Not a multi-server operating system. Source: worked on it.
Unless it changed, L4 is used with additional code co-located as the base-band modem on its own cpu. Small RTOS is not a multi-server micro-kernel based os.
I suspect we might be using different meanings of multi-server microkernel OS, unless the modem software is even more limited than I thought - I meant that the system is composed of multiple communicating servers. Does the modem just have few independent colocated "big" servers (like the ancient 4.2 BSD server for Mach)?
EDIT: Also, had some fun in the past learning about the modem software on Qualcomm modems, back before iPhone or Android so nice to meet someone who worked on it :)
Unless it changed, L4 is used with additional code co-located as the base-band modem on its own cpu. Small RTOS is not a multi-server micro-kernel based os.