Is realtime possible with Linux? Yes, it is. But which Linux derivate should I use? This is the key question to be answered when Linux is going to be used in the automation industry.

The OSADL criteria for realtime Linux are:

• Strong and agile community
• Long term availability
• Ease of use (user space realtime)
• POSIX API for real time (standard API)
• Wide architecture support
• Mainstream support by the Vanilla Kernel

This project supports the evolution of the realtime preempt patch maintained by Ingo Molnar, and Thomas Gleixner. We believe that long term stability can only be achieved when the realtime aspects are as close to the Vanilla Kernel as possible.

This is the current status of Realtime Linux using the Realtime-Preempt patches:

Available in mainline Linux
Available when Realtime-Preempt patches applied
Not yet available

1) Currently being developed
2) Since kernel 2.6.24
3) Already functional
4) Merged into the release candidate of kernel 2.6.25
5) Will possibly be scheduled for inclusion into mainline Linux 2.6.26

• The Linux Kernel: Linux Vanilla Kernel
• The Real Time Preempt Patch: RT Preempt Download Page at kernel.org

Kernel

www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.21.6.tar.bz2

RT-Preempt Patch

www.kernel.org/pub/linux/kernel/projects/rt/older/patch-2.6.21.6-rt21

A description how to equip the Linux kernel wth realtime capabilities is given here.

• Wiki
• RTAI
• Xenomai
• Montavista
• Timesys
• Wind River