Cant find Fully Preemptible Kernel (RT) as an option in menuconfig

Autonomous Machines Jetson & Embedded Systems Jetson Orin NX
1

Hello, I am trying to work with Franka arm which requires the kernel OS be Fully Preemptible Kernel. I am working with Stereolab Zed Box Orin.
Here’s the specification of the board

JetPack: 5.1 (L4T R35.3.1)
Kernel: 5.10.104-tegra
OS: Ubuntu 20.04 LTS (Focal Fossa)

Here’s what I have tried

  1. I have downloaded the source JetPack at here
  2. then I did " sudo tar -xjf public_sources.tbz2 -C /usr/src/ " to untar to usr/src
  3. I then download the PREEMPT_RT Patches from here and untar as well then apply the patch
  4. I did that inside this directory /usr/src/Linux_for_Tegra/source/public/kernel/kernel-5.10

when I run menuconfig I don’t see the option of Fully Preemptible Kernel (RT)
I can see

No Forced Preemption (Server)
Voluntary Kernel Preemption (Desktop)
Preemptible Kernel (Low-Latency Desktop)
3

Hi,
For building RT kernel, please follow the steps:

Kernel Customization — NVIDIA Jetson Linux Developer Guide 1 documentation

Would suggest validate it on Orin NX developer kit(Orin NX module + Orin Nano carrier board) and then on your custom board.

4

I followed the steps with the difference in step 5
I don’t have this directory
Linux_for_Tegra/rootfs/usr/lib/modules/$(uname -r)/kernel/drivers/gpu/nvgpu/nvgpu.ko

I have /boot directory which contains the Image and dbt, I replaced the Image after making a backup of the old, but it’s not working,
It keeps booting into the old image.

5

Hi,
Do you download the packages as default base of system image:

Jetson Linux 35.3.1 | NVIDIA Developer
Driver Package (BSP)
Sample Root Filesystem

You would need to have the default base and then replace certain files with your self-built ones.

6

No, I did not download that and I don’t seem to understand
The default base should be the currently loading boot image right?

On the zed board, it’s running stereolab SDK which is
ZED SDK for JetPack 5.0 (L4T 35.1)

Will that sdk not work with Jetson?

7

Last time we checked (more than 1y ago), the ZED SDK didn’t support RT kernel

8

Where and how did you check this?
Maybe something changed or I can confirm the same thing

9

We sent an email the support support@stereolabs.com. This was in September 2023.

10

Got a confirmation today as well, They still do not provide support for the Real-Time Kernel.
Thanks @Gorgo90

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12

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