kernel/2.6.29.6-aldebaran-rt/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  *
   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  * Main module for the real-mode kernel code
  13  */
  14
  15 #include "boot.h"
  16
  17 struct boot_params boot_params __attribute__((aligned(16)));
  18
  19 char *HEAP = _end;
  20 char *heap_end = _end;          /* Default end of heap = no heap */
  21
  22 /*
  23  * Copy the header into the boot parameter block.  Since this
  24  * screws up the old-style command line protocol, adjust by
  25  * filling in the new-style command line pointer instead.
  26  */
  27
  28 static void copy_boot_params(void)
  29 {
  30         struct old_cmdline {
  31                 u16 cl_magic;
  32                 u16 cl_offset;
  33         };
  34         const struct old_cmdline * const oldcmd =
  35                 (const struct old_cmdline *)OLD_CL_ADDRESS;
  36
  37         BUILD_BUG_ON(sizeof boot_params != 4096);
  38         memcpy(&boot_params.hdr, &hdr, sizeof hdr);
  39
  40         if (!boot_params.hdr.cmd_line_ptr &&
  41             oldcmd->cl_magic == OLD_CL_MAGIC) {
  42                 /* Old-style command line protocol. */
  43                 u16 cmdline_seg;
  44
  45                 /* Figure out if the command line falls in the region
  46                    of memory that an old kernel would have copied up
  47                    to 0x90000... */
  48                 if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
  49                         cmdline_seg = ds();
  50                 else
  51                         cmdline_seg = 0x9000;
  52
  53                 boot_params.hdr.cmd_line_ptr =
  54                         (cmdline_seg << 4) + oldcmd->cl_offset;
  55         }
  56 }
  57
  58 /*
  59  * Set the keyboard repeat rate to maximum.  Unclear why this
  60  * is done here; this might be possible to kill off as stale code.
  61  */
  62 static void keyboard_set_repeat(void)
  63 {
  64         u16 ax = 0x0305;
  65         u16 bx = 0;
  66         asm volatile("int $0x16"
  67                      : "+a" (ax), "+b" (bx)
  68                      : : "ecx", "edx", "esi", "edi");
  69 }
  70
  71 /*
  72  * Get Intel SpeedStep (IST) information.
  73  */
  74 static void query_ist(void)
  75 {
  76         /* Some older BIOSes apparently crash on this call, so filter
  77            it from machines too old to have SpeedStep at all. */
  78         if (cpu.level < 6)
  79                 return;
  80
  81         asm("int $0x15"
  82             : "=a" (boot_params.ist_info.signature),
  83               "=b" (boot_params.ist_info.command),
  84               "=c" (boot_params.ist_info.event),
  85               "=d" (boot_params.ist_info.perf_level)
  86             : "a" (0x0000e980),  /* IST Support */
  87               "d" (0x47534943)); /* Request value */
  88 }
  89
  90 /*
  91  * Tell the BIOS what CPU mode we intend to run in.
  92  */
  93 static void set_bios_mode(void)
  94 {
  95 #ifdef CONFIG_X86_64
  96         u32 eax, ebx;
  97
  98         eax = 0xec00;
  99         ebx = 2;
 100         asm volatile("int $0x15"
 101                      : "+a" (eax), "+b" (ebx)
 102                      : : "ecx", "edx", "esi", "edi");
 103 #endif
 104 }
 105
 106 static void init_heap(void)
 107 {
 108         char *stack_end;
 109
 110         if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
 111                 asm("leal %P1(%%esp),%0"
 112                     : "=r" (stack_end) : "i" (-STACK_SIZE));
 113
 114                 heap_end = (char *)
 115                         ((size_t)boot_params.hdr.heap_end_ptr + 0x200);
 116                 if (heap_end > stack_end)
 117                         heap_end = stack_end;
 118         } else {
 119                 /* Boot protocol 2.00 only, no heap available */
 120                 puts("WARNING: Ancient bootloader, some functionality "
 121                      "may be limited!\n");
 122         }
 123 }
 124
 125 void main(void)
 126 {
 127         /* First, copy the boot header into the "zeropage" */
 128         copy_boot_params();
 129
 130         /* End of heap check */
 131         init_heap();
 132
 133         /* Make sure we have all the proper CPU support */
 134         if (validate_cpu()) {
 135                 puts("Unable to boot - please use a kernel appropriate "
 136                      "for your CPU.\n");
 137                 die();
 138         }
 139
 140         /* Tell the BIOS what CPU mode we intend to run in. */
 141         set_bios_mode();
 142
 143         /* Detect memory layout */
 144         detect_memory();
 145
 146         /* Set keyboard repeat rate (why?) */
 147         keyboard_set_repeat();
 148
 149         /* Query MCA information */
 150         query_mca();
 151
 152         /* Query Intel SpeedStep (IST) information */
 153         query_ist();
 154
 155         /* Query APM information */
 156 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
 157         query_apm_bios();
 158 #endif
 159
 160         /* Query EDD information */
 161 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
 162         query_edd();
 163 #endif
 164
 165         /* Set the video mode */
 166         set_video();
 167
 168         /* Parse command line for 'quiet' and pass it to decompressor. */
 169         if (cmdline_find_option_bool("quiet"))
 170                 boot_params.hdr.loadflags |= QUIET_FLAG;
 171
 172         /* Do the last things and invoke protected mode */
 173         go_to_protected_mode();
 174 }