diff --git a/chipset_enable.c b/chipset_enable.c
index a375cd7..6ac829b 100644
--- a/chipset_enable.c
+++ b/chipset_enable.c
@@ -2,7 +2,7 @@
  * This file is part of the flashrom project.
  *
  * Copyright (C) 2000 Silicon Integrated System Corporation
- * Copyright (C) 2005-2009 coresystems GmbH <stepan@coresystems.de>
+ * Copyright (C) 2005-2009 coresystems GmbH
  * Copyright (C) 2006 Uwe Hermann <uwe@hermann-uwe.de>
  *
  * This program is free software; you can redistribute it and/or modify
@@ -527,91 +527,35 @@
 
 /**
  * Geode systems write protect the BIOS via RCONFs (cache settings similar
- * to MTRRs). To unlock, change MSR 0x1808 top byte to 0x22. Reading and
- * writing to MSRs, however requires instructions rdmsr/wrmsr, which are
- * ring0 privileged instructions so only the kernel can do the read/write.
- * This function, therefore, requires that the msr kernel module be loaded
- * to access these instructions from user space using device /dev/cpu/0/msr.
- *
- * This hard-coded location could have potential problems on SMP machines
- * since it assumes cpu0, but it is safe on the Geode which is not SMP.
+ * to MTRRs). To unlock, change MSR 0x1808 top byte to 0x22. 
  *
  * Geode systems also write protect the NOR flash chip itself via MSR_NORF_CTL.
  * To enable write to NOR Boot flash for the benefit of systems that have such
  * a setup, raise MSR 0x51400018 WE_CS3 (write enable Boot Flash Chip Select).
- *
- * This is probably not portable beyond Linux.
  */
 static int enable_flash_cs5536(struct pci_dev *dev, const char *name)
 {
 #define MSR_RCONF_DEFAULT	0x1808
 #define MSR_NORF_CTL		0x51400018
 
-	int fd_msr;
-	unsigned char buf[8];
+	msr_t msr;
 
-	fd_msr = open("/dev/cpu/0/msr", O_RDWR);
-	if (fd_msr == -1) {
-		perror("open(/dev/cpu/0/msr)");
-		printf("Cannot operate on MSR. Did you run 'modprobe msr'?\n");
+	/* Geode only has a single core */
+	if (setup_cpu_msr(0))
 		return -1;
+
+	msr = rdmsr(MSR_RCONF_DEFAULT);
+	if ((msr.hi >> 24) != 0x22) {
+		msr.hi &= 0xfbffffff;
+		wrmsr(MSR_RCONF_DEFAULT, msr);
 	}
 
-	if (lseek64(fd_msr, (off64_t) MSR_RCONF_DEFAULT, SEEK_SET) == -1) {
-		perror("lseek64");
-		close(fd_msr);
-		return -1;
-	}
-
-	if (read(fd_msr, buf, 8) != 8) {
-		perror("read msr");
-		close(fd_msr);
-		return -1;
-	}
-
-	if (buf[7] != 0x22) {
-		buf[7] &= 0xfb;
-		if (lseek64(fd_msr, (off64_t) MSR_RCONF_DEFAULT,
-			    SEEK_SET) == -1) {
-			perror("lseek64");
-			close(fd_msr);
-			return -1;
-		}
-
-		if (write(fd_msr, buf, 8) < 0) {
-			perror("msr write");
-			close(fd_msr);
-			return -1;
-		}
-	}
-
-	if (lseek64(fd_msr, (off64_t) MSR_NORF_CTL, SEEK_SET) == -1) {
-		perror("lseek64");
-		close(fd_msr);
-		return -1;
-	}
-
-	if (read(fd_msr, buf, 8) != 8) {
-		perror("read msr");
-		close(fd_msr);
-		return -1;
-	}
-
+	msr = rdmsr(MSR_NORF_CTL);
 	/* Raise WE_CS3 bit. */
-	buf[0] |= 0x08;
+	msr.lo |= 0x08;
+	wrmsr(MSR_NORF_CTL, msr);
 
-	if (lseek64(fd_msr, (off64_t) MSR_NORF_CTL, SEEK_SET) == -1) {
-		perror("lseek64");
-		close(fd_msr);
-		return -1;
-	}
-	if (write(fd_msr, buf, 8) < 0) {
-		perror("msr write");
-		close(fd_msr);
-		return -1;
-	}
-
-	close(fd_msr);
+	cleanup_cpu_msr();
 
