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VNU Net: Linux to go live with realtime interface

By John Leyden, VNU Net

An application interface that provides enhanced capabilities for
the development of realtime Linux applications has been announced
this week.

Real Time Application Interface (RTAI) version 1.3 will also
make it easier for developers to write and debug those
applications. It will be made available under the Free Software
Foundation’s LGPL open source licence.

The release extends the ability of Linux to replace proprietary
operating systems that run realtime systems, which are common in
sectors such as telecoms, medical electronics, weapons systems and
particularly industrial automation. Its use is expected to be
extended to web servers.

Martin Brampton, chief analyst at Bloor Research, said:
Providing realtime availability and reliability in Linux will
allow users to move away from the use of tricky proprietary
systems, that have to be customised.

“If users have access to an operating system like Linux, they
would have full access so that they can know what they are doing
and the development process,” he said.

According to Brampton, consistency in performance is far more
important for realtime systems than blazingly fast performance.
Realtime Linux distributions from vendors like Lynx are already in
use in applications like process automation, and the enhancement of
the realtime interface can only push Linux further into this area,
he added.

RTAI now includes dynamic memory allocation, an enhanced
interface, and Perl bindings for soft realtime task
development.

With dynamic memory allocation, realtime applications running
under RTAI are able to dynamically allocate and free memory from a
pool using the management module’s standard API. Previously,
dynamic memory allocation has not been possible in any of the
realtime Linux kernels, and calls to allocate and free memory from
realtime tasks had to be avoided. Thus realtime applications were
required to allocate memory usage before entering realtime
operation.

The interface development allows users to access information on
the state of the application and RTAI realtime service kernel
modules, including the scheduler, FIFOs (First-in, First-out),
interrupts, and memory manager.

Features that allow developers to build a realtime task under
the memory protection of Linux and dynamic switching of tasks
between the hard/soft realtime modes from within an application,
have also been added.

Enhancements have also been added to ensure that the system
recovers gracefully after the crash of a Linux task.