LXR linux/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
  18struct boot_params boot_params __attribute__((aligned(16)));
  19
  20char *HEAP = _end;
  21char *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
  29static 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 */
  63static 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 */
  74static 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 */
  97static 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
 109static 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
 128void main(void)
 129{
 130        /* First, copy the boot header into the "zeropage" */
 131        copy_boot_params();
 132
 133        /* End of heap check */
 134        init_heap();
 135
 136        /* Make sure we have all the proper CPU support */
 137        if (validate_cpu()) {
 138                puts("Unable to boot - please use a kernel appropriate "
 139                     "for your CPU.\n");
 140                die();
 141        }
 142
 143        /* Tell the BIOS what CPU mode we intend to run in. */
 144        set_bios_mode();
 145
 146        /* Detect memory layout */
 147        detect_memory();
 148
 149        /* Set keyboard repeat rate (why?) */
 150        keyboard_set_repeat();
 151
 152        /* Query MCA information */
 153        query_mca();
 154
 155        /* Query Intel SpeedStep (IST) information */
 156        query_ist();
 157
 158        /* Query APM information */
 159#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 160        query_apm_bios();
 161#endif
 162
 163        /* Query EDD information */
 164#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
 165        query_edd();
 166#endif
 167
 168        /* Set the video mode */
 169        set_video();
 170
 171        /* Parse command line for 'quiet' and pass it to decompressor. */
 172        if (cmdline_find_option_bool("quiet"))
 173                boot_params.hdr.loadflags |= QUIET_FLAG;
 174
 175        /* Do the last things and invoke protected mode */
 176        go_to_protected_mode();
 177}
 178