diff --git a/src/device/device_util.c b/src/device/device_util.c
index 56afefdc87..157f7b7443 100644
--- a/src/device/device_util.c
+++ b/src/device/device_util.c
@@ -888,6 +888,26 @@ void fixed_mem_resource(device_t dev, unsigned long index,
 	resource->flags |= type;
 }
 
+void mmconf_resource_init(struct resource *resource, resource_t base,
+	int buses)
+{
+	resource->base = base;
+	resource->size = buses * MiB;
+	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
+		IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
+
+	printk(BIOS_DEBUG, "Adding PCIe enhanced config space BAR "
+			"0x%08lx-0x%08lx.\n", (unsigned long)(resource->base),
+			(unsigned long)(resource->base + resource->size));
+}
+
+void mmconf_resource(struct device *dev, unsigned long index)
+{
+	struct resource *resource = new_resource(dev, index);
+	mmconf_resource_init(resource, CONFIG_MMCONF_BASE_ADDRESS,
+		CONFIG_MMCONF_BUS_NUMBER);
+}
+
 void tolm_test(void *gp, struct device *dev, struct resource *new)
 {
 	struct resource **best_p = gp;
diff --git a/src/include/device/device.h b/src/include/device/device.h
index 95fabf42c8..d81399d6ef 100644
--- a/src/include/device/device.h
+++ b/src/include/device/device.h
@@ -234,6 +234,9 @@ void pci_domain_scan_bus(struct device *dev);
 void fixed_mem_resource(device_t dev, unsigned long index,
 		  unsigned long basek, unsigned long sizek, unsigned long type);
 
+void mmconf_resource_init(struct resource *res, resource_t base, int buses);
+void mmconf_resource(struct device *dev, unsigned long index);
+
 void scan_smbus(device_t bus);
 void scan_static_bus(device_t bus);
 void scan_lpc_bus(device_t bus);
diff --git a/src/northbridge/amd/agesa/family10/northbridge.c b/src/northbridge/amd/agesa/family10/northbridge.c
index 2a54892575..00799a55d8 100644
--- a/src/northbridge/amd/agesa/family10/northbridge.c
+++ b/src/northbridge/amd/agesa/family10/northbridge.c
@@ -424,6 +424,13 @@ static void amdfam10_read_resources(device_t dev)
 			amdfam10_link_read_bases(dev, nodeid, link->link_num);
 		}
 	}
+
+	/*
+	 * This MMCONF resource must be reserved in the PCI domain.
+	 * It is not honored by the coreboot resource allocator if it is in
+	 * the CPU_CLUSTER.
+	 */
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void amdfam10_set_resource(device_t dev, struct resource *resource,
@@ -530,6 +537,11 @@ static void amdfam10_set_resources(device_t dev)
 			assign_resources(bus);
 		}
 	}
+
+	res = find_resource(dev, 0xc0010058);
+	if (res) {
+		report_resource_stored(dev, res, " <mmconfig>");
+	}
 }
 
 static void mcf0_control_init(struct device *dev)
@@ -1096,19 +1108,10 @@ static void cpu_bus_init(device_t dev)
 
 static void cpu_bus_read_resources(device_t dev)
 {
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096*256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		IORESOURCE_FIXED | IORESOURCE_STORED |  IORESOURCE_ASSIGNED;
 }
 
 static void cpu_bus_set_resources(device_t dev)
 {
-	struct resource *resource = find_resource(dev, 0xc0010058);
-	if (resource) {
-		report_resource_stored(dev, resource, " <mmconfig>");
-	}
 	pci_dev_set_resources(dev);
 }
 
diff --git a/src/northbridge/amd/agesa/family12/northbridge.c b/src/northbridge/amd/agesa/family12/northbridge.c
index 6f2896aa5a..e7363f6669 100644
--- a/src/northbridge/amd/agesa/family12/northbridge.c
+++ b/src/northbridge/amd/agesa/family12/northbridge.c
@@ -300,6 +300,14 @@ static void read_resources(device_t dev)
 			amdfam12_link_read_bases(dev, nodeid, link->link_num);
 		}
 	}
+
+	/*
+	 * This MMCONF resource must be reserved in the PCI domain.
+	 * It is not honored by the coreboot resource allocator if it is in
+	 * the CPU_CLUSTER.
+	 */
+	mmconf_resource(dev, 0xc0010058);
+
 	printk(BIOS_DEBUG, "Fam12h - northbridge.c - %s - End.\n",__func__);
 }
 
@@ -649,11 +657,6 @@ static void cpu_bus_read_resources(device_t dev)
 {
 	printk(BIOS_DEBUG, "\nFam12h - northbridge.c - %s - Start.\n",__func__);
 
