patch-2.1.23 linux/arch/i386/kernel/trampoline.S

• Lines: 182
• Date: Sun Jan 26 12:07:04 1997
• Orig file: v2.1.22/linux/arch/i386/kernel/trampoline.S
• Orig date: Thu Dec 12 19:36:58 1996

diff -u --recursive --new-file v2.1.22/linux/arch/i386/kernel/trampoline.S linux/arch/i386/kernel/trampoline.S
@@ -1,86 +1,107 @@
-!
-!	Trampoline.S	Derived from Setup.S by Linus Torvalds
-!
-!	Entry: CS:IP point to the start of our code, we are 
-!	in real mode with no stack, but the rest of the 
-!	trampoline page to make our stack and everything else
-!	is a mystery.
-!
-!	In fact we don't actually need a stack so we don't
-!	set one up.
-!
-!	We jump into the boot/compressed/head.S code. So you'd
-!	better be running a compressed kernel image or you
-!	won't get very far.
-!
-#define __ASSEMBLY__
+/*
+ *
+ *	Trampoline.S	Derived from Setup.S by Linus Torvalds
+ *
+ *	4 Jan 1997 Michael Chastain: changed to gnu as.
+ *
+ *	Entry: CS:IP point to the start of our code, we are 
+ *	in real mode with no stack, but the rest of the 
+ *	trampoline page to make our stack and everything else
+ *	is a mystery.
+ *
+ *	In fact we don't actually need a stack so we don't
+ *	set one up.
+ *
+ *	We jump into the boot/compressed/head.S code. So you'd
+ *	better be running a compressed kernel image or you
+ *	won't get very far.
+ *
+ *	On entry to trampoline_data, the processor is in real mode
+ *	with 16-bit addressing and 16-bit data.  CS has some value
+ *	and IP is zero.  Thus, data addresses need to be absolute
+ *	(no relocation) and are taken with regard to r_base.
+ *
+ *	On the transition to protected mode, this page appears at
+ *	address 8192, so protected mode addresses are with regard
+ *	to p_base.
+ *
+ *	If you work on this file, check the object module with objdump
+ *	--full-contents --reloc to make sure there are no relocation
+ *	entries.
+ */
+
+#include <linux/linkage.h>
 #include <asm/segment.h>
 
-.text
-	extrn startup32
+.data
+
+.code16
+
+ENTRY(trampoline_data)
+r_base = .
+p_base = . - 8192
+
+	mov	%cs, %ax	# Code and data in the same place
+	mov	%ax, %ds
+
+	mov	%ax, %cx	# Pass stack info to the 32bit boot
+	shl	$4, %cx		# Segment -> Offset
+	add	$4096, %cx	# End of page is wanted
+
+	mov	$1, %bx		# Flag an SMP trampoline
+	cli			# We should be safe anyway
+
+	movl	$0xA5A5A5A5, trampoline_data - r_base
+				# write marker for master knows we're running
+
+	lidt	idt_48 - r_base	# load idt with 0, 0
+	lgdt	gdt_48 - r_base	# load gdt with whatever is appropriate
 
-entry start
-start:
-!	nop
-!	jmp start	! 	Test
-	mov ax,cs	!	Code and data in the same place
-	mov ds,ax	!
-	mov cx,ax	!	Pass stack info to the 32bit boot
-	add cx,cx
-	add cx,cx
-	add cx,cx
-	add cx,cx	!	Segment -> Offset
-	add cx, #4096   !	End of page is wanted
-	mov     bx,#1	!	Flag an SMP trampoline
-	cli		!	We should be safe anyway
-
-	lidt	idt_48	!	load idt with 0,0
-	lgdt	gdt_48	!	load gdt with whatever is appropriate
-
-	xor	ax,ax	
-	inc	ax	!	protected mode (PE) bit
-	lmsw	ax	!	Into protected mode
+	xor	%ax, %ax
+	inc	%ax		# protected mode (PE) bit
+	lmsw	%ax		# into protected mode
 	jmp	flush_instr
 flush_instr:
-	jmpi	8192+startup32,KERNEL_CS	!	Jump to the 32bit trampoline code
-!	jmpi	0x100000,KERNEL_CS		!	Jump into the 32bit startup
-!	.byte   0x66,0x67			!	32bit
-!	.byte	0xea,0x00,0x00,0x10,0x00,0x10,0x00	!jmpi	.0x100000,KERNEL_CS
+	ljmp	$KERNEL_CS, $0x00100000
+				# jump to startup_32
 
