CPatch: Optimising OTA Upgrades Through Binary Diffs
summary
CPatch is a binary patch algorithm for Zephyr FOTA that claims single‑step embedded apply with no decompression and constant compile‑time RAM, using a C native Zephyr implementation with constant memory and a Python generator that tries many heuristics and picks the smallest output. It requires reproducible builds and a readable original image, needs a small extra flash slot, and fails on encrypted images. Demo updates three devices and produces 24 kB patch vs 440 kB image (~6%); comparisons show size typically second best vs bsdiff/xdelta/joro diff.
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chapters (12)
- 0:00CPatch and OTA upgrades
- 2:29Problem with full firmware updates
- 6:23Existing binary diff limits
- 8:48CPatch optimizes embedded patching
- 13:42Binary diff encoding challenges
- 17:17CPatch instruction set
- 21:32CPatch efficiency gains
- 24:48CPatch versus other tools
- 27:00CPatch embedded implementation
- 30:13Python patch generation
- 33:47Live CPatch demo
- 38:36Q&A on CPatch
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