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Annotation of kernel/machdep/i386/start.s, revision 1.1

1.1     ! root        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: /*
        !            26:  * Copyright (c) 1992 NeXT Computer, Inc.
        !            27:  *
        !            28:  * Kernel startup routine.
        !            29:  *
        !            30:  * HISTORY
        !            31:  *
        !            32:  * 29 August 1992 ? at NeXT
        !            33:  *     Created.
        !            34:  */
        !            35:  
        !            36: #import <architecture/i386/asm_help.h>
        !            37: 
        !            38: #import <assym.h>
        !            39: 
        !            40:        TEXT
        !            41:        /*
        !            42:         * Kernel entry point.
        !            43:         * Control is transferred here
        !            44:         * from the boot loader.  Machine
        !            45:         * is in protected mode, with paging
        !            46:         * turned off.
        !            47:         */
        !            48: LEAF(_start, 0)
        !            49: 
        !            50: // BIOS/DOS hack                       // this says don''t test memory
        !            51: //     movw    $0x1234, %ax            // on reboot/reset
        !            52: //     movw    %ax, 0x472              // pretty obscure
        !            53: // BIOS/DOS hack
        !            54:        cld
        !            55: 
        !            56:        // Initialize GDT & IDT
        !            57:        call    _gdt_init
        !            58:        call    _idt_init
        !            59: 
        !            60:        // switch to new GDT
        !            61:        ljmp    $ LCODESEL,$start1
        !            62: 
        !            63:        /*
        !            64:         * The GDT and IDT descriptors
        !            65:         * can't be defined in C due to
        !            66:         * alignment problems.
        !            67:         */     
        !            68:        DATA
        !            69:        .align  3
        !            70: EXPORT(_gdt_limit)
        !            71:        .word   0
        !            72: EXPORT(_gdt_base)
        !            73:        .long   0
        !            74: 
        !            75:        .align  3
        !            76: EXPORT(_idt_limit)
        !            77:        .word   0
        !            78: EXPORT(_idt_base)
        !            79:        .long   0
        !            80:        
        !            81:        TEXT    
        !            82:        /*
        !            83:         * Running off our GDT
        !            84:         */
        !            85: start1:
        !            86:        // switch to new GDT
        !            87:        mov     $ LDATASEL,%ax  
        !            88:        mov     %ax,%ds
        !            89:        mov     %ax,%es
        !            90:        mov     %ax,%fs
        !            91:        mov     %ax,%gs
        !            92:        mov     %ax,%ss
        !            93: 
        !            94:        /*
        !            95:         * Low level
        !            96:         * initialization.
        !            97:         * Size memory, set vm_page_size,
        !            98:         * setup kernel pmap and enable paging.
        !            99:         */
        !           100:        call    _i386_init
        !           101: 
        !           102:        /*
        !           103:         * Paging is now enabled.
        !           104:         * Start using the kernel
        !           105:         * segments.
        !           106:         */
        !           107:        ljmp    $ KCSSEL,$vstart
        !           108:        
        !           109: vstart:
        !           110:        mov     $ KDSSEL,%ax
        !           111:        mov     %ax,%ds
        !           112:        mov     %ax,%es
        !           113:        mov     %ax,%ss
        !           114: 
        !           115:        // High level initialization
        !           116:        call    _startup_early
        !           117:        call    _setup_main
        !           118: 
        !           119:        // Task switch to the first thread.
        !           120:        push    %eax
        !           121:        call    _start_initial_context
        !           122:        // NOTREACHED
        !           123:        hlt

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