Can the OPI5 be Configured to Run LCNC?

The missing firmware is something you could ignore. That firmware is only needed at the moment you'll use hardware that needs that firmware.

So I am not sure if the RT was a success or not after getting the Ubuntu Jammy image up and running. 
I flashed the image with the flag enabled for the wireless driver, I was able to boot up though for some reason the initial user I had setup on startup did setup properly. None of the folders were generated for my home directory, and I had a myriad of permissions issues like not being able do download anything from a web browser. I was able to bypass all that by creating a new user and deleting the old one. 

anyrate downloaded the wayland driver, installed the linuxcnc-uspace deb package 
however I am not seeing the low latency numbers that were observed in royka's tests, least to my understanding I am not.  I've attached a screen shot of the latency test while running youtube in the background. I ran cat /proc/version and didn't see anything that eluded to the fact it was a real time kernel. So I am starting to believe that the patch and config files didn't work. 

Honestly I am starting to feel a little wary of Armbian. seems like a lot of hoops have to be jumped through to get it to work. The correct dtb file being absent on a fresh build, the user profile being bad on the first startup. I don't think I had this many issues when I did an raw Arch install on my laptop. 

Anyrate downloading the Debian image royka provided. I'll give that a crack. But I am starting to not be as optimistic with this distro.
 

Hi,
most probably you lose th RT patch, it happens also to me simply with APT UPGRADE.. but I patched again with deb files generated.
Now I have a image well done, latency OK, vnc working, all ok except wifi, this no way.. but for the rest it's ok.
I have a USB AC1200 and a Cisco USB and I tried to configure in menuconfig most of board present but some of them doesn't allow to build,
what I have enabled doesn't make the USB adapter working..
Now I have 2-3 days out, next week I will try again.
It's really enough to enable the driver in the menu config or there is a kind of service that should be enable as well?

@kanuboy13b Like Guglielmi said possibly you've upgraded the kernel. To prevent this from happening:
sudo apt-mark hold linux-image-legacy-rockchip-rk3588

The hoops with Armbian is because we're using an unsupported kernel, but you're free to build your rt arch system. I've tried arch a few times, it's not for me, too much hassle to make basic things work.

@Guglielmi Do you mean the RTL8812 like this one?
aliexpress.com/item/32664378094.html

Enabling the driver should be enough, if you've got the one with the RTL8812 chip I've one here to test.

Exactly! It's that device, I bought on Amazon but I can say identical.
Sorry if I did not inserted enough detail in the previous post but I'm not at home so I can't take a picture..
I remember enabling something like RTL88x2eu it does't build, with other drivers less similar, it build but not work..

I do actually have the 8814EU there are different versions of these, you could check which one you've with lsusb.
To build different realtek drivers together you'll need to build them as modules, otherwise they will conflict each other.

Could you try this kernel with most usb wifi drivers enabled:
mega.nz/folder/ewBmjLpZ#QYABAmeoVzq_pFDAsGEV9Q

At least the RTL8814EU does work with this kernel.
If it still doesn't work you might need to install iw: sudo apt install iw

I will try as soon as I'm back at home.
I found the device I bought:
AC 1200

Identical.
before the patch it was working with armbian.
Maybe I could compare the config file in the drivers section to understand which one should be enabled..
I will work on it!

Hehe, yeah.... Arch is umm not for many people. I only was able to get as far as I did because it was heavily documented. Traversing unknown waters with that distro without completely knowing what your doing is severely ill advised, trying to do what we're doing would probably frustrate me only more than I already am.

I kinda figured that there were going to be issues getting a RT kernel working on the OPi5, I just figured it would be more drivers and config files, not missing dtb files that are essential for the device to boot. On the topic of unsupported kernel, has there been any interested from the Armbian group in making an official RT build of Armbian? Or is there just no demand for one hence all the hoop jumping.

So I should be able to fix the by reinstalling the Linux-image and Linux-headers deb files using apt install or dpkg  correct?

Yeah I think if the arch community would have been bigger I would like it more. It has some things that works better/faster than Debian but because not many software is made for Arch you'll need to compile a lot. The aur git does help but the things I needed were not configured right and that frustrated me indeed.

The missing dtb is because the kernel is directly from Rockchip which is missing that dtb
github.com/rockchip-linux/kernel/tree/de...64/boot/dts/rockchip

Armbian use their own fork which has the opi5 dtb in it. I could make a patch of course, there are some more things I would like to patch like the hdmi drivers which might make it possible to use panfork.

I didn't ask at the Armbian forum but saw that rodw had asked a few questions about it for another board and they weren't enthusiastic. There would need to be someone who wants to maintain it. It might not take long before the mainline kernel does work well enough, when that's ready it should be as simple as placing the preempt rt patch(es) in the right folder.

Actually, one of the developers took me under his wing and we moved off forum. Nobody knows about PREEMPT_RT and he is their real time guy who has specialized in Xenomai 4 and has not looked at PREEMPT_RT for a long time.
The build system has a lot of issues with their recent migration to their new build system, I went on holidays to Bali and we decided do give it a break for a while so he could get some of his work into mainline before resuming. I have some more pressing projects to complete right now.

The user build system is very powerful, and pretty well documented. If you are building a kernel now, you should be able to apply all your kernel config and patches in the userpatches folder for your architecture and kernel version. That is not created until you do an initial build. Use a custom config file to lock in your build parameters. I would try to use their EDGE branches and build Debian Bookworm because linuxcnc-uspace is in the Bookworm repos.

You don't need to build an image with a graphical environment as you can install that on the device from the repos. It adds a lot of time in the build system. Likewise once you can boot into Armbian (even non-rt will do), you can just build the kernel debs and copy them over and install with dpkg -i
You can check latency with cyclictest from the command line (sudo apt install rt-tests) and only install xfce and linuxcnc once you can see a reasonable result.

Hope that helps...