freeldr/freeldr/mb.S

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 1999, 2000, 2001  Brian Palmer  <brianp@sginet.com>
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20         .text
  21         .code16
  22
  23 #define ASM
  24 #include "asmcode.h"
  25 #include "multiboot.h"
  26
  27         /*
  28      * Here we assume the kernel is loaded at 1mb
  29      * This boots the kernel
  30          */
  31         .code32
  32 EXTERN(_boot_reactos)
  33         call    switch_to_real
  34         .code16
  35
  36     /* Save cursor position */
  37         movw    $3,%ax          //! Reset video mode
  38         int     $0x10
  39
  40
  41         movb    $10,%bl
  42         movb    $12,%ah
  43         int     $0x10
  44
  45         movw    $0x1112,%ax             // Use 8x8 font
  46         xorb    %bl,%bl
  47         int     $0x10
  48         movw    $0x1200,%ax             // Use alternate print screen
  49         movb    $0x20,%bl
  50         int     $0x10
  51         movb    $1,%ah                  // Define cursor (scan lines 6 to 7)
  52         movw    $0x0607,%cx
  53         int     $0x10
  54
  55         movb    $1,%ah
  56         movw    $0x600,%cx
  57         int     $0x10
  58
  59         movb    $6,%ah                  // Scroll active page up
  60         movb    $0x32,%al               // Clear 25 lines
  61         movw    $0,%cx                  // Upper left of scroll
  62         movw    $0x314F,%dx             // Lower right of scroll
  63         movb    $(1*0x10+1),%bh // Use normal attribute on blanked line
  64         int             $0x10                   // Video-IO
  65
  66
  67         movw    $0,%dx
  68         movb    $0,%dh
  69
  70         movb    $2,%ah
  71         movb    $0,%bh
  72         int             $0x10
  73
  74         movw    $0,%dx
  75         movb    $0,%dh
  76
  77         movb    $2,%ah
  78         movb    $0,%bh
  79         int             $0x10
  80
  81         call    _multi_boot
  82
  83         // Should never get here
  84         cli
  85         hlt
  86
  87
  88         /*
  89          * After you have setup the _mb_header and _mb_info structures
  90          * then call this routine to transfer control to the kernel.
  91          * This routine must be entered in 16-bit mode.
  92          */
  93         .code16
  94 EXTERN(_multi_boot)
  95
  96         cli
  97
  98         /*
  99          * Setup various variables
 100          */
 101         movw    %ds,%bx
 102         movzwl  %bx,%eax
 103         shll    $4,%eax
 104         addl    %eax,kernel_gdtbase
 105
 106         /*
 107          * Load the absolute address of the multiboot information structure
 108          */
 109         movl    $_mb_info,%ebx
 110
 111         /*
 112          * load gdt
 113          */
 114         lgdt    kernel_gdtptr
 115
 116         /*
 117          * Enter pmode and clear prefetch queue
 118          */
 119         movl    %cr0,%eax
 120         orl             $0x10001,%eax
 121         movl    %eax,%cr0
 122         jmp             next
 123 next:
 124         /*
 125          * NOTE: This must be position independant (no references to
 126          * non absolute variables)
 127          */
 128
 129         /*
 130          * Initalize segment registers
 131          */
 132         movw    $KERNEL_DS,%ax
 133         movw    %ax,%ds
 134         movw    %ax,%ss
 135         movw    %ax,%es
 136         movw    %ax,%fs
 137         movw    %ax,%gs
 138
 139         /*
 140          * Initalize eflags
 141          */
 142         pushl   $0
 143         popfl
 144
 145         /*
 146          * Load the multiboot magic value into eax
 147          */
 148         movl    $0x2badb002,%eax
 149
 150         /*
 151          * Jump to start of 32 bit code at 0xc0000000 + 0x1000
 152          */
 153
 154         pushl   $KERNEL_CS
 155         pushl   _mb_entry_addr
 156         lretl
 157
 158         //ljmpl $KERNEL_CS,$(0x0200000+0x1000)
 159         //ljmpl $KERNEL_CS,(_mb_entry_addr)
 160         //ljmpl $KERNEL_CS,$(KERNEL_BASE+0x1000)
 161
 162
 163         .p2align        2       /* force 4-byte alignment */
 164 kernel_gdt:
 165         .word 0               // Zero descriptor
 166         .word 0
 167         .word 0
 168         .word 0
 169
 170         .word 0xffff          // Kernel code descriptor
 171         .word 0x0000          //
 172         .word 0x9a00          // base 0h limit 4gb
 173         .word 0x00cf
 174
 175         .word 0xffff          // Kernel data descriptor
 176         .word 0x0000          //
 177         .word 0x9200          // base 0h limit 4gb
 178         .word 0x00cf
 179
 180 kernel_gdtptr:
 181         .word   (3*8)-1                 /* Limit */
 182 kernel_gdtbase:
 183         .long   kernel_gdt                              /* Base Address */
 184
 185
 186 EXTERN(_mb_header)
 187 _mb_magic:
 188         .long   0               // unsigned long magic;
 189 _mb_flags:
 190         .long   0               // unsigned long flags;
 191 _mb_checksum:
 192         .long   0               // unsigned long checksum;
 193 _mb_header_addr:
 194         .long   0               // unsigned long header_addr;
 195 _mb_load_addr:
 196         .long   0               // unsigned long load_addr;
 197 _mb_load_end_addr:
 198         .long   0               // unsigned long load_end_addr;
 199 _mb_bss_end_addr:
 200         .long   0               // unsigned long bss_end_addr;
 201 _mb_entry_addr:
 202         .long   0               // unsigned long entry_addr;
 203
 204         //
 205         // Boot information structure
 206         //
 207
 208 EXTERN(_mb_info)
 209 _multiboot_flags:
 210         .long   0
 211 _multiboot_mem_lower:
 212         .long   0
 213 _multiboot_mem_upper:
 214         .long   0
 215 _multiboot_boot_device:
 216         .long   0
 217 _multiboot_cmdline:
 218         .long   0
 219 _multiboot_mods_count:
 220         .long   0
 221 _multiboot_mods_addr:
 222         .long   0
 223 _multiboot_syms:
 224         .rept   12
 225         .byte   0
 226         .endr
 227 _multiboot_mmap_length:
 228         .long   0
 229 _multiboot_mmap_addr:
 230         .long   0
 231 _multiboot_drives_count:
 232         .long   0
 233 _multiboot_drives_addr:
 234         .long   0
 235 _multiboot_config_table:
 236         .long   0
 237 _multiboot_boot_loader_name:
 238         .long   0
 239 _multiboot_apm_table:
 240         .long   0
 241
 242 EXTERN(_multiboot_modules)
 243         .rept   (64 * /*multiboot_module_size*/ 16)
 244         .byte   0
 245         .endr
 246 EXTERN(_multiboot_module_strings)
 247         .rept   (64*256)
 248         .byte   0
 249         .endr
 250
 251 _multiboot_address_range_descriptor_size:
 252         .long   0
 253
 254 _multiboot_address_ranges:
 255         .rept   (64 * /*multiboot_address_range_size*/24)
 256         .byte   0
 257         .endr
 258
 259 EXTERN(_multiboot_kernel_cmdline)
 260         .rept   255
 261         .byte   0
 262         .endr