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2 pj 1
/* Project:     OSLib
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 * Description: The OS Construction Kit
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 * Date:                1.6.2000
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 * Idea by:             Luca Abeni & Gerardo Lamastra
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 *
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 * OSLib is an SO project aimed at developing a common, easy-to-use
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 * low-level infrastructure for developing OS kernels and Embedded
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 * Applications; it partially derives from the HARTIK project but it
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 * currently is independently developed.
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 *
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 * OSLib is distributed under GPL License, and some of its code has
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 * been derived from the Linux kernel source; also some important
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 * ideas come from studying the DJGPP go32 extender.
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 *
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 * We acknowledge the Linux Community, Free Software Foundation,
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 * D.J. Delorie and all the other developers who believe in the
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 * freedom of software and ideas.
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 *
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 * For legalese, check out the included GPL license.
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 */
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/* The first things to do when an OSLib application starts :	*/
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/* Set up segment registers & stack; then execute startup code	*/
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/* When the application returns the gate-jmp make us return to	*/
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/* RM through X interface!					*/
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/* Use X standard GDT selectors */
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#include <ll/i386/sel.h>
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#include <ll/i386/linkage.h>
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#include <ll/i386/defs.h>
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#include <ll/i386/mb-hdr.h>
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/* #define __DEBUG__ */
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#ifdef __LINUX__ /* ELF mode */
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#define MULTIBOOT_FLAGS (MULTIBOOT_MEMORY_INFO)
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#else /* else it is COFF! */
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#define MULTIBOOT_FLAGS (MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE)
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#endif
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.extern SYMBOL_NAME(_startup)
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.extern SYMBOL_NAME(_stkbase)
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.extern SYMBOL_NAME(_stktop)
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.extern SYMBOL_NAME(halt)
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.data
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ASMFILE(X0)
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.globl SYMBOL_NAME(IDT)
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.globl SYMBOL_NAME(GDT_base)
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.globl SYMBOL_NAME(mb_signature)
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.globl SYMBOL_NAME(mbi)
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/* GDT Definition */
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GDT:
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.word	0,0,0,0		/* X_NULL_SEL */
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.word	0,0,0,0		/* X_DATA16_SEL */
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.word	0,0,0,0		/* X_CODE16_SEL */
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.word	0,0,0,0		/* X_CODE32_SEL */
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			/* X_RM_BACK_GATE */
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rmBckGateFix1:		/* X_FLATCODE_SEL */
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.word	0
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.word	X_FLATCODE_SEL
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.word	0x8C00
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rmBckGateFix2:
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.word	0
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.word	0,0,0,0		/* X_PM_BACK_GATE */
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.word	0xFFFF		/* X_FLATDATA_SEL */
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.word	0
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.word	0x9200
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.word	0x00CF
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.word	0xFFFF		/* X_FLATCODE_SEL */
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.word	0
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.word	0x9A00
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.word	0x00CF
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.word	0,0,0,0		/* X_CALLBIOS_SEL */
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.word	0,0,0,0		/* X_CALLBIOS_GATE */
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.word	0,0,0,0		/* X_VM86_TSS */
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.word	0,0,0,0		/* X_MAIN_TSS */
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	.fill 256 - 12,8,0
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GDT_descr:
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.word 256*8-1
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SYMBOL_NAME_LABEL(GDT_base)
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.long GDT
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IDT_descr:
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	.word 256*8-1		# idt contains 256 entries
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	.long SYMBOL_NAME(IDT)
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/* MultiBoot Data Stuff definition */
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SYMBOL_NAME_LABEL(mb_signature) .long 0
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SYMBOL_NAME_LABEL(mbi) .long 0
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.bss		/* This MUST be in the BSS !!! */
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/* IDT definition */
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SYMBOL_NAME_LABEL(IDT)
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	.fill 256,8,0		# idt is uninitialized
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/* Protected mode stack */
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base:
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.space 	8192,0
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tos:
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.text
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.globl	SYMBOL_NAME(_start)
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.globl SYMBOL_NAME(__exit)
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/*.globl	SYMBOL_NAME(start)*/
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.globl start
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SYMBOL_NAME_LABEL(_start)
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/*SYMBOL_NAME_LABEL(start)*/
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start:
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.align		8
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/*start:*/
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		jmp	boot_entry
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		/*
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		Here we go with the multiboot header...
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		---------------------------------------
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		*/
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.align		8
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boot_hdr:
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.align		8
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		.long	MULTIBOOT_MAGIC
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		.long   MULTIBOOT_FLAGS
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		/* Checksum */
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		.long	-(MULTIBOOT_MAGIC+MULTIBOOT_FLAGS)
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#ifndef __LINUX__ /* COFF mode */
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		.long	boot_hdr
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/*		.long	SYMBOL_NAME(start)*/
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		.long   start
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		.long	_edata
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		.long	_end
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		.long	boot_entry
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#endif
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boot_entry:	/* Just a brief debug check */
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		#ifdef __DEBUG__
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		/* A Brown 1 should appear... */
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		    movl	$0xB8000,%edi
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		    addl	$158,%edi
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		    movb	$'1',%gs:0(%edi)
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		    incl	%edi
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		    movb	$6,%gs:0(%edi)
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		#endif
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		/*
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		 * Hopefully if it gets here, CS & DS are
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		 * Correctly set for FLAT LINEAR mode
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		 */
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		/* Test if GDT is usable */
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		movl	%gs:0(%ebx),%ecx
40 pj 156
		andl	$0x0200,%ecx	/* MB_INFO_BOOT_LOADER_NAME */
2 pj 157
movl	$0xB8000,%edi
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addl	$150,%edi
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movb	$'1',%gs:0(%edi)
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incl	%edi
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movb	$6,%gs:0(%edi)
40 pj 162
		jz	GDT_is_not_OK
2 pj 163
incl	%edi
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movb	$'2',%gs:0(%edi)
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incl	%edi
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movb	$6,%gs:0(%edi)
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40 pj 168
		movl	%gs:64(%ebx), %ebp /* Name Address... */
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		cmpb	$'X', %gs:0(%ebp)
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		je	GDT_is_OK
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GDT_is_not_OK:
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		/*
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		 * Fix the X_RM_BACK_GATE with the address of halt()
174
		*/
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/* Now I test if the check mechanism is OK... */
2 pj 177
		movl	$SYMBOL_NAME(halt),%eax
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		movw	%ax,%gs:rmBckGateFix1
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		shrl	$16,%eax
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		movw	%ax,%gs:rmBckGateFix2
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		/* Load GDT, using the predefined assignment! */
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		lgdt	GDT_descr
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movl	$0xB8000,%edi
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addl	$146,%edi
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movb	$'0',%gs:0(%edi)
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incl	%edi
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movb	$6,%gs:0(%edi)
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GDT_is_OK:	movw	$(X_FLATDATA_SEL),%ax
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		movw	%ax,%ds
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		movw	%ax,%es
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		movw	%ax,%ss
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		movw	%ax,%fs
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		movw	%ax,%gs
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		movl	$tos,%esp
197
		movl	$base,SYMBOL_NAME(_stkbase)
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		movl	$tos,SYMBOL_NAME(_stktop)
199
 
