From: H. Peter Anvin <hpa@zytor.com>
Date: Mon, 5 Nov 2007 01:50:12 +0000 (-0800)
Subject: x86 setup: add a near jump to serialize %cr0 on 386/486
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=7ed192906a2144ebc8ca2925a85d27b9c5355668;p=deliverable%2Flinux.git

x86 setup: add a near jump to serialize %cr0 on 386/486

The 386 and 486 needs a jump immediately after setting %cr0 in order
to serialize the pipeline.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---

diff --git a/arch/x86/boot/pmjump.S b/arch/x86/boot/pmjump.S
index 2e559233725a..26baeab3a4d4 100644
--- a/arch/x86/boot/pmjump.S
+++ b/arch/x86/boot/pmjump.S
@@ -31,14 +31,14 @@ protected_mode_jump:
 	xorl	%ebx, %ebx		# Flag to indicate this is a boot
 	movl	%edx, %esi		# Pointer to boot_params table
 	movl	%eax, 2f		# Patch ljmpl instruction
-	jmp	1f			# Short jump to flush instruction q.
 
-1:
 	movw	$__BOOT_DS, %cx
 
 	movl	%cr0, %edx
 	orb	$1, %dl			# Protected mode (PE) bit
 	movl	%edx, %cr0
+	jmp	1f			# Short jump to serialize on 386/486
+1:
 
 	movw	%cx, %ds
 	movw	%cx, %es