Found on the first real-hardware flash (PM3 Easy). The fullimage ELF has two
adjacent PT_LOAD segments (seg1 ends at 0x15E5AC, seg2 starts there) that share
the 0x15E400 flash page. build_blocks aligned each segment independently, so the
shared page was written twice — seg2's 0xFF-padded head, written last,
erase-programmed the page and wiped seg1's real bytes there (the SAM7 programs a
whole page atomically). That region holds version_information, so the flashed OS
booted but reported 'Missing/Invalid version information'.
Fix: merge segments whose block-aligned spans touch into one buffer, so every
shared page is written once with both segments' real data; 0xFF only fills gaps
and aligned outer edges. Re-flash verified on hardware: 3df2ed2e8 -> 303bd5873,
valid version, matches_pin true. Bootrom untouched throughout (fullimage-only).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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