testing

3 posts tagged testing, newest first.

Tagged testing

3 posts
23 Sep 2026
5 min

Breaking dm-verity on purpose: one bit in 52 MB, and the board refuses

The negative test that proves the chain is real: flip a single bit in a 52 MB root filesystem, get `data block 0 is corrupted`, and watch the board refuse. Why you cannot sabotage your own firmware the two obvious ways.

dm-verityembeddedlinuxsecure-bootstm32mp1testing
10 Sep 2026
6 min

Previewing a Scenic UI on the host, with no screen and no board

An hour spent trying to open a window that was never going to be drawn, then the realisation that a Scenic graph is just data. Walking it and rendering to SVG found two layout bugs in a minute that had survived 49 tests and a review.

displayelixirnervesscenicstm32mp1testing
10 Sep 2026
5 min

A drift-free countdown on an STM32MP157F-DK2, tested in milliseconds

Counting down by subtracting the tick interval drifts on an embedded board. Deriving the remaining time from a monotonic deadline instead makes it drift-free by construction — and injecting the clock turns a 25-minute test into a map update. It also caught a real race.

elixirnervesotpstm32mp1testing