peteg's blog - hacking - nixie clock - 2010 04 13 RealTime

We have real time.

/hacking/nixie_clock | Link

Finally I have managed to get a real-time Linux kernel running on the ts7250, resulting in a flicker-free display. Score one to patience.

Briefly, the Linux RT blokes skipped 2.6.32.x as the kernel's concurrency foundations got a reworking. They released an RT patch against, and as ynezz has forward-ported the ts72xx patches it was a cinch to move to the bleeding edge. YAFFS (a flash filesystem) broke as it uses some old-school mutexery. Grossly updating it all to the struct mutex way of doing things is straightforward and seems to work.

Hacking the clock driver code is trickier now though, as the process runs at the maximum real-time priority. If it loops without making syscalls, the system dies.