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Raspbian OS uses LXDE as opposed to XFCE so that could be the difference. I can say that I thought latency was better when running with a Raspbian OS on my RP-400. Or there could be other factors at play.

I built a successful non-rt kernel based on 6.1.y and now building a realtime one with 6.1.59 rt patch, patch went with no issues, so that's a good sign.

It's all fun & games so far.

I didn't try the your image rod but notice in the kernel package there was no rp5 dtb file so just assumed it would be a non starter, plus it was 1:00am and the dog was looking at me funny, like it was time for bed.

danielfmo wrote:

Kernel built with latest 6.1.y commit with rt16 patch does boot with previously shared bookwork image.
 

Perhaps change the commit to 6e5a08f736d0366e125a5b84b01d9affc86ddf58
This is when the 6.61 branch was merged into 6.1.y on Nov 3
This will at least lock in a known position rather than just following the head.

For reference we are looking at the 6.1.y commits here github.com/raspberrypi/linux/commits/rpi-6.1.y 

Ran the same commands as the OP to test latency, histogram was wierd:
 

Then I realized the "Using POSIX non-realtime" message when starting the latency test despite the PREEMPT_RT kernel. 
 

Kernel built with latest 6.1.y commit with rt16 patch does boot with previously shared bookwork image.

rodw wrote:

Cornholio post=285614 userid=35653
if you use the commit we have been using it wont boot, if my experience is anything to go by. I'm trying to build natively with the 6.1.y branch
I hope it does now. There isn't a later PREEMPT_RT merged into their kernel.
Its possible if you accepted the defaults you built a 4b kernel
You have to run menuconfig as it was configured to build a kernel for the 4b/400 with a saved defconfig

I tried that image and it does not boot in a rpi5, in fact there are no bcm2712-rpi-5-b.dtb file being generated, so I'd assume that 5_6.1.54-rt15 does not support the rpi5. 

I merged your master branch into the linuxcnc-2.9.1 and updated the kernel hash and patch to 5_6.1.59-rt16. 
Kernel gets into gets into a "running /scripts/local/block" loop and the rootfs fails to build.

chroot: failed to run command ‘/debootstrap/debootstrap’: Exec format error
make: *** [Makefile:157: rootfs] Error 126

I used the kernel-builder script referenced earlier, no boot with the commit we've used for the rp4 (non-realtime), finally got it to boot with the 6.1.y branch.

One thing of note in the commit there is no arch/arm64/configs/bcm2712_defconfig but it is there in the 6.1.y branch.

cornholio wrote:

if you use the commit we have been using it wont boot, if my experience is anything to go by. I'm trying to build natively with the 6.1.y branch

I hope it does now. There isn't a later PREEMPT_RT merged into their kernel.
Its possible if you accepted the defaults you built a 4b kernel
You have to run menuconfig as it was configured to build a kernel for the 4b/400 with a saved defconfig

I have uploaded an image for the Raspberry Pi 5 here:
drive.google.com/drive/folders/1B29ewKVL...0QJGj?usp=drive_link
The RT kernel and the headers are available in the kernel sub folder. You could try installing both with dpkg -i on an ordinary image.

Please let me know how you get on.
Note the Linuxcnc repos are set up in your sources. (I hope) 
so
sudo apt update
sudo apt upgrade 
should be valid and not break anything.
But there will be nothjing to upgrade unless one of these happens:
1. Debian releases an updated version of Bookworm
2. Debian releases som urgent security patches
3. Linuxcnc doeas an upgrade from version 2.9.1

Please give your feedback I don't have a Pi 5.

if you use the commit we have been using it wont boot, if my experience is anything to go by. I'm trying to build natively with the 6.1.y branch

Not me.... 

But....
I have synced my repo with upstream and they say the pi5 is supported now in the image builder we use.
I am building an image for the Pi5 as we speak.
The kernel built OK but I may have had an error building the root file system. Checking again.
If I have any luck, I will  share a file.
 

Sorry both you & rodw.

Hi, 

that is what I tried to point out in my previous message: forum.linuxcnc.org/9-installing-linuxcnc...pi-5?start=10#285154

Setting the board to BCM2712 does not work and the RPI5 gets into a "running /scripts/local/block" loop

As an additional note, there's this also written in the PREENPT_RT release page (github.com/kdoren/linux/releases/tag/rpi_6.1.54-rt15)

NOTE: The installation instructions in the wiki work for debian bullseye, and currently require changes for debian bookworm. Bookworm (like Ubuntu) expects the files to be copied into directory 

/boot/firmware/

 instead of 

/boot/

cornholio wrote:

Man I'm having a hell of a time getting an real time kernel to boot on my RPi5, any chance of sharing your image ?

rpi-image-builder was no good either

Are you addressing me?

Preformed a git pull and had no luck

got "running /scripts/local/block" loop

Building a non-realtime kernel natively ATM using the script above to see how we go. If that boots I'll try a building a real time kernel.

Is it the branding that prevent us from distributing a image based on the Raspbain-OS ?

Hmm, Cornelius upstream added preliminary support for the 5b in early october.

github.com/pyavitz/rpi-img-builder
the commit is at github.com/pyavitz/rpi-img-builder/commi...a0b81cf61efcf56500ea

Maybe its time to merge upstream into my repo. Then just change the board when building  and it should work

I may have time later tonight to give that a go.