imgtool: skip erased values in trailer generation
When generating an image with trailer (--pad or --confirm), the
imgtool also adds the erased values into that area. This is not
wanted for flash drivers which use ECC and treat writing erased
values as a real write action, which cannot be overwritten anymore.
See issue #1288
Signed-off-by: Wouter Cappelle <wouter.cappelle@crodeon.com>
diff --git a/scripts/imgtool/image.py b/scripts/imgtool/image.py
index ef5d278..627cc6c 100644
--- a/scripts/imgtool/image.py
+++ b/scripts/imgtool/image.py
@@ -242,15 +242,15 @@
self.save_enctlv,
self.enctlv_len)
trailer_addr = (self.base_addr + self.slot_size) - trailer_size
- padding = bytearray([self.erased_val] *
- (trailer_size - len(self.boot_magic)))
- padding += self.boot_magic
if self.confirm and not self.overwrite_only:
magic_size = 16
magic_align_size = align_up(magic_size, self.max_align)
image_ok_idx = -(magic_align_size + self.max_align)
- padding[image_ok_idx] = 0x01 # image_ok = 0x01
- h.puts(trailer_addr, bytes(padding))
+ flag = bytearray([self.erased_val] * magic_align_size)
+ flag[0] = 0x01 # image_ok = 0x01
+ h.puts(trailer_addr + image_ok_idx, bytes(flag))
+ h.puts(trailer_addr + (trailer_size - len(self.boot_magic)),
+ bytes(self.boot_magic))
h.tofile(path, 'hex')
else:
if self.pad: