diff --git a/src/mainboard/google/butterfly/Kconfig b/src/mainboard/google/butterfly/Kconfig
index d41a9f5..be585c7 100644
--- a/src/mainboard/google/butterfly/Kconfig
+++ b/src/mainboard/google/butterfly/Kconfig
@@ -11,7 +11,6 @@
 	select HAVE_ACPI_TABLES
 	select HAVE_OPTION_TABLE
 	select HAVE_ACPI_RESUME
-	select MMCONF_SUPPORT
 	select HAVE_SMI_HANDLER
 	select GFXUMA
 	select CHROMEOS
diff --git a/src/mainboard/google/link/Kconfig b/src/mainboard/google/link/Kconfig
index 4bddc5f..f62d690 100644
--- a/src/mainboard/google/link/Kconfig
+++ b/src/mainboard/google/link/Kconfig
@@ -11,7 +11,6 @@
 	select HAVE_ACPI_TABLES
 	select HAVE_OPTION_TABLE
 	select HAVE_ACPI_RESUME
-	select MMCONF_SUPPORT
 	select HAVE_SMI_HANDLER
 	select GFXUMA
 	select CHROMEOS
diff --git a/src/mainboard/google/parrot/Kconfig b/src/mainboard/google/parrot/Kconfig
index 3081b5a..dbdb5fa 100644
--- a/src/mainboard/google/parrot/Kconfig
+++ b/src/mainboard/google/parrot/Kconfig
@@ -11,7 +11,6 @@
 	select HAVE_ACPI_TABLES
 	select HAVE_OPTION_TABLE
 	select HAVE_ACPI_RESUME
-	select MMCONF_SUPPORT
 	select HAVE_SMI_HANDLER
 	select GFXUMA
 	select CHROMEOS
diff --git a/src/mainboard/google/stout/Kconfig b/src/mainboard/google/stout/Kconfig
index a15d933..a5b7962 100644
--- a/src/mainboard/google/stout/Kconfig
+++ b/src/mainboard/google/stout/Kconfig
@@ -11,7 +11,6 @@
 	select HAVE_ACPI_TABLES
 	select HAVE_OPTION_TABLE
 	select HAVE_ACPI_RESUME
-	select MMCONF_SUPPORT
 	select HAVE_SMI_HANDLER
 	select GFXUMA
 	select CHROMEOS
diff --git a/src/mainboard/intel/emeraldlake2/Kconfig b/src/mainboard/intel/emeraldlake2/Kconfig
index 20685f3..786e9a8 100644
--- a/src/mainboard/intel/emeraldlake2/Kconfig
+++ b/src/mainboard/intel/emeraldlake2/Kconfig
@@ -11,7 +11,6 @@
 	select HAVE_ACPI_TABLES
 	select HAVE_OPTION_TABLE
 	select HAVE_ACPI_RESUME
-	select MMCONF_SUPPORT
 	select GFXUMA
 	#select CHROMEOS
 	select EXTERNAL_MRC_BLOB
diff --git a/src/mainboard/kontron/ktqm77/Kconfig b/src/mainboard/kontron/ktqm77/Kconfig
index dafc959..97d8e5c 100644
--- a/src/mainboard/kontron/ktqm77/Kconfig
+++ b/src/mainboard/kontron/ktqm77/Kconfig
@@ -12,7 +12,6 @@
 	select HAVE_ACPI_TABLES
 	select HAVE_OPTION_TABLE
 	select HAVE_ACPI_RESUME
-	select MMCONF_SUPPORT
 	select HAVE_SMI_HANDLER
 	select GFXUMA
 	select EXTERNAL_MRC_BLOB
diff --git a/src/mainboard/samsung/lumpy/Kconfig b/src/mainboard/samsung/lumpy/Kconfig
index a169726..1c18ec2 100644
--- a/src/mainboard/samsung/lumpy/Kconfig
+++ b/src/mainboard/samsung/lumpy/Kconfig
@@ -12,7 +12,6 @@
 	select HAVE_ACPI_RESUME
 	select HAVE_ACPI_TABLES
 	select HAVE_OPTION_TABLE
-	select MMCONF_SUPPORT
 	select NORTHBRIDGE_INTEL_SANDYBRIDGE
 	select SOUTHBRIDGE_INTEL_BD82X6X
 	select SUPERIO_SMSC_MEC1308
diff --git a/src/mainboard/samsung/stumpy/Kconfig b/src/mainboard/samsung/stumpy/Kconfig
index fa7d03d..f4df8a9 100644
--- a/src/mainboard/samsung/stumpy/Kconfig
+++ b/src/mainboard/samsung/stumpy/Kconfig
@@ -11,7 +11,6 @@
 	select HAVE_ACPI_RESUME
 	select HAVE_ACPI_TABLES
 	select HAVE_OPTION_TABLE
-	select MMCONF_SUPPORT
 	select NORTHBRIDGE_INTEL_SANDYBRIDGE
 	select SOUTHBRIDGE_INTEL_BD82X6X
 	select SUPERIO_ITE_IT8772F
diff --git a/src/northbridge/intel/sandybridge/Kconfig b/src/northbridge/intel/sandybridge/Kconfig
index 3a65782..59b6187 100644
--- a/src/northbridge/intel/sandybridge/Kconfig
+++ b/src/northbridge/intel/sandybridge/Kconfig
@@ -20,11 +20,15 @@
 config NORTHBRIDGE_INTEL_SANDYBRIDGE
 	bool
 	select CACHE_MRC_BIN
+	select MMCONF_SUPPORT
+	select MMCONF_SUPPORT_DEFAULT
 	select CPU_INTEL_MODEL_206AX
 
