From 1ecf91769597650193456f989768e546512c7245 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Tue, 18 Apr 1995 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1995-04-18

---
 pc/mem.h | 3 ++-
 pc/mmu.c | 6 ++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/pc/mem.h b/pc/mem.h
index 202b27a2692bfd8cc0eaa431fa40ae1c18ce7703..d4f16a31089dda898f7d9604e41174548d3b5923 100644
--- a/pc/mem.h
+++ b/pc/mem.h
@@ -109,7 +109,8 @@
  *  physical MMU
  */
 #define	PTEVALID	(1<<0)
-#define	PTEUNCACHED	(1<<4)	
+#define	PTEWT		(1<<3)
+#define	PTEUNCACHED	(1<<4)
 #define PTEWRITE	(1<<1)
 #define	PTERONLY	(0<<1)
 #define	PTEKERNEL	(0<<2)
diff --git a/pc/mmu.c b/pc/mmu.c
index 49f2bcd6752df84fb0c59e5fa72a24e1a29448d0..b0de9f50be8b27340b721845b8c67727431a037d 100644
--- a/pc/mmu.c
+++ b/pc/mmu.c
@@ -168,6 +168,12 @@ mmuinit(void)
 	kpt = xspanalloc(nbytes, BY2PG, 0);
 	for(i = 0; i < npage; i++)
 		kpt[i] = (0+i*BY2PG) | PTEVALID | PTEKERNEL | PTEWRITE;
+	for(i = 0xa0000/BY2PG; i < 0xC0000/BY2PG; i++)
+		kpt[i] = (0+i*BY2PG) | PTEVALID | PTEKERNEL | PTEWRITE | PTEWT;
+	for(i = 0xC0000/BY2PG; i < MB/BY2PG; i++)
+		kpt[i] = (0+i*BY2PG) | PTEVALID | PTEKERNEL | PTEWRITE | PTEUNCACHED;
+	for(i = conf.topofmem/BY2PG; i < 128*MB/BY2PG; i++)
+		kpt[i] = (0+i*BY2PG) | PTEVALID | PTEKERNEL | PTEWRITE | PTEUNCACHED;
 	x = TOPOFF(KZERO);
 	y = ((ulong)kpt)&~KZERO;
 	for(i = 0; i < nkpt; i++)