README: more details about the format used for the map file

diff --git a/README b/README
index 0c292b2..dc5a0d6 100644 (file)
--- a/README
+++ b/README
@@ -6,9 +6,18 @@ or to split a raw flash dump into its MTD partitions.
 
 The format for describing each memory section in a map file is:
 
-  HexStartingAddres-HexEndingAddress : "name"
+  HexStartingAddress-HexEndingAddress : "name"
 
-just like the output of the MTD driver in linux.
+where HexEndingAddress is actually the address of the byte _after_ the last
+one of the section (HexStartingAddress + size); this is because of how the
+output of the MTD driver in linux is formed (see drivers/mtd/mtdpart.c).
+
+       printk(KERN_NOTICE "0x%012llx-0x%012llx : \"%s\"\n", (unsigned long long)slave->offset,
+               (unsigned long long)(slave->offset + slave->mtd.size), slave->mtd.name);
+
+This is slightly different from the format used in other memory layout files
+(like for instance the one used by flashrom, which specifies the actual end
+address), but it allows to just reuse the output of the linux mtd driver.
 
 Empty lines and lines starting with the '#' character will be ignored
 in the map file.