200
		/* Store the MULTIBOOT informations */
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		movl	%eax,SYMBOL_NAME(mb_signature)
202
		movl	%ebx,SYMBOL_NAME(mbi)
203
 
204
		/* Store the X passed GDT address!
205
		 * If GDT is not available is a dummy instruction!
206
		 */
207
		sgdt 	GDT_descr
208
 
209
		/* Now probably is the case to load CS... */
210
		ljmp $X_FLATCODE_SEL, $load_cs
211
 
212
load_cs:
213
		/* Load IDT */
214
		lidt	IDT_descr
215
 
216
		cld
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		call SYMBOL_NAME(_startup)
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219
		/* Well I hope when I reach this
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		   The X_RM_BACK_GATE has been setup correctly
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		   even if the kernel has not been loaded through X!
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		*/
223
		.byte	0x0EA		   /* Direct gate jmp */
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		.long	0
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		.word	X_RM_BACK_GATE
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227
/* Simple function to terminate PM application	*/
228
 
229
/* void __exit(int code)				*/
230
 
231
SYMBOL_NAME_LABEL(__exit)
232
		pushl	%ebp
233
		movl	%esp,%ebp
234
		movl	8(%ebp),%eax
235
		.byte	0x0ea		   /* Direct gate jmp */
236
		.long	0
237
		.word	X_RM_BACK_GATE