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096*256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		IORESOURCE_FIXED | IORESOURCE_STORED |  IORESOURCE_ASSIGNED;
 	printk(BIOS_DEBUG, "Fam12h - northbridge.c - %s - End.\n",__func__);
 }
 
diff --git a/src/northbridge/amd/agesa/family14/northbridge.c b/src/northbridge/amd/agesa/family14/northbridge.c
index f92183e8d5..d66e83a0b5 100644
--- a/src/northbridge/amd/agesa/family14/northbridge.c
+++ b/src/northbridge/amd/agesa/family14/northbridge.c
@@ -302,11 +302,7 @@ static void nb_read_resources(device_t dev)
 	 * It is not honored by the coreboot resource allocator if it is in
 	 * the CPU_CLUSTER.
 	 */
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096 * 256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-	    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void set_resource(device_t dev, struct resource *resource, u32 nodeid)
diff --git a/src/northbridge/amd/agesa/family15/northbridge.c b/src/northbridge/amd/agesa/family15/northbridge.c
index 5fc9833445..77ac720bb1 100644
--- a/src/northbridge/amd/agesa/family15/northbridge.c
+++ b/src/northbridge/amd/agesa/family15/northbridge.c
@@ -326,11 +326,7 @@ static void nb_read_resources(device_t dev)
 	 * It is not honored by the coreboot resource allocator if it is in
 	 * the CPU_CLUSTER.
 	 */
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096 * 256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-	    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void set_resource(device_t dev, struct resource *resource, u32 nodeid)
diff --git a/src/northbridge/amd/agesa/family15rl/northbridge.c b/src/northbridge/amd/agesa/family15rl/northbridge.c
index b5f76909ca..d4970ef9e7 100644
--- a/src/northbridge/amd/agesa/family15rl/northbridge.c
+++ b/src/northbridge/amd/agesa/family15rl/northbridge.c
@@ -326,11 +326,7 @@ static void read_resources(struct device *dev)
 	 * It is not honored by the coreboot resource allocator if it is in
 	 * the CPU_CLUSTER.
 	 */
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096 * 256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-	    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void set_resource(struct device *dev, struct resource *resource, u32 nodeid)
diff --git a/src/northbridge/amd/agesa/family15tn/northbridge.c b/src/northbridge/amd/agesa/family15tn/northbridge.c
index 2353126049..7d36b13d29 100644
--- a/src/northbridge/amd/agesa/family15tn/northbridge.c
+++ b/src/northbridge/amd/agesa/family15tn/northbridge.c
@@ -325,11 +325,7 @@ static void nb_read_resources(device_t dev)
 	 * It is not honored by the coreboot resource allocator if it is in
 	 * the CPU_CLUSTER.
 	 */
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096 * 256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-	    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void set_resource(device_t dev, struct resource *resource, u32 nodeid)
diff --git a/src/northbridge/amd/agesa/family16kb/northbridge.c b/src/northbridge/amd/agesa/family16kb/northbridge.c
index 63e1c2e556..641487f1c7 100644
--- a/src/northbridge/amd/agesa/family16kb/northbridge.c
+++ b/src/northbridge/amd/agesa/family16kb/northbridge.c
@@ -325,11 +325,7 @@ static void read_resources(device_t dev)
 	 * It is not honored by the coreboot resource allocator if it is in
 	 * the APIC_CLUSTER.
 	 */
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096 * 256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		IORESOURCE_FIXED | IORESOURCE_STORED |  IORESOURCE_ASSIGNED;
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void set_resource(device_t dev, struct resource *resource, u32 nodeid)
diff --git a/src/northbridge/amd/amdfam10/northbridge.c b/src/northbridge/amd/amdfam10/northbridge.c
index cc2e6f923b..43480d2db1 100644
--- a/src/northbridge/amd/amdfam10/northbridge.c
+++ b/src/northbridge/amd/amdfam10/northbridge.c
@@ -741,14 +741,7 @@ static void amdfam10_domain_read_resources(device_t dev)
 	pci_domain_read_resources(dev);
 
 	/* We have MMCONF_SUPPORT, create the resource window. */
-	struct resource *res = new_resource(dev, 0xc0010058);
-	res->base = CONFIG_MMCONF_BASE_ADDRESS;
-	res->size = CONFIG_MMCONF_BUS_NUMBER * 1024 * 1024;	/* Each bus needs 1M */
-	res->align = log2(res->size);
-	res->gran = log2(res->size);
-	res->limit = 0xffffffffffffffffULL;			/* 64-bit location allowed */
-	res->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		IORESOURCE_FIXED | IORESOURCE_STORED |  IORESOURCE_ASSIGNED;
+	mmconf_resource(dev, 0xc0010058);
 
 	/* Reserve lower DRAM region to force PCI MMIO region to correct location above 0xefffffff */
 	ram_resource(dev, 7, 0, rdmsr(TOP_MEM).lo >> 10);
diff --git a/src/northbridge/amd/pi/00630F01/northbridge.c b/src/northbridge/amd/pi/00630F01/northbridge.c
index 4872db0f68..f863c73f7c 100644
--- a/src/northbridge/amd/pi/00630F01/northbridge.c
+++ b/src/northbridge/amd/pi/00630F01/northbridge.c
@@ -309,15 +309,6 @@ static void amdfam15_link_read_bases(device_t dev, u32 nodeid, u32 link)
 
