Patrick Lidstone
Self-hosted

Operating System Experiments

Development log

Working notes from the operating system projects - what got built, what broke, and what turned out to be harder than it looked. Mostly Path OS bring-up on real hardware at the moment.

The articles in this section describe where each project has reached. This is the running commentary underneath them.

  1. S3 sleep, and the three bugs it found Suspend to RAM is a deal with the firmware - leave an address behind, and be ready to be re-entered as though the machine had just been switched on. Every bug it exposed was somewhere the kernel already was.
  2. A cellular modem in an M.2 slot The X1 has an integral Fibocom L850-GL. I expected to have to write PPP or SLIP for it, and it turned out to want neither.
  3. A self test, a startup sound and a splash screen Audio is working in both directions, verified by playing and recording at the same time. Which means the machine can finally make a noise when it boots.
  4. Bluetooth on the X1, and why isochronous audio is hard Getting a phone onto the machine over Hands-Free Profile, and then getting a call's audio through it in both directions. The second part was much harder than the first.
  5. SMP, and the case for pinning a core Multiprocessing is solid across the eight cores. What is missing is a way to take one of them out of the pool entirely.