Thank you for the suggestion.
First, I want to elaborate on the application. I want to try to build a walking robot. The robot inputs are video camera (MIPI_CSI), accelerometers, gyros and force sensors (strain gauges) on the links. The outputs are control signals to tubular motors. I sample the sensors, and perform two algorithms: one for motion control, and one for Localization and Mapping (kind of SLAM). I can suffer 100-150ms processing delay, but the output and inputs have to be done with precise intervals.
Second, I saw Linaro Stable Kernel with RT patch in the following link (https://wiki.linaro.org/LSK). If you say, that Linaro does not provide RT, then I do not understand what these kernels are for.
Regarding the Xenomai. I am not familiar with Real Time OS. In two times I had to implement RT algorithm, I did it on bare metal (Netduino and SHARC SC584). It was very simple, only one thread on each core and interrupts, with no scheduler. So, I afraid that relatively esoteric dual-kernel Xenomai entering level is too high, unlike standard Linux program. Also, if RT patch will be accepted by the mainline kernel, it will become de-facto RT standard, which will increase the support and number of available tutorials.
I though if Qualcomm wanted to push it to medical and automotive, it already provided full programming stuck.