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>

1 files changed, 2 insertions, 2 deletions

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