diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 87a1733..71d05f4 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1189,8 +1189,6 @@
 				Mechanism 2.
 		nommconf	[IA-32,X86_64] Disable use of MMCONFIG for PCI
 				Configuration
-		mmconf		[IA-32,X86_64] Force MMCONFIG. This is useful
-				to override the builtin blacklist.
 		nomsi		[MSI] If the PCI_MSI kernel config parameter is
 				enabled, this kernel boot option can be used to
 				disable the use of MSI interrupts system-wide.
diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index 345ffb7..f168220 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -956,6 +956,38 @@
 	return 0;
 }
 
+ /*
+  * This function checks if the entire range <start,end> is mapped with type.
+  *
+  * Note: this function only works correct if the e820 table is sorted and
+  * not-overlapping, which is the case
+  */
+int __init
+e820_all_mapped(unsigned long s, unsigned long e, unsigned type)
+{
+	u64 start = s;
+	u64 end = e;
+	int i;
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i];
+		if (type && ei->type != type)
+			continue;
+		/* is the region (part) in overlap with the current region ?*/
+		if (ei->addr >= end || ei->addr + ei->size <= start)
+			continue;
+		/* if the region is at the beginning of <start,end> we move
+		 * start to the end of the region since it's ok until there
+		 */
+		if (ei->addr <= start)
+			start = ei->addr + ei->size;
+		/* if start is now at or beyond end, we're done, full
+		 * coverage */
+		if (start >= end)
+			return 1; /* we're done */
+	}
+	return 0;
+}
+
 /*
  * Find the highest page frame number we have available
  */
diff --git a/arch/i386/pci/common.c b/arch/i386/pci/common.c
index 1220dd8..0a362e3 100644
--- a/arch/i386/pci/common.c
+++ b/arch/i386/pci/common.c
@@ -237,11 +237,6 @@
 		pci_probe &= ~PCI_PROBE_MMCONF;
 		return NULL;
 	}
-	/* override DMI blacklist */
-	else if (!strcmp(str, "mmconf")) {
-		pci_probe |= PCI_PROBE_MMCONF_FORCE;
-		return NULL;
-	}
 #endif
 	else if (!strcmp(str, "noacpi")) {
 		acpi_noirq_set();
diff --git a/arch/i386/pci/mmconfig.c b/arch/i386/pci/mmconfig.c
index ef5a2fa..972180f 100644
--- a/arch/i386/pci/mmconfig.c
+++ b/arch/i386/pci/mmconfig.c
@@ -12,7 +12,6 @@
 #include <linux/pci.h>
 #include <linux/init.h>
 #include <linux/acpi.h>
-#include <linux/dmi.h>
 #include <asm/e820.h>
 #include "pci.h"
 
@@ -188,31 +187,9 @@
 	}
 }
 
-static int disable_mcfg(struct dmi_system_id *d)
-{
-	printk("PCI: %s detected. Disabling MCFG.\n", d->ident);
-	pci_probe &= ~PCI_PROBE_MMCONF;
-	return 0;
-}
-
-static struct dmi_system_id __initdata dmi_bad_mcfg[] = {
-	/* Has broken MCFG table that makes the system hang when used */
-        {
-         .callback = disable_mcfg,
-         .ident = "Intel D3C5105 SDV",
-         .matches = {
-                     DMI_MATCH(DMI_BIOS_VENDOR, "Intel"),
-                     DMI_MATCH(DMI_BOARD_NAME, "D26928"),
-                     },
-         },
-         {}
-};
-
 void __init pci_mmcfg_init(void)
 {
-	dmi_check_system(dmi_bad_mcfg);
-
-	if ((pci_probe & (PCI_PROBE_MMCONF_FORCE|PCI_PROBE_MMCONF)) == 0)
+	if ((pci_probe & PCI_PROBE_MMCONF) == 0)
 		return;
 
 	acpi_table_parse(ACPI_MCFG, acpi_parse_mcfg);
@@ -221,6 +198,15 @@
 	    (pci_mmcfg_config[0].base_address == 0))
 		return;
 