 }
 
-static void enable_mmconf_resource(device_t dev)
-{
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096 * 256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-}
-
 static void read_resources(device_t dev)
 {
 	u32 nodeid;
@@ -335,7 +326,7 @@ static void read_resources(device_t dev)
 	 * It is not honored by the coreboot resource allocator if it is in
 	 * the CPU_CLUSTER.
 	 */
-	enable_mmconf_resource(dev);
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void set_resource(device_t dev, struct resource *resource, u32 nodeid)
diff --git a/src/northbridge/amd/pi/00660F01/northbridge.c b/src/northbridge/amd/pi/00660F01/northbridge.c
index 4c1254c0fe..941c39aa31 100644
--- a/src/northbridge/amd/pi/00660F01/northbridge.c
+++ b/src/northbridge/amd/pi/00660F01/northbridge.c
@@ -304,15 +304,6 @@ static void amdfam15_link_read_bases(device_t dev, u32 nodeid, u32 link)
 
 }
 
-static void enable_mmconf_resource(device_t dev)
-{
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096 * 256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-}
-
 static void read_resources(device_t dev)
 {
 	u32 nodeid;
@@ -330,7 +321,7 @@ static void read_resources(device_t dev)
 	 * It is not honored by the coreboot resource allocator if it is in
 	 * the CPU_CLUSTER.
 	 */
-	enable_mmconf_resource(dev);
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void set_resource(device_t dev, struct resource *resource, u32 nodeid)
diff --git a/src/northbridge/amd/pi/00670F00/northbridge.c b/src/northbridge/amd/pi/00670F00/northbridge.c
index 9a39410f49..b258aedaf4 100644
--- a/src/northbridge/amd/pi/00670F00/northbridge.c
+++ b/src/northbridge/amd/pi/00670F00/northbridge.c
@@ -304,15 +304,6 @@ static void amdfam15_link_read_bases(device_t dev, u32 nodeid, u32 link)
 
 }
 
-static void enable_mmconf_resource(device_t dev)
-{
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096 * 256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-}
-
 static void read_resources(device_t dev)
 {
 	u32 nodeid;
@@ -330,7 +321,7 @@ static void read_resources(device_t dev)
 	 * It is not honored by the coreboot resource allocator if it is in
 	 * the CPU_CLUSTER.
 	 */
-	enable_mmconf_resource(dev);
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void set_resource(device_t dev, struct resource *resource, u32 nodeid)
diff --git a/src/northbridge/amd/pi/00730F01/northbridge.c b/src/northbridge/amd/pi/00730F01/northbridge.c
index 44f91e2328..dbb41815c7 100644
--- a/src/northbridge/amd/pi/00730F01/northbridge.c
+++ b/src/northbridge/amd/pi/00730F01/northbridge.c
@@ -312,15 +312,6 @@ static void amdfam16_link_read_bases(device_t dev, u32 nodeid, u32 link)
 
 }
 
-static void enable_mmconf_resource(device_t dev)
-{
-	struct resource *resource = new_resource(dev, 0xc0010058);
-	resource->base = CONFIG_MMCONF_BASE_ADDRESS;
-	resource->size = CONFIG_MMCONF_BUS_NUMBER * 4096 * 256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-}
-
 static void read_resources(device_t dev)
 {
 	u32 nodeid;
@@ -338,7 +329,7 @@ static void read_resources(device_t dev)
 	 * It is not honored by the coreboot resource allocator if it is in
 	 * the CPU_CLUSTER.
 	 */
-	enable_mmconf_resource(dev);
+	mmconf_resource(dev, 0xc0010058);
 }
 
 static void set_resource(device_t dev, struct resource *resource, u32 nodeid)
diff --git a/src/northbridge/intel/fsp_rangeley/northbridge.c b/src/northbridge/intel/fsp_rangeley/northbridge.c
index f01333e4a0..0134eff568 100644
--- a/src/northbridge/intel/fsp_rangeley/northbridge.c
+++ b/src/northbridge/intel/fsp_rangeley/northbridge.c
@@ -57,13 +57,12 @@ int bridge_silicon_revision(void)
 static const int legacy_hole_base_k = 0xa0000 / 1024;
 static const int legacy_hole_size_k = 384;
 
-static int get_pcie_bar(u32 *base, u32 *len)
+static int get_pcie_bar(u32 *base)
 {
 	device_t dev;
 	u32 pciexbar_reg;
 
 	*base = 0;
-	*len = 0;
 
 	dev = dev_find_slot(0, PCI_DEVFN(0, 0));
 	if (!dev)
@@ -76,25 +75,13 @@ static int get_pcie_bar(u32 *base, u32 *len)
 
