Modifying the kernel using Xenomai

Because it's a magic spell handed down from Gandalf the Grey, this recipe will only work by saying it aloud three times fast: Xenomai, Xenomai, Xenomai! All right. It sounds like an incantation. But, unfortunately, it's only a software layer on top of a kernel.

The good news, however, is that adding Xenomai to the kernel mix can magically bring real-time(ish) oomph to our BeagleBone Black. So, what is it exactly? It is a set of patches bringing several useful ingredients:

• Real-time support from the hardware interrupt level to user space applications.

• A dual-kernel mix composed of the primary Linux kernel and the secondary Xenomai kernel.

• A subsystem underneath Linux that does not rely on the kernel to pre-empt designated events (like our previous method).

But why should we use it instead of PREEMPT_RT? With its focus on embedded systems, Xenomai is useful for several reasons:

• Lowers system overheads.

• Legacy porting: Easier to port legacy real-time systems. As...