PREEMPT_RT no longer needed in Ubuntu?

vedatech
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29 Apr 2024 00:54 #299284 by vedatech

PREEMPT_RT no longer needed in Ubuntu? was created by vedatech

I read somewhere that rt PREEMPT_RT kernel build was no longer needed in Ubuntu 23.10/24.04. Is this true? If so how do you access the real time features?

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PCW
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29 Apr 2024 02:02 #299286 by PCW

Replied by PCW on topic PREEMPT_RT no longer needed in Ubuntu?

It may not be not needed by Ubuntu, but its certainly needed by LinuxCNC...

The following user(s) said Thank You: lost interest

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lost interest
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29 Apr 2024 02:03 #299287 by lost interest

Replied by lost interest on topic PREEMPT_RT no longer needed in Ubuntu?

Where did you read this ?

"I read somewhere that xxxx" often comes up but rarely is there a source.

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rodw
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29 Apr 2024 05:07 #299293 by rodw

Replied by rodw on topic PREEMPT_RT no longer needed in Ubuntu?

PCW wrote:
It may not be not needed by Ubuntu, but its certainly needed by LinuxCNC...

I suspect that they use PREEMPT_DYNAMIC which is definitely not hard real time PREEMPT_RT

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vedatech
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29 Apr 2024 17:26 #299330 by vedatech

Replied by vedatech on topic PREEMPT_RT no longer needed in Ubuntu?

I'm using ubuntu 22.04.4 with the initrd.img-5.15.0-1061-realtime kernel (PREEMPT_RT)
and a Mesa 6i25 pci card.

I get very good jitter so I'll stick with that for now.
I'm running a RIP install of 2.9.0~pre and want to upgrade to 2.9.2 but don't want to loose the edits I've done in the RIP directory.
Any suggestions?

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tommylight
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29 Apr 2024 18:56 - 29 Apr 2024 23:48 #299335 by tommylight

Replied by tommylight on topic PREEMPT_RT no longer needed in Ubuntu?

Copy the configs directory to a USB stick, if there are no special components made by you in use, that is all you need.
Ubuntu does not use RT kernels anymore (no idea why), but you can safely use Debian RT kernels in Ubuntu, i know it worked for sure with 6.1 i think.
Edit:
got reminded below by PhillC about why Ubuntu has not RT kernel, they do but it is behind a paywall!

Last edit: 29 Apr 2024 23:48 by tommylight. Reason: See above.

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vedatech
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29 Apr 2024 19:32 #299338 by vedatech

Replied by vedatech on topic PREEMPT_RT no longer needed in Ubuntu?

I cloned what I though was 2.9.2 but VERSION says 2.10.0-pre0. It works but should I go back to 2.9.2 which is supposed to be stable. How do I get that version? Is there a branch name for it?

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tommylight
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29 Apr 2024 20:23 #299342 by tommylight

Replied by tommylight on topic PREEMPT_RT no longer needed in Ubuntu?

Probably should say 2.9 instead of Master somewhere.
Sorry for the vague reply but was long ago.

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phillc54
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29 Apr 2024 23:43 #299359 by phillc54

Replied by phillc54 on topic PREEMPT_RT no longer needed in Ubuntu?

ubuntu.com/real-time

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tommylight
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29 Apr 2024 23:46 #299360 by tommylight

Replied by tommylight on topic PREEMPT_RT no longer needed in Ubuntu?

Yup, but behind a paywall.

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