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startprog.S revision 1.4 
      1 /*	$NetBSD: startprog.S,v 1.4 2016/12/04 08:21:08 maxv Exp $	*/
      2 
      3 /*
      4  * Ported to boot 386BSD by Julian Elischer (julian (at) tfs.com) Sept 1992
      5  *
      6  * Mach Operating System
      7  * Copyright (c) 1992, 1991 Carnegie Mellon University
      8  * All Rights Reserved.
      9  *
     10  * Permission to use, copy, modify and distribute this software and its
     11  * documentation is hereby granted, provided that both the copyright
     12  * notice and this permission notice appear in all copies of the
     13  * software, derivative works or modified versions, and any portions
     14  * thereof, and that both notices appear in supporting documentation.
     15  *
     16  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     17  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     18  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     19  *
     20  * Carnegie Mellon requests users of this software to return to
     21  *
     22  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     23  *  School of Computer Science
     24  *  Carnegie Mellon University
     25  *  Pittsburgh PA 15213-3890
     26  *
     27  * any improvements or extensions that they make and grant Carnegie Mellon
     28  * the rights to redistribute these changes.
     29  */
     30 
     31 /*
     32  *   Copyright 1988, 1989, 1990, 1991, 1992
     33  *    by Intel Corporation, Santa Clara, California.
     34  *
     35  *                 All Rights Reserved
     36  *
     37  * Permission to use, copy, modify, and distribute this software and
     38  * its documentation for any purpose and without fee is hereby
     39  * granted, provided that the above copyright notice appears in all
     40  * copies and that both the copyright notice and this permission notice
     41  * appear in supporting documentation, and that the name of Intel
     42  * not be used in advertising or publicity pertaining to distribution
     43  * of the software without specific, written prior permission.
     44  *
     45  * INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
     46  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
     47  * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
     48  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
     49  * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
     50  * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
     51  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     52  */
     53 
     54 #include <machine/asm.h>
     55 
     56 /*
     57  * Starts program in protected mode / flat space with given stackframe.
     58  * Needs global variables flatcodeseg and flatdataseg (gdt offsets).
     59  */
     60 
     61 /*
     62  * startprog(phyaddr, argc, argv, stack)
     63  *	start the program on protected mode where phyaddr is the entry point
     64  */
     65 ENTRY(startprog)
     66 	pushl	%ebp
     67 	movl	%esp,%ebp
     68 
     69 	/* Prepare a new stack */
     70 	movl	$flatdataseg,%ebx
     71 	movw	%bx,%es		/* for arg copy */
     72 	movl	20(%ebp),%eax	/* stack */
     73 	subl	$4,%eax
     74 	movl	%eax,%edi
     75 
     76 	/* Push some number of args onto the stack */
     77 	movl	12(%ebp),%ecx	/* argc */
     78 	movl	%ecx,%eax
     79 	decl	%eax
     80 	shl	$2,%eax
     81 	addl	16(%ebp),%eax	/* ptr to last arg */
     82 	movl	%eax,%esi
     83 
     84 	std			/* backwards */
     85 	rep
     86 	movsl			/* copy %ds:(%esi) -> %es:(%edi) */
     87 
     88 	cld
     89 
     90 	movl	8(%ebp),%ecx	/* entry */
     91 
     92 	/* Set new stack pointer (movsl decd sp 1 more -> dummy return address) */
     93 	movw	%bx,%ss
     94 	movl	%edi,%esp
     95 
     96 	/* Push on our entry address */
     97 	movl	$flatcodeseg,%ebx
     98 	pushl	%ebx			/* code segment */
     99 	pushl	%ecx			/* phyaddr */
    100 
    101 	/* Convert over the other data segs */
    102 	movl	$flatdataseg,%ebx
    103 	mov	%bx,%ds
    104 	mov	%bx,%es
    105 
    106 	/* Jump to phyaddr, with the new code segment */
    107 	lret
    108 
    109