From 6a587f5aa32b9eee91ccb191ddbbdde55a120f0e Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 23 May 2001 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2001-05-23

---
 pc/memory.c | 8 ++++++++
 pc/screen.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/pc/memory.c b/pc/memory.c
index 4f88147dec107a2a7d129e47e75ec88717762a8f..e48539460bdb09121eaa7994018724ce1c0b7ea7 100644
--- a/pc/memory.c
+++ b/pc/memory.c
@@ -225,6 +225,14 @@ umbscan(void)
 	 */
 	p = KADDR(0xC0000);
 	while(p < (uchar*)KADDR(0xE0000)){
+		if (p[0] == 0x55 && p[1] == 0xAA) {
+			/* Skip p[2] chunks of 512 bytes.  Test for 0x55 AA before
+			     poking obtrusively, or else the Thinkpad X20 dies when
+			     setting up the cardbus (PB) */
+			p += p[2] * 512;
+			continue;
+		}
+
 		p[0] = 0xCC;
 		p[2*KB-1] = 0xCC;
 		if(p[0] != 0xCC || p[2*KB-1] != 0xCC){
diff --git a/pc/screen.h b/pc/screen.h
index cf6f71ced3478c8eaf6f69048e89cbd4a002b2cf..52f2942c4a27f2e42f5b19c89754ee0f893298d0 100644
--- a/pc/screen.h
+++ b/pc/screen.h
@@ -140,6 +140,7 @@ extern void	blankscreen(int);
 extern void	deletescreenimage(void);
 extern int		drawhasclients(void);
 extern ulong	blanktime;
+extern uchar*	attachscreen(Rectangle*, ulong*, int*, int*, int*);
 
 /* vga.c */
 extern void	vgascreenwin(VGAscr*);