Date Added: Jan 2010
What is real-time and how can it be added to a plain vanilla Linux kernel? Two fundamentally different approaches are described here. One approach attempts to patch the vanilla Linux kernel (PREEMPT_RT) to achieve real-time functionality, while the other one utilizes a dual kernel architecture (RTAI, RTLinux/GPL, Xenomai, XM/eRTL, Real-Time Core, XtratuM, seL4, PaRTiKle,...), where Linux runs as the idle process on top of the real-time kernel. How do those approaches compare? At the time the author started his quest for the holy grail of real-time Linux he hoped that it would be a clear decision wether to use p-rt or dk, but things seem to be less black and white than he initially thought.