x86: allocate space within a region top-down

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>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 922b5a1f978b899f55bfed0611f4b6456482a124..0fe76df866dbf7c545cc1e9ba488e9cd855a9b73 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -788,6 +788,7 @@ void __init setup_arch(char **cmdline_p)
 
        x86_init.oem.arch_setup();
 
+       resource_alloc_from_bottom = 0;
        iomem_resource.end = (1ULL << boot_cpu_data.x86_phys_bits) - 1;
        setup_memory_map();
        parse_setup_data();