 	*base = pciexbar_reg & ((1 << 31) | (1 << 30) | (1 << 29) |
 				(1 << 28));
-	*len = 256 * 1024 * 1024; /* 256MB ECAM range */
-	return 1;
+	return 256;
 
 }
 
 static int add_fixed_resources(struct device *dev, int index)
 {
 	struct resource *resource;
-	u32 pcie_config_base, pcie_config_size;
-
-	if (get_pcie_bar(&pcie_config_base, &pcie_config_size)) {
-		printk(BIOS_DEBUG, "Adding PCIe config bar base=0x%08x "
-		       "size=0x%x\n", pcie_config_base, pcie_config_size);
-		resource = new_resource(dev, index++);
-		resource->base = (resource_t) pcie_config_base;
-		resource->size = (resource_t) pcie_config_size;
-		resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-	}
 
 	resource = new_resource(dev, index++); /* Local APIC */
 	resource->base = LAPIC_DEFAULT_BASE;
@@ -154,9 +141,19 @@ static void mc_add_dram_resources(device_t dev)
 
 static void mc_read_resources(device_t dev)
 {
+	u32 pcie_config_base;
+	int buses;
+
 	/* Call the normal read_resources */
 	pci_dev_read_resources(dev);
 
+	/* We use 0xcf as an unused index for our PCIe bar so that we find it again */
+	buses = get_pcie_bar(&pcie_config_base);
+	if (buses) {
+		struct resource *resource = new_resource(dev, 0xcf);
+		mmconf_resource_init(resource, pcie_config_base, buses);
+	}
+
 	/* Calculate and add DRAM resources. */
 	mc_add_dram_resources(dev);
 }
diff --git a/src/northbridge/intel/fsp_sandybridge/northbridge.c b/src/northbridge/intel/fsp_sandybridge/northbridge.c
index 50615b5f2d..c9f6e1c061 100644
--- a/src/northbridge/intel/fsp_sandybridge/northbridge.c
+++ b/src/northbridge/intel/fsp_sandybridge/northbridge.c
@@ -62,13 +62,12 @@ int bridge_silicon_revision(void)
 static const int legacy_hole_base_k = 0xa0000 / 1024;
 static const int legacy_hole_size_k = 384;
 
-static int get_pcie_bar(u32 *base, u32 *len)
+static int get_pcie_bar(u32 *base)
 {
 	device_t dev;
 	u32 pciexbar_reg;
 
 	*base = 0;
-	*len = 0;
 
 	dev = dev_find_slot(0, PCI_DEVFN(0, 0));
 	if (!dev)
@@ -82,16 +81,13 @@ static int get_pcie_bar(u32 *base, u32 *len)
 	switch ((pciexbar_reg >> 1) & 3) {
 	case 0: // 256MB
 		*base = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28));
-		*len = 256 * 1024 * 1024;
-		return 1;
+		return 256;
 	case 1: // 128M
 		*base = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28)|(1 << 27));
-		*len = 128 * 1024 * 1024;
-		return 1;
+		return 128;
 	case 2: // 64M
 		*base = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28)|(1 << 27)|(1 << 26));
-		*len = 64 * 1024 * 1024;
-		return 1;
+		return 64;
 	}
 
 	return 0;
@@ -99,21 +95,8 @@ static int get_pcie_bar(u32 *base, u32 *len)
 
 static void add_fixed_resources(struct device *dev, int index)
 {
-	struct resource *resource;
-	u32 pcie_config_base, pcie_config_size;
-
 	mmio_resource(dev, index++, uma_memory_base >> 10, uma_memory_size >> 10);
 
-	if (get_pcie_bar(&pcie_config_base, &pcie_config_size)) {
-		printk(BIOS_DEBUG, "Adding PCIe config bar base=0x%08x "
-		       "size=0x%x\n", pcie_config_base, pcie_config_size);
-		resource = new_resource(dev, index++);
-		resource->base = (resource_t) pcie_config_base;
-		resource->size = (resource_t) pcie_config_size;
-		resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-	}
-
 	mmio_resource(dev, index++, legacy_hole_base_k, legacy_hole_size_k);
 }
 
@@ -256,24 +239,17 @@ static struct device_operations pci_domain_ops = {
 
 static void mc_read_resources(device_t dev)
 {
-	struct resource *resource;
+	u32 pcie_config_base;
+	int buses;
 
 	pci_dev_read_resources(dev);
 
