From 0264d03fc1ac26b65ee4c28b136d88794cb88214 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@zytor.com>
Date: Thu, 8 Feb 2007 09:58:09 -0800
Subject: [PATCH] PXELINUX: ES:BX -> PXENV+, so we can't have ES:DI -> $PnP.

This broke chainbooting FreeBSD at least.
---
 NEWS         | 1 +
 bootsect.inc | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/NEWS b/NEWS
index 43912b7..c8e472f 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,7 @@ Changes in 3.36:
 	* New MBR which can boot from logical partitions.
 	* SYSLINUX: Fix bug in detecting special extensions which was
 	  introduced in 3.35 :(
+	* PXELINUX: Unbreak chainbooting FreeBSD (and possibly others.)
 
 Changes in 3.35:
 	* MEMDISK: New "safeint" mode.
diff --git a/bootsect.inc b/bootsect.inc
index d52aefb..66e1886 100644
--- a/bootsect.inc
+++ b/bootsect.inc
@@ -136,6 +136,11 @@ replace_bootstrap:
 		mov [es:di+12],esi	; New ESI
 		mov [es:di+6],bx	; New DS
 
+%ifndef IS_PXELINUX
+		; DON'T DO THIS FOR PXELINUX...
+		; For PXE, ES:BX -> PXENV+, and this would corrupt
+		; that use.
+
 		; Hunt for $PnP header if one exists
 		mov ax,0F000h
 		mov fs,ax
@@ -163,6 +168,7 @@ replace_bootstrap:
 		; Found a valid $PnP header, point ES:DI to it
 		mov [es:di+8], bx	; New DI
 		mov [es:di+4], fs	; New ES
+%endif
 
 .donepnp:
 		pop ax			; Copy list count
-- 
2.7.4