"[...] while the similar lm32 architecture saw a lot of activity in 2010 but does not seem to be actively worked on now [...]"
As part of the Milkymist project we did some serious rework of the lm32 linux port. It now actually works and doesn't crash due to some race conditions after ~3 minutes anymore. It also has device tree support and uses generic code where possible which allowed us to roughly cut the code size for the architecture support in half.
So while Theobroma Systems doesn't really seem to do any work on it anymore, there is still some activity in regards to porting linux to the lm32 architecture.