-	/* So, this is one of the big mysteries in the coreboot resource
-	 * allocator. This resource should make sure that the address space
-	 * of the PCIe memory mapped config space bar. But it does not.
-	 */
-
 	/* We use 0xcf as an unused index for our PCIe bar so that we find it again */
-	resource = new_resource(dev, 0xcf);
-	resource->base = DEFAULT_PCIEXBAR;
-	resource->size = 64 * 1024 * 1024;	/* 64MB hard coded PCIe config space */
-	resource->flags =
-	    IORESOURCE_MEM | IORESOURCE_FIXED | IORESOURCE_STORED |
-	    IORESOURCE_ASSIGNED;
-	printk(BIOS_DEBUG, "Adding PCIe enhanced config space BAR 0x%08lx-0x%08lx.\n",
-		     (unsigned long)(resource->base), (unsigned long)(resource->base + resource->size));
+	buses = get_pcie_bar(&pcie_config_base);
+	if (buses) {
+		struct resource *resource = new_resource(dev, 0xcf);
+		mmconf_resource_init(resource, pcie_config_base, buses);
+	}
 }
 
 static void mc_set_resources(device_t dev)
diff --git a/src/northbridge/intel/i3100/northbridge.c b/src/northbridge/intel/i3100/northbridge.c
index 8025ac3cbb..4549f85f4f 100644
--- a/src/northbridge/intel/i3100/northbridge.c
+++ b/src/northbridge/intel/i3100/northbridge.c
@@ -32,9 +32,6 @@
 #include <arch/acpi.h>
 
 
-static u32 max_bus;
-
-
 static void pci_domain_set_resources(device_t dev)
 {
 	device_t mc_dev;
@@ -139,14 +136,9 @@ static struct device_operations pci_domain_ops = {
 
 static void mc_read_resources(device_t dev)
 {
-	struct resource *resource;
-
 	pci_dev_read_resources(dev);
 
-	resource = new_resource(dev, 0xcf);
-	resource->base = 0xe0000000;
-	resource->size = max_bus * 4096*256;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_FIXED | IORESOURCE_STORED |  IORESOURCE_ASSIGNED;
+	mmconf_resource(dev, 0xcf);
 }
 
 static void mc_set_resources(device_t dev)
diff --git a/src/northbridge/intel/i945/northbridge.c b/src/northbridge/intel/i945/northbridge.c
index 5d1859133c..c027bece88 100644
--- a/src/northbridge/intel/i945/northbridge.c
+++ b/src/northbridge/intel/i945/northbridge.c
@@ -27,13 +27,12 @@
 #include <arch/acpi.h>
 #include "i945.h"
 
-static int get_pcie_bar(u32 *base, u32 *len)
+static int get_pcie_bar(u32 *base)
 {
 	device_t dev;
 	u32 pciexbar_reg;
 
 	*base = 0;
-	*len = 0;
 
 	dev = dev_find_slot(0, PCI_DEVFN(0, 0));
 	if (!dev)
@@ -47,36 +46,18 @@ static int get_pcie_bar(u32 *base, u32 *len)
 	switch ((pciexbar_reg >> 1) & 3) {
 	case 0: // 256MB
 		*base = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28));
-		*len = 256 * 1024 * 1024;
-		return 1;
+		return 256;
 	case 1: // 128M
 		*base = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28)|(1 << 27));
-		*len = 128 * 1024 * 1024;
-		return 1;
+		return 128;
 	case 2: // 64M
 		*base = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28)|(1 << 27)|(1 << 26));
-		*len = 64 * 1024 * 1024;
-		return 1;
+		return 64;
 	}
 
 	return 0;
 }
 
-static void add_fixed_resources(struct device *dev, int index)
-{
-	struct resource *resource;
-	u32 pcie_config_base, pcie_config_size;
-
-	if (get_pcie_bar(&pcie_config_base, &pcie_config_size)) {
-		printk(BIOS_DEBUG, "Adding PCIe config bar\n");
-		resource = new_resource(dev, index++);
-		resource->base = (resource_t) pcie_config_base;
-		resource->size = (resource_t) pcie_config_size;
-		resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-	}
-}
-
 static void pci_domain_set_resources(device_t dev)
 {
 	uint32_t pci_tolm;
@@ -153,8 +134,6 @@ static void pci_domain_set_resources(device_t dev)
 	uma_resource(dev, 5, uma_memory_base >> 10, uma_memory_size >> 10);
 	mmio_resource(dev, 6, tseg_memory_base >> 10, tseg_memory_size >> 10);
 
-	add_fixed_resources(dev, 7);
-
 	assign_resources(dev->link_list);
 }
 
@@ -173,19 +152,17 @@ static struct device_operations pci_domain_ops = {
 
 static void mc_read_resources(device_t dev)
 {
-	struct resource *resource;
+	u32 pcie_config_base;
+	int buses;
 
 	pci_dev_read_resources(dev);
 
