1 files changed, 31 insertions, 0 deletions
diff --git a/arch/x86_64/kernel/e820.c b/arch/x86_64/kernel/e820.c
index 9d67955bbc31..4651fd22b213 100644
--- a/arch/x86_64/kernel/e820.c
+++ b/arch/x86_64/kernel/e820.c
@@ -191,6 +191,37 @@ unsigned long __init e820_end_of_ram(void)
 }
 
 /*
+ * Find the hole size in the range.
+ */
+unsigned long __init e820_hole_size(unsigned long start, unsigned long end)
+{
+	unsigned long ram = 0;
+	int i;
+
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i];
+		unsigned long last, addr;
+
+		if (ei->type != E820_RAM ||
+		    ei->addr+ei->size <= start ||
+		    ei->addr >= end)
+			continue;
+
+		addr = round_up(ei->addr, PAGE_SIZE);
+		if (addr < start)
+			addr = start;
+
+		last = round_down(ei->addr + ei->size, PAGE_SIZE);
+		if (last >= end)
+			last = end;
+
+		if (last > addr)
+			ram += last - addr;
+	}
+	return ((end - start) - ram);
+}
+
+/*
  * Mark e820 reserved areas as busy for the resource manager.
  */
 void __init e820_reserve_resources(void)