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path: root/pcr/grub-legacy/intelmac.patch
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--- grub-0.97.orig/stage2/asm.S	2004-06-19 18:55:22.000000000 +0200
+++ grub-0.97/stage2/asm.S	2006-04-21 11:10:52.000000000 +0200
@@ -1651,7 +1651,29 @@
 	jnz	3f
 	ret
 
-3:	/* use keyboard controller */
+3:	/*
+	 * try to switch gateA20 using PORT92, the "Fast A20 and Init"
+	 * register
+	*/
+	mov $0x92, %dx
+	inb %dx, %al
+	/* skip the port92 code if it's unimplemented (read returns 0xff) */
+	cmpb $0xff, %al
+	jz 6f
+	
+	/* set or clear bit1, the ALT_A20_GATE bit */
+	movb 4(%esp), %ah
+	testb %ah, %ah
+	jz 4f
+	orb $2, %al
+	jmp 5f
+4:	and $0xfd, %al
+	
+	/* clear the INIT_NOW bit don't accidently reset the machine */
+5:	and $0xfe, %al
+	outb %al, %dx
+	
+6:	/* use keyboard controller */
 	pushl	%eax
 
 	call    gloop1
@@ -1661,9 +1683,12 @@
 
 gloopint1:
 	inb	$K_STATUS
+	cmpb	$0xff, %al
+	jz	gloopint1_done
 	andb	$K_IBUF_FUL, %al
 	jnz	gloopint1
 
+gloopint1_done:	
 	movb	$KB_OUTPUT_MASK, %al
 	cmpb	$0, 0x8(%esp)
 	jz	gdoit
@@ -1684,6 +1709,8 @@
 
 gloop1:
 	inb	$K_STATUS
+	cmpb	$0xff, %al
+	jz	gloop2ret
 	andb	$K_IBUF_FUL, %al
 	jnz	gloop1
 
@@ -1991,6 +2018,11 @@
 ENTRY(console_getkey)
 	push	%ebp
 
+wait_for_key:
+	call	EXT_C(console_checkkey)
+	incl	%eax
+	jz	wait_for_key
+	
 	call	EXT_C(prot_to_real)
 	.code16