source: mainline/arch/ia32/src/boot/memmap.S@ 6401f79

/*
 * Copyright (C) 2005 Josef Cejka
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


#include <arch/boot/memmapasm.h>

E820_RECORD_SIZE = MEMMAP_E820_RECORD_SIZE
E820_MAX_RECORDS = MEMMAP_E820_MAX_RECORDS
E820_SMAP = 0x534d4150

.global memmap_arch_init
.global e801memorysize

.code16
.section K_TEXT_START_2

memmap_arch_init:

e820begin:
        xorl    %ebx,%ebx       # during first call, ebx must be 0
        movw    %bx,%ds
        movw    %bx,%es
        movw    $e820table_boot,%di
        movb    $E820_MAX_RECORDS,e820counter_boot
e820loop:       
        movl    $E820_SMAP,%edx         # control sequence "SMAP"

        movl    $0x0000e820,%eax        # service
        movl    $E820_RECORD_SIZE,%ecx
        int     $0x15
        jc      e820err
        
        cmpl    $E820_SMAP,%eax         # verifying BIOS
        jne     e820err

        cmpl    $E820_RECORD_SIZE,%ecx
        jne     e820err                 # bad record size - bug in bios
        
        movw    %di,%ax         # next record
        addw    $E820_RECORD_SIZE,%ax
        movw    %ax,%di
                
        decb    e820counter_boot # buffer is full
        jz      e820end
        
        cmpl    $0,%ebx 
        jne     e820loop
        
e820end:
        movb    $E820_MAX_RECORDS,%al
        subb    e820counter_boot,%al
        movb    %al,e820counter_boot # store # of valid entries in e820counter

        jmp     e801begin

e820err:
        movb    $0,e820counter_boot

# method e801 - get size of memory

e801begin:
        xorw    %dx,%dx
        xorw    %cx,%cx
        xorw    %bx,%bx
        movw    $0xe801,%ax
        stc
        int     $0x15
        
        jc      e801end
        
                        # fix problem with some BIOSes which use ax:bx rather than cx:dx
        testw   %cx,%cx
        jnz     e801cxdx
        testw   %dx,%dx
        jnz     e801cxdx

        movw    %ax,%cx
        movw    %bx,%dx
        
e801cxdx:
        andl    $0xffff,%edx
        shll    $6,%edx
        andl    $0xffff,%ecx
        addl    %ecx,%edx
        addl    $0x0400,%edx  # add lower 1 MB - it's not included by e801 method
        movl    %edx,e801memorysize
e801end:
        ret

        #memory size in 1 kb chunks
e801memorysize:
        .long   0