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List of Open Source Real-Time Operating Systems

osrtos.com

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Re: List of Open Source Real-Time Operating Systems

#3

Love this page. After wanting to try something other than FreeRTOS, and having been frustrated with very public projects RIOT and Zephyr, I found TNEO from this page and have used it successfully in multiple gadgets. Still very happy with it.

Interesting, I am looking at Zephyr for BLE devices, so you say TNEO is a good option?

Re: List of Open Source Real-Time Operating Systems

#5

Can Linux itself be compiled/built as a realtime OS? I mean without adding additional software or hacking.

There are patchsets out there that add realtime capabilities to the kernel. But as far as I know none of them is in the mainline. I am also not confident that the kernel can be made truly hard realtime capable without major rewrites. The best bet is probably RTLinux which runs the entire Linux kernel as one of the processes managed by a hard realtime kernel.

Re: List of Open Source Real-Time Operating Systems

#6

Can Linux itself be compiled/built as a realtime OS? I mean without adding additional software or hacking.

Without any changes, you have SCHED_FIFO and SCHED_RR [1] schedulers, but despite the name, they are not really suitable for proper real-time tasks. Closest to real time on vanilla Linux is SCHED_FIFO task - as long as there is no other task with same or greater priority, your task don't yield, call syscalls or cause page fault, it won't be preempted. When it does yield (one way or the other), there are no guarantees when it's going to be rescheduled, which is severely limiting for considering it as RT.

[1] http://man7.org/linux/man-pages/man7/sched.7.html

Re: List of Open Source Real-Time Operating Systems

#7

Can Linux itself be compiled/built as a realtime OS? I mean without adding additional software or hacking.

Not at all, at it does not meet the realtime certifications for deployment into production, like for example ISO 26262.

https://en.wikipedia.org/wiki/ISO_26262

https://www.highintegritysystems.com/

Re: List of Open Source Real-Time Operating Systems

#8

Can Linux itself be compiled/built as a realtime OS? I mean without adding additional software or hacking.

Absolutely.

https://rt.wiki.kernel.org/index.php/Main_Page

This is the wiki for the PREEMPT_RT patchset. Parts of this have been moving into mainline for years, bringing the regular kernel closer and closer to real-time. However, there are some real-time features that will never be appropriate for mainline, so you can get them through this patchset. Some of the "famous" kernel devs are also very active in PREEMPT-RT; it's as official as you can get short of being in the mainline kernel.

For lots of uses, the regular kernel is already realtime enough.

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