diff --git a/[refs] b/[refs]
index 9156105c45bf..760154e180a8 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 6ecbf01c7ce4c0f4c3bdfa0e64ac6258328fda6c
+refs/heads/master: 5595b528b49a702c0428c0762bab60999648254c
diff --git a/trunk/drivers/pci/intel-iommu.c b/trunk/drivers/pci/intel-iommu.c
index cb5cae3e0205..83cabdc118db 100644
--- a/trunk/drivers/pci/intel-iommu.c
+++ b/trunk/drivers/pci/intel-iommu.c
@@ -2000,6 +2000,16 @@ static int iommu_prepare_identity_map(struct pci_dev *pdev,
 	       "IOMMU: Setting identity map for device %s [0x%Lx - 0x%Lx]\n",
 	       pci_name(pdev), start, end);
 	
+	if (end < start) {
+		WARN(1, "Your BIOS is broken; RMRR ends before it starts!\n"
+			"BIOS vendor: %s; Ver: %s; Product Version: %s\n",
+			dmi_get_system_info(DMI_BIOS_VENDOR),
+			dmi_get_system_info(DMI_BIOS_VERSION),
+		     dmi_get_system_info(DMI_PRODUCT_VERSION));
+		ret = -EIO;
+		goto error;
+	}
+
 	if (end >> agaw_to_width(domain->agaw)) {
 		WARN(1, "Your BIOS is broken; RMRR exceeds permitted address width (%d bits)\n"
 		     "BIOS vendor: %s; Ver: %s; Product Version: %s\n",