From f5e591f9bd5876c524ea2c2f415d8516258011cf Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 19 Oct 1994 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1994-10-19

---
 carrera/io.h   |  1 +
 carrera/main.c | 18 +++++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/carrera/io.h b/carrera/io.h
index a7eb9e140adc98923e9353a00e0161d0fe299140..8aac77e4a16316cd4598d19329457fc9f90e9b0c 100644
--- a/carrera/io.h
+++ b/carrera/io.h
@@ -9,6 +9,7 @@ enum
 	Devicephys	= 0x80000000,
 	Eisaphys	= 0x90000000,	/* IO port physical */
 	Devicevirt	= 0xE0000000,
+	  MCTgcr	= 0xE0000004,
 	Dmabase		= 0xE0000100,	
 	  R4030ier	= 0xE00000EC,	/* Interrupt enable register */
 	  R4030ipr	= 0xE00000EC,	/* Interrupt pending register */
diff --git a/carrera/main.c b/carrera/main.c
index 1cc7996f44c8aef2d0ce231b3bde0bd3008d5e97..e76e235b9fe539e8d643d089ca0c284135bb73a6 100644
--- a/carrera/main.c
+++ b/carrera/main.c
@@ -424,6 +424,22 @@ exit(long type)
 	firmware(type);
 }
 
+ulong
+memsize(void)
+{
+	ulong gcr;
+
+	gcr = IO(ulong, MCTgcr);
+	/* Check for bank one enable -
+	 * assumes both have 4Meg SIMMS
+	 */
+	if(gcr & 0x20){
+		memset(UNCACHED(void, 16*MB), 0, 16*MB);
+		return 32*MB;
+	}
+	return 16*MB;
+}
+
 void
 confinit(void)
 {
@@ -431,7 +447,7 @@ confinit(void)
 
 	ktop = PGROUND((ulong)end);
 	ktop = PADDR(ktop);
-	top = (16*1024*1024)/BY2PG;
+	top = memsize()/BY2PG;
 
 	conf.base0 = 0;
 	conf.npage0 = top;