[PATCH] x86_64: Introduce e820_all_mapped

Introduce a e820_all_mapped() function which checks if the entire range
<start,end> is mapped with type.

This is done by moving the local start variable to the end of each
known-good region; if at the end of the function the start address is
still before end, there must be a part that's not of the correct type;
otherwise it's a good region.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index eacc3f0a2ea4..8e70894a9f86 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -963,6 +963,36 @@ efi_memory_present_wrapper(unsigned long start, unsigned long end, void *arg)
 	return 0;
 }
 
+ /*
+  * This function checks if the entire range <start,end> is mapped with type.
+  *
+  * Note: this function only works correct if the e820 table is sorted and
+  * not-overlapping, which is the case
+  */
+int __init
+e820_all_mapped(unsigned long start, unsigned long end, unsigned type)
+{
+	int i;
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i];
+		if (type && ei->type != type)
+			continue;
+		/* is the region (part) in overlap with the current region ?*/
+		if (ei->addr >= end || ei->addr + ei->size <= start)
+			continue;
+		/* if the region is at the beginning of <start,end> we move
+		 * start to the end of the region since it's ok until there
+		 */
+		if (ei->addr <= start)
+			start = ei->addr + ei->size;
+		/* if start is now at or beyond end, we're done, full
+		 * coverage */
+		if (start >= end)
+			return 1; /* we're done */
+	}
+	return 0;
+}
+
 /*
  * Find the highest page frame number we have available
  */