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#include "string.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 * Query the keyboard lock status as given by the BIOS, and
  62 * set the keyboard repeat rate to maximum.  Unclear why the latter
  63 * is done here; this might be possible to kill off as stale code.
  64 */
  65static void keyboard_init(void)
  66{
  67        struct biosregs ireg, oreg;
  68        initregs(&ireg);
  69
  70        ireg.ah = 0x02;         /* Get keyboard status */
  71        intcall(0x16, &ireg, &oreg);
  72        boot_params.kbd_status = oreg.al;
  73
  74        ireg.ax = 0x0305;       /* Set keyboard repeat rate */
  75        intcall(0x16, &ireg, NULL);
  76}
  77
  78/*
  79 * Get Intel SpeedStep (IST) information.
  80 */
  81static void query_ist(void)
  82{
  83        struct biosregs ireg, oreg;
  84
  85        /* Some older BIOSes apparently crash on this call, so filter
  86           it from machines too old to have SpeedStep at all. */
  87        if (cpu.level < 6)
  88                return;
  89
  90        initregs(&ireg);
  91        ireg.ax  = 0xe980;       /* IST Support */
  92        ireg.edx = 0x47534943;   /* Request value */
  93        intcall(0x15, &ireg, &oreg);
  94
  95        boot_params.ist_info.signature  = oreg.eax;
  96        boot_params.ist_info.command    = oreg.ebx;
  97        boot_params.ist_info.event      = oreg.ecx;
  98        boot_params.ist_info.perf_level = oreg.edx;
  99}
 100
 101/*
 102 * Tell the BIOS what CPU mode we intend to run in.
 103 */
 104static void set_bios_mode(void)
 105{
 106#ifdef CONFIG_X86_64
 107        struct biosregs ireg;
 108
 109        initregs(&ireg);
 110        ireg.ax = 0xec00;
 111        ireg.bx = 2;
 112        intcall(0x15, &ireg, NULL);
 113#endif
 114}
 115
 116static void init_heap(void)
 117{
 118        char *stack_end;
 119
 120        if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
 121                asm("leal %P1(%%esp),%0"
 122                    : "=r" (stack_end) : "i" (-STACK_SIZE));
 123
 124                heap_end = (char *)
 125                        ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
 126                if (heap_end > stack_end)
 127                        heap_end = stack_end;
 128        } else {
 129                /* Boot protocol 2.00 only, no heap available */
 130                puts("WARNING: Ancient bootloader, some functionality "
 131                     "may be limited!\n");
 132        }
 133}
 134
 135void main(void)
 136{
 137        /* First, copy the boot header into the "zeropage" */
 138        copy_boot_params();
 139
 140        /* Initialize the early-boot console */
 141        console_init();
 142        if (cmdline_find_option_bool("debug"))
 143                puts("early console in setup code\n");
 144
 145        /* End of heap check */
 146        init_heap();
 147
 148        /* Make sure we have all the proper CPU support */
 149        if (validate_cpu()) {
 150                puts("Unable to boot - please use a kernel appropriate "
 151                     "for your CPU.\n");
 152                die();
 153        }
 154
 155        /* Tell the BIOS what CPU mode we intend to run in. */
 156        set_bios_mode();
 157
 158        /* Detect memory layout */
 159        detect_memory();
 160
 161        /* Set keyboard repeat rate (why?) and query the lock flags */
 162        keyboard_init();
 163
 164        /* Query Intel SpeedStep (IST) information */
 165        query_ist();
 166
 167        /* Query APM information */
 168#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 169        query_apm_bios();
 170#endif
 171
 172        /* Query EDD information */
 173#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
 174        query_edd();
 175#endif
 176
 177        /* Set the video mode */
 178        set_video();
 179
 180        /* Do the last things and invoke protected mode */
 181        go_to_protected_mode();
 182}
 183