 	/* We use 0xcf as an unused index for our PCIe bar so that we find it again */
-	resource = new_resource(dev, 0xcf);
-	resource->base = DEFAULT_PCIEXBAR;
-	resource->size = 64 * 1024 * 1024;	/* 64MB hard coded PCIe config space */
-	resource->flags =
-	    IORESOURCE_MEM | IORESOURCE_FIXED | IORESOURCE_STORED |
-	    IORESOURCE_ASSIGNED;
-	printk(BIOS_DEBUG, "Adding PCIe enhanced config space BAR 0x%08lx-0x%08lx.\n",
-		     (unsigned long)(resource->base), (unsigned long)(resource->base + resource->size));
+	buses = get_pcie_bar(&pcie_config_base);
+	if (buses) {
+		struct resource *resource = new_resource(dev, 0xcf);
+		mmconf_resource_init(resource, pcie_config_base, buses);
+	}
 }
 
 static void mc_set_resources(device_t dev)
diff --git a/src/northbridge/intel/nehalem/Kconfig b/src/northbridge/intel/nehalem/Kconfig
index 4dada50aaf..884660ad88 100644
--- a/src/northbridge/intel/nehalem/Kconfig
+++ b/src/northbridge/intel/nehalem/Kconfig
@@ -24,6 +24,10 @@ config NORTHBRIDGE_INTEL_NEHALEM
 
 if NORTHBRIDGE_INTEL_NEHALEM
 
+config MMCONF_BUS_NUMBER
+	int
+	default 256
+
 config CBFS_SIZE
 	hex
 	default 0x100000
diff --git a/src/northbridge/intel/nehalem/northbridge.c b/src/northbridge/intel/nehalem/northbridge.c
index 06c0a9655b..779e49cd54 100644
--- a/src/northbridge/intel/nehalem/northbridge.c
+++ b/src/northbridge/intel/nehalem/northbridge.c
@@ -69,11 +69,6 @@ static void add_fixed_resources(struct device *dev, int index)
 	   0xfed1c000-0xfed20000 RCBA
 	   0xfed90000-0xfed94000 IOMMU
 	   0xff800000-0xffffffff ROM. */
-	resource = new_resource(dev, index++);
-	resource->base = (resource_t) 0xe0000000;
-	resource->size = (resource_t) 0x10000000;
-	resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-	  IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
 
 	resource = new_resource(dev, index++);
 	resource->base = (resource_t) 0xfed00000;
@@ -98,10 +93,6 @@ static void pci_domain_set_resources(device_t dev)
 	assign_resources(dev->link_list);
 }
 
-	/* TODO We could determine how many PCIe busses we need in
-	 * the bar. For now that number is hardcoded to a max of 64.
-	 * See e7525/northbridge.c for an example.
-	 */
 static struct device_operations pci_domain_ops = {
 	.read_resources = pci_domain_read_resources,
 	.set_resources = pci_domain_set_resources,
@@ -119,6 +110,8 @@ static void mc_read_resources(device_t dev)
 
 	pci_dev_read_resources(dev);
 
+	mmconf_resource(dev, 0x50);
+
 	tseg_base = pci_read_config32(dev_find_slot(0, PCI_DEVFN(0, 0)), TSEG);
 	TOUUD = pci_read_config16(dev_find_slot(0, PCI_DEVFN(0, 0)),
 				  D0F0_TOUUD);
diff --git a/src/northbridge/intel/sandybridge/northbridge.c b/src/northbridge/intel/sandybridge/northbridge.c
index fe1a07c570..7f7c842324 100644
--- a/src/northbridge/intel/sandybridge/northbridge.c
+++ b/src/northbridge/intel/sandybridge/northbridge.c
@@ -61,13 +61,12 @@ int bridge_silicon_revision(void)
 static const int legacy_hole_base_k = 0xa0000 / 1024;
 static const int legacy_hole_size_k = 384;
 
-static int get_pcie_bar(u32 *base, u32 *len)
+static int get_pcie_bar(u32 *base)
 {
 	device_t dev;
 	u32 pciexbar_reg;
 
 	*base = 0;
-	*len = 0;
 
 	dev = dev_find_slot(0, PCI_DEVFN(0, 0));
 	if (!dev)
@@ -81,16 +80,13 @@ static int get_pcie_bar(u32 *base, u32 *len)
 	switch ((pciexbar_reg >> 1) & 3) {
 	case 0: // 256MB
 		*base = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28));
-		*len = 256 * 1024 * 1024;
-		return 1;
+		return 256;
 	case 1: // 128M
 		*base = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28)|(1 << 27));
-		*len = 128 * 1024 * 1024;
-		return 1;
+		return 128;
 	case 2: // 64M
 		*base = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28)|(1 << 27)|(1 << 26));
-		*len = 64 * 1024 * 1024;
-		return 1;
+		return 64;
 	}
 
 	return 0;
@@ -98,21 +94,8 @@ static int get_pcie_bar(u32 *base, u32 *len)
 
 static void add_fixed_resources(struct device *dev, int index)
 {
-	struct resource *resource;
-	u32 pcie_config_base, pcie_config_size;
-
 	mmio_resource(dev, index++, uma_memory_base >> 10, uma_memory_size >> 10);
 