 config NORTHBRIDGE_INTEL_IVYBRIDGE
 	bool
 	select CACHE_MRC_BIN
+	select MMCONF_SUPPORT
+	select MMCONF_SUPPORT_DEFAULT
 	select CPU_INTEL_MODEL_306AX
 
 if NORTHBRIDGE_INTEL_SANDYBRIDGE
@@ -103,6 +107,10 @@
 
 if NORTHBRIDGE_INTEL_SANDYBRIDGE || NORTHBRIDGE_INTEL_IVYBRIDGE
 
+config BOOTBLOCK_NORTHBRIDGE_INIT
+	string
+	default "northbridge/intel/sandybridge/bootblock.c"
+
 config DCACHE_RAM_MRC_VAR_SIZE
 	hex
 	default 0x4000
diff --git a/src/northbridge/intel/sandybridge/bootblock.c b/src/northbridge/intel/sandybridge/bootblock.c
new file mode 100644
index 0000000..1c1d492
--- /dev/null
+++ b/src/northbridge/intel/sandybridge/bootblock.c
@@ -0,0 +1,26 @@
+#include <arch/io.h>
+
+/* Just re-define this instead of including sandybridge.h. It blows up romcc. */
+#define PCIEXBAR	0x60
+
+static void bootblock_northbridge_init(void)
+{
+	uint32_t reg;
+
+	/*
+	 * The "io" variant of the config access is explicitly used to
+	 * setup the PCIEXBAR because CONFIG_MMCONF_SUPPORT_DEFAULT is set to
+	 * to true. That way all subsequent non-explicit config accesses use
+	 * MCFG. This code also assumes that bootblock_northbridge_init() is
+	 * the first thing called in the non-asm boot block code. The final
+	 * assumption is that no assembly code is using the
+	 * CONFIG_MMCONF_SUPPORT_DEFAULT option to do PCI config acceses.
+	 *
+	 * The PCIEXBAR is assumed to live in the memory mapped IO space under
+	 * 4GiB.
+	 */
+	reg = 0;
+	pci_io_write_config32(PCI_DEV(0,0,0), PCIEXBAR + 4, reg);
+	reg = CONFIG_MMCONF_BASE_ADDRESS | 4 | 1; /* 64MiB - 0-63 buses. */
+	pci_io_write_config32(PCI_DEV(0,0,0), PCIEXBAR, reg);
+}
diff --git a/src/northbridge/intel/sandybridge/early_init.c b/src/northbridge/intel/sandybridge/early_init.c
index c2d4909..583385b 100644
--- a/src/northbridge/intel/sandybridge/early_init.c
+++ b/src/northbridge/intel/sandybridge/early_init.c
@@ -49,8 +49,6 @@
 	pci_write_config32(PCI_DEV(0, 0x00, 0), EPBAR + 4, (0LL+DEFAULT_EPBAR) >> 32);
 	pci_write_config32(PCI_DEV(0, 0x00, 0), MCHBAR, DEFAULT_MCHBAR | 1);
 	pci_write_config32(PCI_DEV(0, 0x00, 0), MCHBAR + 4, (0LL+DEFAULT_MCHBAR) >> 32);
-	pci_write_config32(PCI_DEV(0, 0x00, 0), PCIEXBAR, DEFAULT_PCIEXBAR | 5); /* 64MB - busses 0-63 */
-	pci_write_config32(PCI_DEV(0, 0x00, 0), PCIEXBAR + 4, (0LL+DEFAULT_PCIEXBAR) >> 32);
 	pci_write_config32(PCI_DEV(0, 0x00, 0), DMIBAR, DEFAULT_DMIBAR | 1);
 	pci_write_config32(PCI_DEV(0, 0x00, 0), DMIBAR + 4, (0LL+DEFAULT_DMIBAR) >> 32);