[apple/boot.git] / i386 / boot2 / boot2.s

/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
 * Reserved.  This file contains Original Code and/or Modifications of
 * Original Code as defined in and that are subject to the Apple Public
 * Source License Version 1.1 (the "License").  You may not use this file
 * except in compliance with the License.  Please obtain a copy of the
 * License at http://www.apple.com/publicsource and read it before using
 * this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1990 Carnegie-Mellon University
 * Copyright (c) 1989 Carnegie-Mellon University
 * All rights reserved.  The CMU software License Agreement specifies
 * the terms and conditions for use and redistribution.
 */

/*
 * boot2() -- second stage boot.
 *
 * This function must be located at 0:BOOTER_ADDR and will be called
 * by boot1 or by NBP.
 */

#include <architecture/i386/asm_help.h>
#include "memory.h"

#define data32  .byte 0x66
#define retf    .byte 0xcb

    .file "boot2.s"

    .data

EXPORT(_chainbootdev)  .byte 0x80
EXPORT(_chainbootflag) .byte 0x00

.text

# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Booter entry point. Called by boot1 or by the NBP.
# This routine must be the first in the TEXT segment.
#
# Arguments:
#   DX    = Boot device
#
# Returns:
#
LABEL(boot2)
    pushl   %ecx                # Save general purpose registers
    pushl   %ebx
    pushl   %ebp
    pushl   %esi
    pushl   %edi
    push    %ds                 # Save DS, ES
    push    %es

    mov     %cs, %ax            # Update segment registers.
    mov     %ax, %ds            # Set DS and ES to match CS
    mov     %ax, %es

    data32
    call    __switch_stack      # Switch to new stack

    data32
    call    __real_to_prot      # Enter protected mode.

    # We are now in 32-bit protected mode.
    # Transfer execution to C by calling boot().

    pushl   %edx                # bootdev
    call    _boot

    testb   $0xff, _chainbootflag
    jnz     start_chain_boot    # Jump to a foreign booter

    call    __prot_to_real      # Back to real mode.

    data32
    call    __switch_stack      # Restore original stack
    
    pop     %es                 # Restore original ES and DS
    pop     %ds
    popl    %edi                # Restore all general purpose registers
    popl    %esi                # except EAX.
    popl    %ebp
    popl    %ebx
    popl    %ecx

    retf                        # Hardcode a far return

start_chain_boot:
    xorl    %edx, %edx
    movb    _chainbootdev, %dl  # Setup DL with the BIOS device number

    call    __prot_to_real      # Back to real mode.

    data32
    call    __switch_stack      # Restore original stack
    
    pop     %es                 # Restore original ES and DS
    pop     %ds
    popl    %edi                # Restore all general purpose registers
    popl    %esi                # except EAX.
    popl    %ebp
    popl    %ebx
    popl    %ecx

    data32
    ljmp    $0, $0x7c00         # Jump to boot code already in memory
Commit	Line	Data
14c7c974 A	1	/*
	2	* Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
	6	* Portions Copyright (c) 1999 Apple Computer, Inc. All Rights
	7	* Reserved. This file contains Original Code and/or Modifications of
	8	* Original Code as defined in and that are subject to the Apple Public
	9	* Source License Version 1.1 (the "License"). You may not use this file
	10	* except in compliance with the License. Please obtain a copy of the
	11	* License at http://www.apple.com/publicsource and read it before using
	12	* this file.
	13	*
	14	* The Original Code and all software distributed under the License are
	15	* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	16	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	17	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	18	* FITNESS FOR A PARTICULAR PURPOSE OR NON- INFRINGEMENT. Please see the
	19	* License for the specific language governing rights and limitations
	20	* under the License.
	21	*
	22	* @APPLE_LICENSE_HEADER_END@
	23	*/
	24	/*
	25	* Mach Operating System
	26	* Copyright (c) 1990 Carnegie-Mellon University
	27	* Copyright (c) 1989 Carnegie-Mellon University
	28	* All rights reserved. The CMU software License Agreement specifies
	29	* the terms and conditions for use and redistribution.
	30	*/
	31
	32	/*
	33	* boot2() -- second stage boot.
	34	*
	35	* This function must be located at 0:BOOTER_ADDR and will be called
	36	* by boot1 or by NBP.
	37	*/
	38
	39	#include <architecture/i386/asm_help.h>
	40	#include "memory.h"
	41
	42	#define data32 .byte 0x66
	43	#define retf .byte 0xcb
	44
14c7c974 A	45	.file "boot2.s"
14c7c974 A	46
75b89a82 A	47	.data
	48
	49	EXPORT(_chainbootdev) .byte 0x80
	50	EXPORT(_chainbootflag) .byte 0x00
	51
14c7c974 A	52	.text
	53
	54	# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
	55	# Booter entry point. Called by boot1 or by the NBP.
	56	# This routine must be the first in the TEXT segment.
	57	#
	58	# Arguments:
	59	# DX = Boot device
	60	#
	61	# Returns:
	62	#
	63	LABEL(boot2)
	64	pushl %ecx # Save general purpose registers
	65	pushl %ebx
	66	pushl %ebp
	67	pushl %esi
	68	pushl %edi
	69	push %ds # Save DS, ES
	70	push %es
	71
	72	mov %cs, %ax # Update segment registers.
	73	mov %ax, %ds # Set DS and ES to match CS
	74	mov %ax, %es
	75
	76	data32
	77	call __switch_stack # Switch to new stack
	78
	79	data32
	80	call __real_to_prot # Enter protected mode.
	81
	82	# We are now in 32-bit protected mode.
	83	# Transfer execution to C by calling boot().
	84
	85	pushl %edx # bootdev
	86	call _boot
	87
75b89a82 A	88	testb $0xff, _chainbootflag
	89	jnz start_chain_boot # Jump to a foreign booter
	90
14c7c974 A	91	call __prot_to_real # Back to real mode.
	92
	93	data32
	94	call __switch_stack # Restore original stack
	95
	96	pop %es # Restore original ES and DS
	97	pop %ds
	98	popl %edi # Restore all general purpose registers
	99	popl %esi # except EAX.
	100	popl %ebp
	101	popl %ebx
	102	popl %ecx
	103
	104	retf # Hardcode a far return
	105
75b89a82 A	106	start_chain_boot:
	107	xorl %edx, %edx
	108	movb _chainbootdev, %dl # Setup DL with the BIOS device number
	109
	110	call __prot_to_real # Back to real mode.
	111
	112	data32
	113	call __switch_stack # Restore original stack
	114
	115	pop %es # Restore original ES and DS
	116	pop %ds
	117	popl %edi # Restore all general purpose registers
	118	popl %esi # except EAX.
	119	popl %ebp
	120	popl %ebx
	121	popl %ecx
	122
	123	data32
	124	ljmp $0, $0x7c00 # Jump to boot code already in memory