There are many approaches to describing an OS kernel. I have tried many and the papers about other systems try many more. Reading some of these papers often leads me to try describing Keykos in parallel to those other papers. Here is a start.
QNX, Symbian, Keykos Mach and Aegis, Coyotos,
EROS, Coyotos, CapROS
Shap’s note