-	if (get_pcie_bar(&pcie_config_base, &pcie_config_size)) {
-		printk(BIOS_DEBUG, "Adding PCIe config bar base=0x%08x "
-		       "size=0x%x\n", pcie_config_base, pcie_config_size);
-		resource = new_resource(dev, index++);
-		resource->base = (resource_t) pcie_config_base;
-		resource->size = (resource_t) pcie_config_size;
-		resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-	}
-
 	mmio_resource(dev, index++, legacy_hole_base_k,
 			(0xc0000 >> 10) - legacy_hole_base_k);
 	reserved_ram_resource(dev, index++, 0xc0000 >> 10,
@@ -276,24 +259,17 @@ static struct device_operations pci_domain_ops = {
 
 static void mc_read_resources(device_t dev)
 {
-	struct resource *resource;
+	u32 pcie_config_base;
+	int buses;
 
 	pci_dev_read_resources(dev);
 
-	/* So, this is one of the big mysteries in the coreboot resource
-	 * allocator. This resource should make sure that the address space
-	 * of the PCIe memory mapped config space bar. But it does not.
-	 */
-
 	/* We use 0xcf as an unused index for our PCIe bar so that we find it again */
-	resource = new_resource(dev, 0xcf);
-	resource->base = DEFAULT_PCIEXBAR;
-	resource->size = 64 * 1024 * 1024;	/* 64MB hard coded PCIe config space */
-	resource->flags =
-	    IORESOURCE_MEM | IORESOURCE_FIXED | IORESOURCE_STORED |
-	    IORESOURCE_ASSIGNED;
-	printk(BIOS_DEBUG, "Adding PCIe enhanced config space BAR 0x%08lx-0x%08lx.\n",
-		     (unsigned long)(resource->base), (unsigned long)(resource->base + resource->size));
+	buses = get_pcie_bar(&pcie_config_base);
+	if (buses) {
+		struct resource *resource = new_resource(dev, 0xcf);
+		mmconf_resource_init(resource, pcie_config_base, buses);
+	}
 }
 
 static void mc_set_resources(device_t dev)
diff --git a/src/northbridge/via/vx900/Kconfig b/src/northbridge/via/vx900/Kconfig
index 73d40adfba..4b1e6cc4cd 100644
--- a/src/northbridge/via/vx900/Kconfig
+++ b/src/northbridge/via/vx900/Kconfig
@@ -33,6 +33,10 @@ config MMCONF_BASE_ADDRESS
 	hex
 	default 0xe0000000
 
+config MMCONF_BUS_NUMBER
+	int
+	default 256
+
 config VGA_BIOS_ID
 	string
 	default "1106,7122"
diff --git a/src/northbridge/via/vx900/northbridge.c b/src/northbridge/via/vx900/northbridge.c
index a4a8ecec48..7429c4f973 100644
--- a/src/northbridge/via/vx900/northbridge.c
+++ b/src/northbridge/via/vx900/northbridge.c
@@ -297,10 +297,7 @@ static void vx900_read_resources(device_t dev)
 	/* Now do the same for our MMCONF
 	 * We always run with MMCONF enabled. We need to access the extended
 	 * config space when configuring PCI-Express links */
-	res = new_resource(dev, idx++);
-	res->size = 256 * MiB;
-	res->base = CONFIG_MMCONF_BASE_ADDRESS;
-	res->flags = IORESOURCE_MEM | IORESOURCE_ASSIGNED | IORESOURCE_FIXED;
+	mmconf_resource(dev, idx++);
 
 	pci_domain_read_resources(dev);
 }
diff --git a/src/soc/intel/fsp_baytrail/northcluster.c b/src/soc/intel/fsp_baytrail/northcluster.c
index bf1a3881b0..b4aceeeba7 100644
--- a/src/soc/intel/fsp_baytrail/northcluster.c
+++ b/src/soc/intel/fsp_baytrail/northcluster.c
@@ -86,13 +86,12 @@ uint32_t nc_read_top_of_low_memory(void)
 	return fsp_mem_base;
 }
 
-static int get_pcie_bar(u32 *base, u32 *len)
+static int get_pcie_bar(u32 *base)
 {
 	device_t dev;
 	u32 pciexbar_reg;
 
 	*base = 0;
-	*len = 0;
 
 	dev = dev_find_slot(0, PCI_DEVFN(0, 0));
 	if (!dev)
@@ -105,26 +104,13 @@ static int get_pcie_bar(u32 *base, u32 *len)
 
 	*base = pciexbar_reg & ((1 << 31) | (1 << 30) | (1 << 29) |
 				(1 << 28));
-	*len = 256 * 1024 * 1024; /* 256MB ECAM range */
-	return 1;
+	return 256;
 
