[SOLVED] Real time kernel packaging

Halano · 2024-11-19 11:00:06

Should I use the rt package of the kernel or use the default version of 6.12 when it's dropped into the Core
because PREEMPT_RT support merged For Linux 6.12 and all it takes a build flag to enable it
without the need of arch patching the kernel would that flag make the package separate into linux-rt

I need explanation would real time be enabled by default on 6.12.x or that requires the separate package ?

Last edited by Halano (2024-11-19 12:09:28)

Forum_Liker · 2024-11-19 11:50:39

The real-time capabilities of the Linux kernel are not enabled by default, even in the latest versions of the kernel. Real-time functionality in Linux is typically provided through the use of the Real-Time Preemption Patch (also known as the "PREEMPT_RT" patch) or the PREEMPT_RT-based real-time Linux distributions.

In the case of the Linux kernel version 6.12.x, the real-time functionality would not be enabled by default. To use the real-time capabilities, you would need to either:

1. Apply the PREEMPT_RT patch to the standard Linux kernel 6.12.x source code and compile the kernel with the necessary configurations.

2. Use a real-time Linux distribution, such as:

Xenomai
RTAI (Real-Time Application Interface)
Linux-RT
Preempt-RT Linux
These distributions come with the PREEMPT_RT patch already applied and configured, providing a fully real-time-enabled Linux environment.

It's important to note that the real-time functionality in Linux is a complex topic and requires careful configuration and optimization to ensure proper real-time behavior. The specific steps to enable real-time on Linux kernel 6.12.x may vary depending on the distribution and the use case.

Halano · 2024-11-19 12:08:35

Forum_Liker wrote:

The real-time capabilities of the Linux kernel are not enabled by default, even in the latest versions of the kernel. Real-time functionality in Linux is typically provided through the use of the Real-Time Preemption Patch (also known as the "PREEMPT_RT" patch) or the PREEMPT_RT-based real-time Linux distributions.
In the case of the Linux kernel version 6.12.x, the real-time functionality would not be enabled by default. To use the real-time capabilities.

My thanks for explaining right on topic this all I wanted to read for my better understanding around real time kernels..

mithrial · 2024-11-19 12:20:45

Is this information correct? From the 6.12 change log, it reads that this patch is now included.
However, I lack the information how it is actually activated. There is a "preempt" Kernel Parameter but I don't know if this the correct on.

gromit · 2024-11-19 12:34:33

Well with 6.12 the realtime stuff is all included upstream but it's not only a runtime switch, there need to be config options set etc in order to make the kernel also behave like a realtime one

Scimmia · 2024-11-19 12:59:01

No, Forum_Liker is not correct. The patches have been merged, all that's needed now is the correct config.

But that's all that changes. Instead of patching, it's just config. Nothing else. It's still requires a separate build, and a separate package, and it's something very, very few people actually want with desktop linux anyway.

Forum_Liker · 2024-11-19 13:02:37

Scimmia wrote:

just config

need an example

gromit · 2024-11-19 13:13:38

An example wont help with that, the Linux kernel now contains a version of the RT patchset and it is usable if you set the relevant config switches (like CONFIG_PREEMPT_RT).

https://www.heise.de/en/news/After-20-y … 35651.html

Halano · 2024-11-19 17:00:15

I think mithrial maybe correct

mithrial wrote:

Is this information correct? From the 6.12 change log, it reads that this patch is now included.
However, I lack the information how it is actually activated. There is a "preempt" Kernel Parameter but I don't know if this the correct on.

As Scimmia said

Scimmia wrote:

The patches have been merged, all that's needed now is the correct config.

All the user had to do to enable real time by adding kernel parameters in grub unless these patch disabled by arch build configs.

Last edited by Halano (2024-11-19 17:05:24)

V1del · 2024-11-19 17:08:40

Forum_Liker's response is a ShitGPT generated generic blurp, I'd not put much emphasis or belief into that. I'd also assume the situation will be like scimmia foresees, there are still two packages just without the need to carry an out of tree patch. I doubt that this is trivially runtime switchable, at least not initially.

Scimmia · 2024-11-19 17:32:36

CONFIG_PREEMPT_DYNAMIC (which allows the preempt parameter) only works with none, voluntary, and full. It doesn't work with rt, which requires much deeper changes and can only be done at build time at this point.

