release 3.7

https://sourceforge.net/projects/elilo/files/elilo/3.7/

x86_64/rmswitch.S

@@ -0,0 +1,118 @@
+#
+# Switch from protected mode to real mode and jump to setup.S
+# image located at %cx:0.
+#
+# This module must be placed into physical memory at 0:7C00h.
+# EFI has some real mode thunking code at 2000:0h.
+#
+# Processor and non-maskable interrupts should be disabled
+# before control is passed to this module.
+#
+
+.global _start
+
+.code32
+.text
+_start:
+	#
+	# Load identity mapped GDT & real mode IDT.
+	# Add 7C00h to the addresses since this is linked to start
+	# at 0h and it is being placed at 7C00h.
+	#
+
+	lgdt	%cs:gdt_48 + 0x7C00
+	lidt	%cs:idt_48 + 0x7C00
+
+	#
+	# Turn off PG bit in CR0 and set CR3 to zero.
+	#
+
+	movl	%cr0, %eax
+	andl	$0x7FFFFFFF, %eax
+	movl	%eax, %cr0
+
+	xorl	%eax, %eax
+	movl	%eax, %cr3
+
+	#
+	# Reload CS.
+	# Now we add 7B00h because we need to force the segment
+	# address and selector to be the same.
+	#
+
+	.byte	0xEA
+	.long	pm_reload + 0x7B00
+	.word	0x10
+
+pm_reload:
+
+.code16
+
+	#
+	# Reload DS, ES, FS, GS & SS.
+	#
+
+	movw	$0x18, %ax
+	movw	%ax, %ds
+	movw	%ax, %es
+	movw	%ax, %fs
+	movw	%ax, %gs
+	movw	%ax, %ss
+
+	#
+	# Switch to real mode.  Clear PE bit in CR0.
+	#
+
+	movl	%cr0, %eax
+	andl	$0xFFFFFFFE, %eax
+	movl	%eax, %cr0
+
+	#
+	# Reload CS.
+	#
+
+	.byte	0xEA
+	.word	rm_reload + 0x7C00
+	.word	0
+
+rm_reload:
+
+	#
+	# Reload SS & SP.
+	#
+
+	xorw	%ax, %ax
+	movw	%ax, %ss
+	movw	$0x7BFE, %sp
+
+	#
+	# Start running setup.S
+	#
+
+	.byte	0xEA
+	.word	0
+	.word	0x9020
+
+	#
+	# GDT & IDT stuff for switching into real mode.
+	#
+
+gdt:	.word	0, 0, 0, 0		# unused (00h)
+	.word	0, 0, 0, 0		# dummy (08h)
+	.word	0xFFFF, 0x100		# code (10h)
+	.word	0x9A00, 0
+	.word	0xFFFF, 0x180		# data (18h)
+	.word	0x9200, 0
+
+gdt_48:	.word	0x08 * 0x400
+	.long	gdt + 0x7C00
+
+idt_48:	.word	0x400
+	.long	0
+
+	#
+	# Be careful not to exceed 1F0h or the the bootsect.S
+	# parameters will be lost!
+	#
+
+.end