From: H. Peter Anvin <hpa@zytor.com>
Date: Mon, 5 Nov 2007 00:34:38 +0000 (-0800)
Subject: Setting cr0 requires a jmp to synchronize on 386/486
X-Git-Tag: syslinux-3.53-pre3~3
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=28b46657095873e98434959075b7717ec22117c1;p=profile%2Fivi%2Fsyslinux.git

Setting cr0 requires a jmp to synchronize on 386/486

The 386 and 486 requires a jmp after any setting of cr0.  It can be a
near jmp, but those processors do not correctly synchronize without
it.

We have jmps after setting cr0 in all spots except one, so make that
happen correctly.
---

diff --git a/bcopy32.inc b/bcopy32.inc
index 87190d8..4df5e43 100644
--- a/bcopy32.inc
+++ b/bcopy32.inc
@@ -532,7 +532,8 @@ trampoline_to_pm:
 		mov eax,cr0
 		or al,1
 		mov cr0,eax		; Enter protected mode
-		mov ax,PM_DS32		; 32-bit data segment selector
+		jmp .next		; Near jump to synchronize on 386/486
+.next:		mov ax,PM_DS32		; 32-bit data segment selector
 		mov es,ax
 		mov ds,ax
 		mov ss,ax