Halano · 2024-11-19 17:32:59

V1del wrote:

Forum_Liker's response is a ShitGPT generated generic blurp, I'd not put much emphasis or belief into that. I'd also assume the situation will be like scimmia foresees, there are still two packages just without the need to carry an out of tree patch. I doubt that this is trivially runtime switchable, at least not initially.

hehe Forum_Liker just wanted to help >_>
so much misinformation right here however, thanks for approval V1del information's it seems more transparent now.

archdub · 2024-11-21 00:23:47

quote:

"On September 19, Thomas Gleixner delivered the pull request for the realtime preemption enablement patches to Linus Torvalds — in printed form, wrapped in gold, with a ribbon, as Torvalds had requested. It was a significant milestone, marking the completion of a project that required 20 years of effort. Congratulations are due to everybody involved.

Torvalds acted on the pull request the following morning."

https://lwn.net/Articles/990985/

Mapleleaf · 2025-01-03 17:53:24

(I posted a new topic instead of my previous post here: https://bbs.archlinux.org/viewtopic.php … #p2218060)

Edit: I put back my question in full here for clarity, as it has been answered in the present topic:

is there some ETA for a 6.12-RT?

The compile option PREEMPT_RT is not enabled in the standard 6.12 kernel, only PREEMP_DYNAMIC, and that changes a lot the latency, which leads to problems especially when recording audio with audio interfaces etc.
To get PREEMPT_RT at compile time, we need to enable "Fully Preemptible Kernel (Real-Time)" in the "Preemption Model" menu (of "General Setup", in make menuconfig), but "Fully Preemptible" is not an option visible by default, for that we need to enable the "Configure standard kernel features (expert users) (NEW)" option of "General Setup".

Even if I figured out where the RT option is, I'd still be glad to have an official RT kernel, because there are many other different compile options between standard and RT kernel besides the PREEMPT stuff, and I've not yet looked into what is important and not.

Last edited by Mapleleaf (2025-01-03 18:25:15)

gromit · 2025-01-03 17:57:12

Yes, there are separate packages with the realtime patchset available: https://archlinux.org/packages/?q=linux-rt
These are not yet based on the "official" kernel, but will be in the future (atleast I guess so)!

Mapleleaf · 2025-01-03 18:01:26

Thanks a lot for your quick reply.
I messed up a little bit by moving my post to a new topic before I saw your post.

So, we should expect a linux-rt-6.12 but should just be a little more patient, am I right?

Last edited by Mapleleaf (2025-01-03 18:01:53)

gromit · 2025-01-03 18:07:40

Mapleleaf wrote:

So, we should expect a linux-rt-6.12 but should just be a little more patient, am I right?

Yes I'd expect it to land in a while!

Arch Linux

#1 2024-11-19 11:00:06

[SOLVED] Real time kernel packaging

#2 2024-11-19 11:50:39

Re: [SOLVED] Real time kernel packaging

#3 2024-11-19 12:08:35

Re: [SOLVED] Real time kernel packaging

#4 2024-11-19 12:20:45

Re: [SOLVED] Real time kernel packaging

#5 2024-11-19 12:34:33

Re: [SOLVED] Real time kernel packaging

#6 2024-11-19 12:59:01

Re: [SOLVED] Real time kernel packaging

#7 2024-11-19 13:02:37

Re: [SOLVED] Real time kernel packaging

#8 2024-11-19 13:13:38

Re: [SOLVED] Real time kernel packaging

#9 2024-11-19 17:00:15

Re: [SOLVED] Real time kernel packaging

#10 2024-11-19 17:08:40

Re: [SOLVED] Real time kernel packaging

#11 2024-11-19 17:32:36

Re: [SOLVED] Real time kernel packaging

#12 2024-11-19 17:32:59

Re: [SOLVED] Real time kernel packaging

#13 2024-11-21 00:23:47

Re: [SOLVED] Real time kernel packaging

#14 2025-01-03 17:53:24

Re: [SOLVED] Real time kernel packaging

#15 2025-01-03 17:57:12

Re: [SOLVED] Real time kernel packaging

#16 2025-01-03 18:01:26

Re: [SOLVED] Real time kernel packaging

#17 2025-01-03 18:07:40

Re: [SOLVED] Real time kernel packaging

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