Minimal custom rootfs - considerations and starting point for begginers

[BSP_User]

I saw many posts regarding this subject but I didn’t find answers for my basic, beginner’s questions.
Hope getting some help from the more experienced users here.

I have an Orin Nano devkit hosting an Orin NX SoM with JP 5.1.1
My general goal is to improve boot time and my current goal , for learning purposes, is to create a custom minimal rootfs for my system.

1. Which one you recommend for building custom minimal rootFS - Buildroot or Yocto and why?

2. I don’t understand why RootFS is “specific” to a platform. From my understanding I get all the statically built in drivers with my kernel and the rest as kernel module. So by this logic, I need to download the suitable kernel with its built in drivers and kernels modules matching to my hardware and integrate it with my Rootfs. Which part of the Rootfs is tied specifically to specific platfrom?

3. For a quick solution I can download the Buildroot project , build minimal custom rootfs with the toolchain sources supplied by Nvidia and that’s it - I have a new minimal rootFS.
   What I need to do now? what are the steps I have to do in order to “connect” my new rootfs to my system?

4. Is there anything that just wont work with Nvidia JP if I use a custom minimal rootfs and not the supplied sample rootfs? some app or some incompatibility ?

Thanks a lot for the pateince.

[DaneLLL]

Hi,
We have the guidance in
Root File System — Jetson Linux Developer Guide documentation

Please take a look and give it a try. For Yocto, you may consult with:
Yocto Support for NVIDIA Jetson Platforms - Yocto Support for NVIDIA Jetson Platforms - Setting up Yocto - RidgeRun Developer Connection

For Buildroot, would need other users to share experience.

[BSP_User]

Thank you for your answer. I didn’t find answers to my questions in the section you referred me to (already read it).
I’m interested in learning how to build custom minimal rootfs by my own “from scratch” and not using the minimal sample supplied by Nvidia, Unless you say it result with the same outcome.