 #undef MSR_RCONF_DEFAULT
 #undef MSR_NORF_CTL
diff --git a/flash.h b/flash.h
index 7383b5d..b421cf9 100644
--- a/flash.h
+++ b/flash.h
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2000 Silicon Integrated System Corporation
  * Copyright (C) 2000 Ronald G. Minnich <rminnich@gmail.com>
- * Copyright (C) 2005-2007 coresystems GmbH <stepan@coresystems.de>
+ * Copyright (C) 2005-2009 coresystems GmbH
  * Copyright (C) 2006-2009 Carl-Daniel Hailfinger
  *
  * This program is free software; you can redistribute it and/or modify
@@ -301,6 +301,13 @@
 /* physmap.c */
 void *physmap(const char *descr, unsigned long phys_addr, size_t len);
 void physunmap(void *virt_addr, size_t len);
+int setup_cpu_msr(int cpu);
+void cleanup_cpu_msr(void);
+#ifndef __DARWIN__
+typedef struct { uint32_t hi, lo; } msr_t;
+msr_t rdmsr(int addr);
+int wrmsr(int addr, msr_t msr);
+#endif
 
 /* internal.c */
 struct pci_dev *pci_dev_find_filter(struct pci_filter filter);
diff --git a/physmap.c b/physmap.c
index 2246dfa..e03a23d 100644
--- a/physmap.c
+++ b/physmap.c
@@ -2,6 +2,7 @@
  * This file is part of the flashrom project.
  *
  * Copyright (C) 2009 Peter Stuge <peter@stuge.se>
+ * Copyright (C) 2009 coresystems GmbH
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -21,6 +22,7 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <stdlib.h>
+#include <string.h>
 #include <errno.h>
 #include "flash.h"
 
@@ -117,3 +119,136 @@
 
 	return virt_addr;
 }
+
+#ifdef __linux__
+/*
+ * Reading and writing to MSRs, however requires instructions rdmsr/wrmsr,
+ * which are ring0 privileged instructions so only the kernel can do the
+ * read/write.  This function, therefore, requires that the msr kernel module
+ * be loaded to access these instructions from user space using device
+ * /dev/cpu/0/msr.
+ */
+
+static int fd_msr = -1;
+
+msr_t rdmsr(int addr)
+{
+	uint8_t buf[8];
+	msr_t msr = { 0xffffffff, 0xffffffff };
+
+	if (lseek(fd_msr, (off_t) addr, SEEK_SET) == -1) {
+		perror("Could not lseek() to MSR");
+		close(fd_msr);
+		exit(1);
+	}
+
+	if (read(fd_msr, buf, 8) == 8) {
+		msr.lo = *(uint32_t *)buf;
+		msr.hi = *(uint32_t *)(buf + 4);
+
+		return msr;
+	}
+
+	if (errno != EIO) {
+		// A severe error.
+		perror("Could not read() MSR");
+		close(fd_msr);
+		exit(1);
+	}
+
+	return msr;
+}
+
+int wrmsr(int addr, msr_t msr)
+{
+	if (lseek(fd_msr, (off_t) addr, SEEK_SET) == -1) {
+		perror("Could not lseek() to MSR");
+		close(fd_msr);
+		exit(1);
+	}
+
+	if (write(fd_msr, &msr, 8) != 8 && errno != EIO) {
+		perror("Could not write() MSR");
+		close(fd_msr);
+		exit(1);
+	}
+
+	/* some MSRs must not be written */
+	if (errno == EIO)
+		return -1;
+
+	return 0;
+}
+
+int setup_cpu_msr(int cpu)
+{
+	char msrfilename[64];
+	memset(msrfilename, 0, 64);
+	sprintf(msrfilename, "/dev/cpu/%d/msr", cpu);
+
+	if (fd_msr != -1) {
+		printf("MSR was already initialized\n");
+		return -1;
+	}
+
+	fd_msr = open(msrfilename, O_RDWR);
+
+	if (fd_msr < 0) {
+		perror("Error while opening /dev/cpu/0/msr");
+		printf("Did you run 'modprobe msr'?\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+void cleanup_cpu_msr(void)
+{
+	if (fd_msr == -1) {
+		printf("No MSR initialized.\n");
+		return;
+	}
+
+	close(fd_msr);
+
+	/* Clear MSR file descriptor */
+	fd_msr = -1;
+}
+#else
+#ifdef __DARWIN__
+int setup_cpu_msr(int cpu)
+{
+	// Always succeed for now
+	return 0;
+}
+
+void cleanup_cpu_msr(void)
+{
+	// Nothing, yet.
+}
+#else
+msr_t rdmsr(int addr)
+{
+	msr_t ret = { 0xffffffff, 0xffffffff };
+
+	return ret;
+}
+
+int wrmsr(int addr, msr_t msr)
+{
+	return -1;
+}
+
+int setup_cpu_msr(int cpu)
+{
+	printf("No MSR support for your OS yet.\n");
+	return -1;
+}
+
+void cleanup_cpu_msr(void)
+{
+	// Nothing, yet.
+}
+#endif
+#endif
+