(updated July 5, 2000) Lineo has released AtomicRTAI, a working real-time Linux distribution that fits on a single floppy diskette. AtomicRTAI builds upon an earlier single floppy real-time distribution previously released by Zentropix in May, 1999. AtomicRTAI includes the latest version of RTAI with auto-clock detection, combined with performance measurement tools and several programs that demonstrate… hard real-time Linux operation.

An included measurement tool can be used to evaluate the key RTOS parameters of context switch time — the time taken for the CPU to stop running one task and to start running another, and jitter — the timing variance between individual scheduling points of a periodic task. This allows developers to easily evaluate the performance of RealTime Linux on their own platform without the need to extrapolate figures of merit from existing tests.

AtomicRTAI also includes LXRT, a feature which allows easy deployment of hard real-time tasks without strict kernel dependencies (see reference, below). Hard real-time tasks can thereby be developed on a desktop PC, using the standard Linux kernel, and then deployed under AtomicRTAI.

The modular architecture of RTAI allows inclusion of only those features and services that the target application requires. Thus, as little as 65 Kb of code space (on top of standard Linux) can be used to deploy a basic real-time application that only makes use of the periodic scheduler. Additional services and features can be modularly added, resulting in incremental corresponding increases in disk and memory requirements.

The full RTAI feature set now includes:

• POSIX 1003.1c API support — including pthreads, condition variables and mutexes with priority inheritance support
  
• RTOS IPCs, including — semaphores, FIFOs, mailboxes, mutexes, RPCs, shared memory
  
• PERL Bindings — for creation of soft real-time tasks from PERL scripts
  
• True SMP Support
  
• The Real-Time Linux Common API — allows the developer to use a single API for either RTLinux or RTAI code development
  
• Dynamic Memory Allocation — allows creation of one real-time task by another
  
• /proc interface — provides critical information on the real-time tasks, modules, services and processes
  
• LXRT — allows use of the RTAI system calls from within standard user space for greatly eased code development and deployment

Downloading and installing AtomicRTAI

According to Lineo, downloading and installing AtomicRTAI is simple:

• Download AtomicRTAI here
  
• Choose the disk image suitable for your computer's architecture
  
• On your Linux machine:
  • Log in as root
    
  • Put a floppy disk in the drive
    
  • Perform the following (using the name of the image file that you just downloaded):
    dd if=NAME_OF_IMAGE_FILE.img of=/dev/fd0 bs=1k
• Don't have a Linux machine? No problem.
  • From a DOS/Windows machine you can use rawrite, which you can download from here.
    
  • Run rawrite and follow the prompts.

AtomicRTAI is open source and freely distributed under the GPL and LGPL licenses. You can obtain the file system structure, the source code for the AtomicRTAI diagnostic tool, and any modules used by AtomicRTAI using anonymous CVS. CVS log-in details are available here.

 
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