[PATCH v3 6/6] x86: allocate space within a region top-down

[Bjorn Helgaas <bjorn.helgaas@hp.com>]

Request that allocate_resource() use available space from high addresses
first, rather than the default of using low addresses first.

The most common place this makes a difference is when we move or assign
new PCI device resources.  Low addresses are generally scarce, so it's
better to use high addresses when possible.  This follows Windows practice
for PCI allocation.

Reference: https://bugzilla.kernel.org/show_bug.cgi?id=16228#c42
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
---

 arch/x86/include/asm/io.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)


diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 30a3e97..6cc02c4 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -35,6 +35,7 @@
   */
 
 #define ARCH_HAS_IOREMAP_WC
+#define ARCH_HAS_TOP_DOWN_ALLOC
 
 #include <linux/string.h>
 #include <linux/compiler.h>