+idt_48:
+	.word	0			# idt limit = 0
+	.word	0, 0			# idt base = 0L
+
+gdt_48:
+	.word	0x0800			# gdt limit = 2048, 256 GDT entries
+	.word	gdt - p_base, 0x0	# gdt base = gdt (first SMP CPU)
+					# we load the others with first table
+					# saves rewriting gdt_48 for each
 gdt:
-	.word	0,0,0,0		! dummy
+	.word	0, 0, 0, 0	# dummy
 
-	.word	0,0,0,0		! unused
+	.word	0, 0, 0, 0	# unused
 
-!walken modif
-        .word   0xFFFF          ! 4Gb - (0x100000*0x1000 = 4Gb)
-        .word   0x0000          ! base address=0
-        .word   0x9A00          ! code read/exec
-        .word   0x00CF          ! granularity=4096, 386 (+5th nibble of limit)
-
-        .word   0xFFFF          ! 4Gb - (0x100000*0x1000 = 4Gb)
-        .word   0x0000          ! base address=0
-        .word   0x9200          ! data read/write
-        .word   0x00CF          ! granularity=4096, 386 (+5th nibble of limit)
-!walken modif
-
-!	.word	0x07FF		! 8Mb - limit=2047 (2048*4096=8Mb)
-!	.word	0x0000		! base address=0
-!	.word	0x9A00		! code read/exec
-!	.word	0x00C0		! granularity=4096, 386
-
-!	.word	0x07FF		! 8Mb - limit=2047 (2048*4096=8Mb)
-!	.word	0x0000		! base address=0
-!	.word	0x9200		! data read/write
-!	.word	0x00C0		! granularity=4096, 386
+# walken modif
 
-idt_48:
-	.word	0			! idt limit=0
-	.word	0,0			! idt base=0L
+	.word	0xFFFF		# 4 Gb - (0x100000*0x1000 = 4Gb)
+	.word	0x0000		# base address = 0
+	.word	0x9A00		# code read / exec
+	.word	0x00CF		# granularity = 4096, 386 (+5th nibble of limit)
 
-gdt_48:
-	.word	0x800		! gdt limit=2048, 256 GDT entries
-	.word	8192+gdt,0x0	! gdt base = 8192+gdt (first SMP CPU)
-				! we load the others with the first table
-				! saves rewriting gdt_48 for each
+	.word	0xFFFF		# 4 Gb - (0x100000*0x1000 = 4Gb)
+	.word	0x0000		# base address = 0
+	.word	0x9200		# data read / write
+	.word	0x00CF		# granularity = 4096, 386 (+5th nibble of limit)
+
+# walken modif
+
+#	.word	0x07FF		# 8 Mb - limit = 2047 (2048 * 4096 = 8 Mb)
+#	.word	0x0000		# base address = 0
+#	.word	0x9A00		# code read / exec
+#	.word	0x00C0		# granularity = 4096, 386
+
+#	.word	0x07FF		# 8 Mb - limit = 2047 (2048 * 4096 = 8 Mb)
+#	.word	0x0000		# base address = 0
+#	.word	0x9200		# data read / write
+#	.word	0x00C0		# granularity = 4096, 386
 
+.globl SYMBOL_NAME(trampoline_end)
+SYMBOL_NAME_LABEL(trampoline_end)