  81                 return;
  82
  83         initregs(&ireg);
  84         ireg.ax  = 0xe980;       /* IST Support */
  85         ireg.edx = 0x47534943;   /* Request value */
  86         intcall(0x15, &ireg, &oreg);
  87
  88         boot_params.ist_info.signature  = oreg.eax;
  89         boot_params.ist_info.command    = oreg.ebx;
  90         boot_params.ist_info.event      = oreg.ecx;
  91         boot_params.ist_info.perf_level = oreg.edx;
  92 }
  93
  94 /*
  95  * Tell the BIOS what CPU mode we intend to run in.
  96  */
  97 static void set_bios_mode(void)
  98 {
  99 #ifdef CONFIG_X86_64
 100         struct biosregs ireg;
 101
 102         initregs(&ireg);
 103         ireg.ax = 0xec00;
 104         ireg.bx = 2;
 105         intcall(0x15, &ireg, NULL);
 106 #endif
 107 }
 108
 109 static void init_heap(void)
 110 {
 111         char *stack_end;
 112
 113         if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
 114                 asm("leal %P1(%%esp),%0"
 115                     : "=r" (stack_end) : "i" (-STACK_SIZE));
 116
 117                 heap_end = (char *)
 118                         ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
 119                 if (heap_end > stack_end)
 120                         heap_end = stack_end;
 121         } else {
 122                 /* Boot protocol 2.00 only, no heap available */
 123                 puts("WARNING: Ancient bootloader, some functionality "
 124                      "may be limited!\n");
 125         }
 126 }
 127
 128 void main(void)
 129 {
 130         /* First, copy the boot header into the "zeropage" */
 131         copy_boot_params();
 132
 133         /* Initialize the early-boot console */
 134         console_init();
 135         if (cmdline_find_option_bool("debug"))
 136                 puts("early console in setup code\n");
 137
 138         /* End of heap check */
 139         init_heap();
 140
 141         /* Make sure we have all the proper CPU support */
 142         if (validate_cpu()) {
 143                 puts("Unable to boot - please use a kernel appropriate "
 144                      "for your CPU.\n");
 145                 die();
 146         }
 147
 148         /* Tell the BIOS what CPU mode we intend to run in. */
 149         set_bios_mode();
 150
 151         /* Detect memory layout */
 152         detect_memory();
 153
 154         /* Set keyboard repeat rate (why?) */
 155         keyboard_set_repeat();
 156
 157         /* Query MCA information */
 158         query_mca();
 159
 160         /* Query Intel SpeedStep (IST) information */
 161         query_ist();
 162
 163         /* Query APM information */
 164 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 165         query_apm_bios();
 166 #endif
 167
 168         /* Query EDD information */
 169 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
 170         query_edd();
 171 #endif
 172
 173         /* Set the video mode */
 174         set_video();
 175
 176         /* Do the last things and invoke protected mode */
 177         go_to_protected_mode();
 178 }