From 47c561cfa7b3970608543f8f2cb7d08b2d1e0e4d Mon Sep 17 00:00:00 2001
From: Ron Nazarov <ron@noisytoot.org>
Date: Sat, 14 Feb 2026 19:05:18 +0000
Subject: [PATCH 3/4] lib/image.py: Disable $FPT checksum check

I don't actually understand what this does, but it doesn't seem to be
doing anything useful.  It seems to be just checking that some range
of bytes is all zero, which isn't a checksum.

On my OptiPlex 5050 SFF image (which passes), this range of bytes is
empty, because self.data[self.HDRLEN_OFF] is 0.  On my Supermicro
X11SSH-F/LN4F image, self.data[self.HDRLEN_OFF] is 19, which means
that self.data[self.HEADER_OFF:self.data[self.HDRLEN_OFF]] is
bytearray(b'$FP'), which makes the check fail.

Without this check, it can generate a working delta for the Supermicro
X11SSH-F/LN4F.

Change-Id: I16735676fd4ae2a4e065886aeb7a06cead721cdf
Signed-off-by: Ron Nazarov <ron@noisytoot.org>
---
 lib/image.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/image.py b/lib/image.py
index 21db448..e303e8f 100644
--- a/lib/image.py
+++ b/lib/image.py
@@ -84,8 +84,8 @@ class MeImage:
         # Verify magic and checksum
         if self.data[self.MARKER_OFF:self.MARKER_OFF+4] != self.MARKER:
             raise ValueError("Invalid $FPT magic")
-        if sum(self.data[self.HEADER_OFF:self.data[self.HDRLEN_OFF]]) != 0:
-            raise ValueError("Invalid $FPT checksum")
+        # if sum(self.data[self.HEADER_OFF:self.data[self.HDRLEN_OFF]]) != 0:
+        #     raise ValueError("Invalid $FPT checksum")
 
         # Parse entries
         self.entries = {}
-- 
2.52.0

