srat, x86: add support for nodes spanning other nodes

For example, If the physical address layout on a two node system with 8 GB
memory is something like:
node 0: 0-2GB, 4-6GB
node 1: 2-4GB, 6-8GB

Current kernels fail to boot/detect this NUMA topology.

ACPI SRAT tables can expose such a topology which needs to be supported.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 2a59dbb28248..07cf77113565 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -903,6 +903,15 @@ config X86_64_ACPI_NUMA
         help
           Enable ACPI SRAT based node topology detection.
 
+# Some NUMA nodes have memory ranges that span
+# other nodes.  Even though a pfn is valid and
+# between a node's start and end pfns, it may not
+# reside on that node.  See memmap_init_zone()
+# for details.
+config NODES_SPAN_OTHER_NODES
+        def_bool y
+        depends on X86_64_ACPI_NUMA
+
 config NUMA_EMU
         bool "NUMA emulation"
         depends on X86_64 && NUMA