diff --git a/cbtable.c b/cbtable.c
index 2611a62..c12354c 100644
--- a/cbtable.c
+++ b/cbtable.c
@@ -6,6 +6,7 @@
  * (Written by Eric Biederman <ebiederman@lnxi.com> for Linux Networx)
  * Copyright (C) 2006-2009 coresystems GmbH
  * (Written by Stefan Reinauer <stepan@coresystems.de> for coresystems GmbH)
+ * Copyright (C) 2010 Carl-Daniel Hailfinger
  *
  * 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
@@ -207,11 +208,15 @@
 #else
 	start = 0x0;
 #endif
-	table_area = physmap("low megabyte", start, BYTES_TO_MAP);
+	table_area = physmap_try_ro("low megabyte", start, BYTES_TO_MAP - start);
+	if (!table_area) {
+		msg_perr("Failed getting access to coreboot low tables.\n");
+		return -1;
+	}
 
 	lb_table = find_lb_table(table_area, 0x00000, 0x1000);
 	if (!lb_table)
-		lb_table = find_lb_table(table_area, 0xf0000, BYTES_TO_MAP);
+		lb_table = find_lb_table(table_area, 0xf0000 - start, BYTES_TO_MAP - start);
 	if (lb_table) {
 		struct lb_forward *forward = (struct lb_forward *)
 			(((char *)lb_table) + lb_table->header_bytes);
@@ -219,7 +224,12 @@
 			start = forward->forward;
 			start &= ~(getpagesize() - 1);
 			physunmap(table_area, BYTES_TO_MAP);
-			table_area = physmap("high tables", start, BYTES_TO_MAP);
+			table_area = physmap_try_ro("high tables", start, BYTES_TO_MAP);
+			if (!table_area) {
+				msg_perr("Failed getting access to coreboot "
+					 "high tables.\n");
+				return -1;
+			}
 			lb_table = find_lb_table(table_area, 0x00000, 0x1000);
 		}
 	}
diff --git a/flash.h b/flash.h
index 3d31d44..d8f02bb 100644
--- a/flash.h
+++ b/flash.h
@@ -343,6 +343,7 @@
 
 /* physmap.c */
 void *physmap(const char *descr, unsigned long phys_addr, size_t len);
+void *physmap_try_ro(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);
diff --git a/physmap.c b/physmap.c
index 3a003fe..fba7a53 100644
--- a/physmap.c
+++ b/physmap.c
@@ -3,6 +3,7 @@
  *
  * Copyright (C) 2009 Peter Stuge <peter@stuge.se>
  * Copyright (C) 2009 coresystems GmbH
+ * Copyright (C) 2010 Carl-Daniel Hailfinger
  *
  * 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
@@ -36,6 +37,10 @@
 	return map_physical(phys_addr, len);
 }
 
+/* The OS X driver does not differentiate between mapping types. */
+#define sys_physmap_rw_uncached	sys_physmap
+#define sys_physmap_ro_cached	sys_physmap
+
 void physunmap(void *virt_addr, size_t len)
 {
 	unmap_physical(virt_addr, len);
@@ -51,8 +56,10 @@
 #endif
 
 static int fd_mem = -1;
+static int fd_mem_cached = -1;
 
-void *sys_physmap(unsigned long phys_addr, size_t len)
+/* For MMIO access. Must be uncached, doesn't make sense to restrict to ro. */
+void *sys_physmap_rw_uncached(unsigned long phys_addr, size_t len)
 {
 	void *virt_addr;
 
@@ -69,6 +76,26 @@
 	return MAP_FAILED == virt_addr ? NULL : virt_addr;
 }
 
+/* For reading DMI/coreboot/whatever tables. We should never write, and we
+ * do not care about caching.
+ */
+void *sys_physmap_ro_cached(unsigned long phys_addr, size_t len)
+{
+	void *virt_addr;
+
+	if (-1 == fd_mem_cached) {
+		/* Open the memory device CACHED. */
+		if (-1 == (fd_mem_cached = open(MEM_DEV, O_RDWR))) {
+			perror("Critical error: open(" MEM_DEV ")");
+			exit(2);
+		}
+	}
+
+	virt_addr = mmap(0, len, PROT_READ, MAP_SHARED,
+			 fd_mem_cached, (off_t)phys_addr);
+	return MAP_FAILED == virt_addr ? NULL : virt_addr;
+}
+
 void physunmap(void *virt_addr, size_t len)
 {
 	if (len == 0) {
@@ -80,7 +107,12 @@
 }
 #endif
 
-void *physmap(const char *descr, unsigned long phys_addr, size_t len)
+#define PHYSMAP_NOFAIL	0
+#define PHYSMAP_MAYFAIL	1
+#define PHYSMAP_RW	0
+#define PHYSMAP_RO	1
+
+void *physmap_common(const char *descr, unsigned long phys_addr, size_t len, int mayfail, int readonly)
 {
 	void *virt_addr;
 
@@ -100,7 +132,11 @@
 			descr, (unsigned long)len, phys_addr);
 	}
 
-	virt_addr = sys_physmap(phys_addr, len);
+	if (readonly) {
+		virt_addr = sys_physmap_ro_cached(phys_addr, len);
+	} else {
+		virt_addr = sys_physmap_rw_uncached(phys_addr, len);
+	}
 
 	if (NULL == virt_addr) {
 		if (NULL == descr)
@@ -114,12 +150,23 @@
 			fprintf(stderr, "You can override CONFIG_X86_PAT at boot with the nopat kernel parameter but\n");
 			fprintf(stderr, "disabling the other option unfortunately requires a kernel recompile. Sorry!\n");
 		}
-		exit(3);
+		if (!mayfail)
+			exit(3);
 	}
 
 	return virt_addr;
 }
 
+void *physmap(const char *descr, unsigned long phys_addr, size_t len)
+{
+	return physmap_common(descr, phys_addr, len, PHYSMAP_NOFAIL, PHYSMAP_RW);
+}
+
+void *physmap_try_ro(const char *descr, unsigned long phys_addr, size_t len)
+{
+	return physmap_common(descr, phys_addr, len, PHYSMAP_MAYFAIL, PHYSMAP_RO);
+}
+
 #ifdef __linux__
 /*
  * Reading and writing to MSRs, however requires instructions rdmsr/wrmsr,