Real-time Armbian, now that it is part of kernel 6.12?

[grixm]

Linux 6.12 mainlined PREEMPT_RT, real-time preemption. As far as I understand, one no longer needs to muck about with patches, the kernel can simply be compiled for real-time use with normal compiler flags on any common architecture.

This makes Linux suitable for tasks with precise latency requirements, of which there is a lot of in the embedded space.

 

Has anyone tried this on Armbian 25.2 now that it uses the 6.12 kernel? Does it work? How would one compile Armbian with it?

[Igor]

On 3/25/2025 at 2:15 PM, grixm said:

As far as I understand, one no longer needs to muck about with patches, the kernel can simply be compiled for real-time use with normal compiler flags on any common architecture.

 

Correct, but I also haven't tried it yet.

 

On 3/25/2025 at 2:15 PM, grixm said:

How would one compile Armbian with it?

 

https://docs.armbian.com/Developer-Guide_Build-Preparation/

Once you get it running, choose this:

 

 

and enable what needs to be enabled (there must be guides around the internet and AI also usually knows). Make sure to freeze this custom kernel, so update won't be replacing it later.

[grixm]

Thanks!
Indeed I was able to compile it with a custom kernel, the preemption method option was in the system settings in the menu, and for good measure I also changed the system time slice resolution from 250Hz to 1000Hz in the power settings.

It boots and seems stable so far, but I need to test more. 

 

And yes, also thanks for the tip regarding freezing the updates. Because after an "apt upgrade" it was indeed overwritten by a non-RT kernel.
However I have one question regarding this, @Igor. How can I build Armbian for the latest possible version, since I'm not able to update it after building? When building, I checkout out branch v25.02, but it resulted in building 25.2.1, not 25.2.3 which is the latest. Small difference but still...

Edited Friday at 03:58 PM by grixm

[Igor]

5 hours ago, grixm said:

How can I build Armbian for the latest possible version

Always use main branch, older branches are here for reference and to build with sources at the state of initial build. We had several bug fix builds after point release, but they were made from main branch ... as we don't backport commits to frozen branch. Not enough people ...

 

OS version is not determined by build framework, but externally. https://github.com/armbian/os/blob/main/stable.json Which version is bumped when any new Armbian package is sent to the repository. You can also set version with a parameter IMAGE_VERSION=25.2.3 ...

In theory, if we would have "endless" computing / storage resources, we could make RT kernels for all variants. Currently, this is a bit insane  as there are too many kernels. 

[grixm]

Ooh okay, I see now. Thanks again!