From 7ed192906a2144ebc8ca2925a85d27b9c5355668 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Sun, 4 Nov 2007 17:50:12 -0800 Subject: [PATCH] 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 --- arch/x86/boot/pmjump.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/pmjump.S b/arch/x86/boot/pmjump.S index 2e559233725..26baeab3a4d 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 -- 2.41.1