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
  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  * 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  */
  65 static 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  */
  81 static 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  */
 104 static 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
 116 static 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
 135 void 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 }