Hi, I am new to Manjaro and this forum but I have a long history with Linux and other operating systems. For my current project I am using Manjaro Minimal and I need to have an RT kernel. The hardware platform is an RPi4. I found a lot of manjaro kernels and the mhwd-kernel tool, bit it looks like there are no RT kernels avaiable for ARM, is this correct? If not, how do I get access to an RT kernel and install it.
Up until recently I used Debian for my project and I did build my own RT kernel for that. In case no suitable kernel is available, maybe someone could point me to the correct instructions for building a kernel suitable for manjaro on the RPi4. The kernel that came with Manjaro Minimal did not have its config at /proc/config.gz, so can I find that information elsewhere?
Run sudo modprobe configs first then look for /proc/config.gz or if you have the kernel-headers package installed look at:
$ ls /usr/lib/modules/`uname -r`/build/.config
/usr/lib/modules/6.11.0-rc5-1-MANJARO-RPI5/build/.config
I have not compiled a RPi RT kernel in a long time but I used google search to get help.
Thanks 
I have cloned the kernel code from gitlab and built a package using makepkg. What is the most proper way to go from here to a system where the old kernel has been replaced with my newly built kernel (e.g. can I have pacman replace the old with the new or do I have to explicitly remove the old and install the new). Are there any rules that needs to be followed regarding the naming of my custom kernel package?
Hard to say for sure as I do not know anything about your PKGBUILD you used. In theory if you used the same kernel name as the one installed then the old kernel will be removed automatically when you install the new kernel you built. Install with sudo pacman -U your-new-kernel.zst. Otherwise the old kernel should be removed first.
Just to point out the pi4’s firmware will look for kernel8.img kernel name in /boot to use to boot in case you have it by another name.
Ok, thanks.
What does it take to make my new kernel available to the mhwd-kernel tool? Or is that not a recommended path?