+	if (!e820_all_mapped(pci_mmcfg_config[0].base_address,
+			pci_mmcfg_config[0].base_address + MMCONFIG_APER_MIN,
+			E820_RESERVED)) {
+		printk(KERN_ERR "PCI: BIOS Bug: MCFG area at %x is not E820-reserved\n",
+				pci_mmcfg_config[0].base_address);
+		printk(KERN_ERR "PCI: Not using MMCONFIG.\n");
+		return;
+	}
+
 	printk(KERN_INFO "PCI: Using MMCONFIG\n");
 	raw_pci_ops = &pci_mmcfg;
 	pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;
diff --git a/arch/i386/pci/pci.h b/arch/i386/pci/pci.h
index 49a849b..bf4e793 100644
--- a/arch/i386/pci/pci.h
+++ b/arch/i386/pci/pci.h
@@ -16,8 +16,7 @@
 #define PCI_PROBE_CONF1		0x0002
 #define PCI_PROBE_CONF2		0x0004
 #define PCI_PROBE_MMCONF	0x0008
-#define PCI_PROBE_MMCONF_FORCE	0x0010
-#define PCI_PROBE_MASK		0x00ff
+#define PCI_PROBE_MASK		0x000f
 
 #define PCI_NO_SORT		0x0100
 #define PCI_BIOS_SORT		0x0200
diff --git a/arch/x86_64/kernel/e820.c b/arch/x86_64/kernel/e820.c
index 764bf23..d6d7f73 100644
--- a/arch/x86_64/kernel/e820.c
+++ b/arch/x86_64/kernel/e820.c
@@ -108,6 +108,35 @@
 	return 0;
 }
 
+/*
+ * This function checks if the entire range <start,end> is mapped with type.
+ *
+ * Note: this function only works correct if the e820 table is sorted and
+ * not-overlapping, which is the case
+ */
+int __init e820_all_mapped(unsigned long start, unsigned long end, unsigned type)
+{
+	int i;
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i];
+		if (type && ei->type != type)
+			continue;
+		/* is the region (part) in overlap with the current region ?*/
+		if (ei->addr >= end || ei->addr + ei->size <= start)
+			continue;
+
+		/* if the region is at the beginning of <start,end> we move
+		 * start to the end of the region since it's ok until there
+		 */
+		if (ei->addr <= start)
+			start = ei->addr + ei->size;
+		/* if start is now at or beyond end, we're done, full coverage */
+		if (start >= end)
+			return 1; /* we're done */
+	}
+	return 0;
+}
+
 /* 
  * Find a free area in a specific range. 
  */ 
diff --git a/arch/x86_64/pci/mmconfig.c b/arch/x86_64/pci/mmconfig.c
index 2d48a79..3c55c76c 100644
--- a/arch/x86_64/pci/mmconfig.c
+++ b/arch/x86_64/pci/mmconfig.c
@@ -9,7 +9,6 @@
 #include <linux/init.h>
 #include <linux/acpi.h>
 #include <linux/bitmap.h>
-#include <linux/dmi.h>
 #include <asm/e820.h>
 
 #include "pci.h"
@@ -165,33 +164,11 @@
 	}
 }
 
-static int disable_mcfg(struct dmi_system_id *d)
-{
-	printk("PCI: %s detected. Disabling MCFG.\n", d->ident);
-	pci_probe &= ~PCI_PROBE_MMCONF;
-	return 0;
-}
-
-static struct dmi_system_id __initdata dmi_bad_mcfg[] = {
-	/* Has broken MCFG table that makes the system hang when used */
-        {
-         .callback = disable_mcfg,
-         .ident = "Intel D3C5105 SDV",
-         .matches = {
-                     DMI_MATCH(DMI_BIOS_VENDOR, "Intel"),
-                     DMI_MATCH(DMI_BOARD_NAME, "D26928"),
-                     },
-         },
-         {}
-};
-
 void __init pci_mmcfg_init(void)
 {
 	int i;
 
-	dmi_check_system(dmi_bad_mcfg);
-
-	if ((pci_probe & (PCI_PROBE_MMCONF|PCI_PROBE_MMCONF_FORCE)) == 0)
+	if ((pci_probe & PCI_PROBE_MMCONF) == 0)
 		return;
 
 	acpi_table_parse(ACPI_MCFG, acpi_parse_mcfg);
@@ -200,6 +177,15 @@
 	    (pci_mmcfg_config[0].base_address == 0))
 		return;
 
+	if (!e820_all_mapped(pci_mmcfg_config[0].base_address,
+			pci_mmcfg_config[0].base_address + MMCONFIG_APER_MIN,
+			E820_RESERVED)) {
+		printk(KERN_ERR "PCI: BIOS Bug: MCFG area at %x is not E820-reserved\n",
+				pci_mmcfg_config[0].base_address);
+		printk(KERN_ERR "PCI: Not using MMCONFIG.\n");
+		return;
+	}
+
 	/* RED-PEN i386 doesn't do _nocache right now */
 	pci_mmcfg_virt = kmalloc(sizeof(*pci_mmcfg_virt) * pci_mmcfg_config_num, GFP_KERNEL);
 	if (pci_mmcfg_virt == NULL) {