Core Memory Shield for Arduino

Re:Core Memory Shield for Arduino by SAI_Peregrinus on Saturday April 27, 2019 @06:30PM (#19768035)

RTAI &/or Xenomai are RTOSes based on Linux, both support ARM. Xenomai has support for the Pi Zero, Pi 2 model B, and Pi 3 Model B[1]. I've never used it, but it's probably easier than porting another OS from scratch.