4.4.1. Can Linux handle real-time requirements?

• Linux is multiuser, timesharing system

• Kernels up until 2.4 are not preemptible (2.5 started to integrate low latency and kernel preemption patches)

• The current 2.6 kernels include major parts of the rt-reempt patchset but still no hard real-time.

• Alternatives are
  1. rt-preempt patch
  2. Dual kernel approach
     • RTAI (Paolo Montegazza) is GPLd
     • Xenomai
     • RT-Linux (Victor Yodaiken FSM Labs) is patented . Not clear if patent would stand up in court.

• Two-level structure is faster but more complicated