linux/arch/x86/boot/main.c
<<
>>
Prefs
   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
  19struct boot_params boot_params __attribute__((aligned(16)));
  20
  21char *HEAP = _end;
  22char *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
  30static 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 */
  64static 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 */
  76static 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 */
  90static 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
 103static 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
 122void 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}
 173
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.