Re: All RTOS (linux Based ) Other than RT-Linux

Matt Giwer wrote:

Hi all, I want to know, there are any REAL TIME OPERATING
systems( RTOS) which should have total linux compatible other than RT-
Linux.

And are there any free Real time Operating systems ( Linux Based ) is
available on the Internet.

Please provide some information regarding this issue.


I have read that the kernel is interrupt driven rather than schedule driven. If that is what you mean, all linuxes are real time.

Real time systems typically guarantee some timing (interrupt latency...), so that processes can react on events in a timely manner. Furthermore the response on events has time constraints, i.e. a process must lower its priority, after doing the time critical event handling. This requires that *all* system processes behave accordingly, what's not normally the case in an preemptive multitasking system. A related requirement are memory-resident event handlers, separated somehow from the less critical swappable parts of an process.

IMO these requirements cannot be satisfied with the public Linux code, and also cannot be introduced by simple patches to the kernel etc. sources.

Some approaches make the Linux kernel simply an process, running under control of an new RT kernel. But then RT processes will have to communicate and cooperate with the RT kernel, so that they run more in parallel to the Linux kernel, instead of controlled by the Linux kernel. IMO it then is inevitable to split RT applications into an RT process, running under control of the RT kernel, and an non-RT process, running under control of the Linux kernel. One also might see the RT part as kind of a device or driver, interacting with the remaining part of the application.

IMO it will be simpler to use some available RT system, and make it's ABI so Linux-compatible, that Linux applications can be installed into such a system. But then it might be easier to install a veritable Linux into a VM, hosted by the RT OS. See also: The Xen Project.

DoDi
.

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