[PATCH] x86: Revert e820 MCFG heuristics

The check for the MCFG table being reserved in the e820 map was originally
added to detect a broken BIOS in a preproduction Intel SDV. However it also
breaks the Apple x86 Macs, which can't supply this properly, but need
a working MCFG. With this patch they wouldn't use the MCFG and not work.

After some discussion I think it's best to remove the heuristic again.
It also failed on some other boxes (although it didn't cause much
problems there because old style port access for PCI config space
still works as fallback), but the preproduction SDVs can just use
pci=nommcfg. Supporting production machines properly is more
important.

Edgar Hucek did all the debugging work.

Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Edgar Hucek <hostmaster@ed-soft.at>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 0 insertions, 9 deletions

diff --git a/arch/x86_64/pci/mmconfig.c b/arch/x86_64/pci/mmconfig.c
index 3c55c76c6fd5..8a4a0f9263ce 100644
--- a/arch/x86_64/pci/mmconfig.c
+++ b/arch/x86_64/pci/mmconfig.c
@@ -177,15 +177,6 @@ void __init pci_mmcfg_init(void)
             (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) {