1 files changed, 26 insertions, 0 deletions

diff --git a/arch/x86/kernel/e820_32.c b/arch/x86/kernel/e820_32.c
index 4e16ef4a265..80444c5c9b1 100644
--- a/arch/x86/kernel/e820_32.c
+++ b/arch/x86/kernel/e820_32.c
@@ -749,6 +749,32 @@ static int __init parse_memmap(char *arg)
         return 0;
 }
 early_param("memmap", parse_memmap);
+void __init update_memory_range(u64 start, u64 size, unsigned old_type,
+                                unsigned new_type)
+{
+        int i;
+
+        BUG_ON(old_type == new_type);
+
+        for (i = 0; i < e820.nr_map; i++) {
+                struct e820entry *ei = &e820.map[i];
+                u64 final_start, final_end;
+                if (ei->type != old_type)
+                        continue;
+                /* totally covered? */
+                if (ei->addr >= start && ei->size <= size) {
+                        ei->type = new_type;
+                        continue;
+                }
+                /* partially covered */
+                final_start = max(start, ei->addr);
+                final_end = min(start + size, ei->addr + ei->size);
+                if (final_start >= final_end)
+                        continue;
+                add_memory_region(final_start, final_end - final_start,
+                                         new_type);
+        }
+}
 void __init update_e820(void)
 {
         u8 nr_map;