1 files changed, 36 insertions, 1 deletions

diff --git a/include/asm-x86/e820.h b/include/asm-x86/e820.h
index 65c891d2a4cb..ab18457a95c0 100644
--- a/include/asm-x86/e820.h
+++ b/include/asm-x86/e820.h
@@ -2,6 +2,41 @@
 #define __ASM_E820_H
 #define E820MAP 0x2d0           /* our map */
 #define E820MAX 128             /* number of entries in E820MAP */
+
+/*
+ * Legacy E820 BIOS limits us to 128 (E820MAX) nodes due to the
+ * constrained space in the zeropage.  If we have more nodes than
+ * that, and if we've booted off EFI firmware, then the EFI tables
+ * passed us from the EFI firmware can list more nodes.  Size our
+ * internal memory map tables to have room for these additional
+ * nodes, based on up to three entries per node for which the
+ * kernel was built: MAX_NUMNODES == (1 << CONFIG_NODES_SHIFT),
+ * plus E820MAX, allowing space for the possible duplicate E820
+ * entries that might need room in the same arrays, prior to the
+ * call to sanitize_e820_map() to remove duplicates.  The allowance
+ * of three memory map entries per node is "enough" entries for
+ * the initial hardware platform motivating this mechanism to make
+ * use of additional EFI map entries.  Future platforms may want
+ * to allow more than three entries per node or otherwise refine
+ * this size.
+ */
+
+/*
+ * Odd: 'make headers_check' complains about numa.h if I try
+ * to collapse the next two #ifdef lines to a single line:
+ *      #if defined(__KERNEL__) && defined(CONFIG_EFI)
+ */
+#ifdef __KERNEL__
+#ifdef CONFIG_EFI
+#include <linux/numa.h>
+#define E820_X_MAX (E820MAX + 3 * MAX_NUMNODES)
+#else   /* ! CONFIG_EFI */
+#define E820_X_MAX E820MAX
+#endif
+#else   /* ! __KERNEL__ */
+#define E820_X_MAX E820MAX
+#endif
+
 #define E820NR  0x1e8           /* # entries in E820MAP */
 
 #define E820_RAM        1
@@ -18,7 +53,7 @@ struct e820entry {
 
 struct e820map {
         __u32 nr_map;
-        struct e820entry map[E820MAX];
+        struct e820entry map[E820_X_MAX];
 };
 
 extern struct e820map e820;