PCI: add a PCI resource reallocation config option

Add a new config option, PCI_REALLOC_ENABLE_AUTO, which will
automatically try to re-allocate PCI resources if PCI_IOV support is
enabled and the SR-IOV resources are unassigned.  Behavior can still be
controlled using the pci=realloc= parameter.

-v2: According to Jesse, adding one CONFIG option for distribution to
     disable it or enable it.
-v3: update Kconfig text (jbarnes)

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index 37856f7..848bfb8 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -31,6 +31,19 @@
 
 	  When in doubt, say N.
 
+config PCI_REALLOC_ENABLE_AUTO
+	bool "Enable PCI resource re-allocation detection"
+	depends on PCI
+	help
+	  Say Y here if you want the PCI core to detect if PCI resource
+	  re-allocation needs to be enabled. You can always use pci=realloc=on
+          or pci=realloc=off to override it.  Note this feature is a no-op
+          unless PCI_IOV support is also enabled; in that case it will
+          automatically re-allocate PCI resources if SR-IOV BARs have not
+          been allocated by the BIOS.
+
+	  When in doubt, say N.
+
 config PCI_STUB
 	tristate "PCI Stub driver"
 	depends on PCI