x86/PCI: use host bridge _CRS info by default on 2008 and newer machines

The main benefit of using ACPI host bridge window information is that
we can do better resource allocation in systems with multiple host bridges,
e.g., http://bugzilla.kernel.org/show_bug.cgi?id=14183

Sometimes we need _CRS information even if we only have one host bridge,
e.g., https://bugs.launchpad.net/ubuntu/+source/linux/+bug/341681

Most of these systems are relatively new, so this patch turns on
"pci=use_crs" only on machines with a BIOS date of 2008 or newer.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
index b4bf9a942ed0..05b58ccb2e82 100644
--- a/arch/x86/include/asm/pci_x86.h
+++ b/arch/x86/include/asm/pci_x86.h
@@ -29,6 +29,7 @@
 #define PCI_CHECK_ENABLE_AMD_MMCONF     0x20000
 #define PCI_HAS_IO_ECS          0x40000
 #define PCI_NOASSIGN_ROMS       0x80000
+#define PCI_ROOT_NO_CRS         0x100000
 
 extern unsigned int pci_probe;
 extern unsigned long pirq_table_addr;