 }
 
 static int add_fixed_resources(struct device *dev, int index)
 {
 	struct resource *resource;
-	u32 pcie_config_base, pcie_config_size;
-
-
-	if (get_pcie_bar(&pcie_config_base, &pcie_config_size)) {
-		printk(BIOS_DEBUG, "Adding PCIe config bar base=0x%08x "
-		       "size=0x%x\n", pcie_config_base, pcie_config_size);
-		resource = new_resource(dev, index++);
-		resource->base = (resource_t) pcie_config_base;
-		resource->size = (resource_t) pcie_config_size;
-		resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-	}
 
 	resource = new_resource(dev, index++); /* Local APIC */
 	resource->base = LAPIC_DEFAULT_BASE;
@@ -182,9 +168,18 @@ static void mc_add_dram_resources(device_t dev)
 
 static void nc_read_resources(device_t dev)
 {
+	u32 pcie_config_base;
+	int buses;
+
 	/* Call the normal read_resources */
 	pci_dev_read_resources(dev);
 
+	/* We use 0xcf as an unused index for our PCIe bar so that we find it again */
+	buses = get_pcie_bar(&pcie_config_base);
+	if (buses) {
+		struct resource *resource = new_resource(dev, 0xcf);
+		mmconf_resource_init(resource, pcie_config_base, buses);
+	}
 
 	/* Calculate and add DRAM resources. */
 	mc_add_dram_resources(dev);
diff --git a/src/soc/intel/sch/northbridge.c b/src/soc/intel/sch/northbridge.c
index 390a0bcb2e..2d3949052c 100644
--- a/src/soc/intel/sch/northbridge.c
+++ b/src/soc/intel/sch/northbridge.c
@@ -27,7 +27,7 @@
 #include <arch/acpi.h>
 #include "sch.h"
 
-static int get_pcie_bar(u32 *base, u32 *len)
+static int get_pcie_bar(u32 *base)
 {
 	device_t dev;
 	u32 pciexbar_reg;
@@ -50,18 +50,15 @@ static int get_pcie_bar(u32 *base, u32 *len)
 	case 0:	/* 256MB */
 		*base = pciexbar_reg & ((1 << 31) | (1 << 30) | (1 << 29) |
 					(1 << 28));
-		*len = 256 * 1024 * 1024;
-		return 1;
+		return 256;
 	case 1: /* 128M */
 		*base = pciexbar_reg & ((1 << 31) | (1 << 30) | (1 << 29) |
 					(1 << 28) | (1 << 27));
-		*len = 128 * 1024 * 1024;
-		return 1;
+		return 128;
 	case 2: /* 64M */
 		*base = pciexbar_reg & ((1 << 31) | (1 << 30) | (1 << 29) |
 					(1 << 28) | (1 << 27) | (1 << 26));
-		*len = 64 * 1024 * 1024;
-		return 1;
+		return 64;
 	}
 
 	return 0;
@@ -70,16 +67,6 @@ static int get_pcie_bar(u32 *base, u32 *len)
 static void add_fixed_resources(struct device *dev, int index)
 {
 	struct resource *resource;
-	u32 pcie_config_base, pcie_config_size;
-
-	if (get_pcie_bar(&pcie_config_base, &pcie_config_size)) {
-		printk(BIOS_DEBUG, "Adding PCIe config bar\n");
-		resource = new_resource(dev, index++);
-		resource->base = (resource_t) pcie_config_base;
-		resource->size = (resource_t) pcie_config_size;
-		resource->flags = IORESOURCE_MEM | IORESOURCE_RESERVE |
-		    IORESOURCE_FIXED | IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-	}
 
 	printk(BIOS_DEBUG, "Adding CMC shadow area\n");
 	resource = new_resource(dev, index++);
@@ -198,28 +185,20 @@ static struct device_operations pci_domain_ops = {
 
 static void mc_read_resources(device_t dev)
 {
-	struct resource *resource;
+	u32 pcie_config_base;
+	int buses;
 
 	pci_dev_read_resources(dev);
 
-	/*
-	 * So, this is one of the big mysteries in the coreboot resource
-	 * allocator. This resource should make sure that the address space
-	 * of the PCIe memory mapped config space bar. But it does not.
-	 */
-
 	/*
 	 * We use 0xcf as an unused index for our PCIe bar so that we find
 	 * it again.
 	 */
-	resource = new_resource(dev, 0xcf);
-	resource->flags = IORESOURCE_MEM | IORESOURCE_FIXED |
-			  IORESOURCE_STORED | IORESOURCE_ASSIGNED;
-	get_pcie_bar((u32 *)&resource->base, (u32 *)&resource->size);
-	printk(BIOS_DEBUG,
-	       "Adding PCIe enhanced config space BAR 0x%08lx-0x%08lx.\n",
-	       (unsigned long)(resource->base),
-	       (unsigned long)(resource->base + resource->size));
+	buses = get_pcie_bar(&pcie_config_base);
+	if (buses) {
+		struct resource *resource = new_resource(dev, 0xcf);
+		mmconf_resource_init(resource, pcie_config_base, buses);
+	}
 }
 
 static void mc_set_resources(device_t dev)