Integrating Xenomai 4 on BeagleY-AI: Hard Real-Time Linux

Why Xenomai?

While Preempt-RT provides soft real-time capabilities, Xenomai 4 delivers hard real-time performance via its EVL (Evolvable Linux) core. This dual-kernel approach achieves:

Sub-10μs latency for time-critical tasks
Deterministic interrupt handling
Coexistence of real-time and Linux applications

Prerequisites

BeagleY-AI running Debian 12.11 2025-05-21 XFCE
Host Machine: Ubuntu 22.04+ (64-bit) with ARM cross-compiler

Step 1: Obtain Kernel Sources

(On Host Machine)

1.1 Clone Beagleboard’s Linux Kernel

git clone https://github.com/beagleboard/linux -b 6.6.58-ti-rt-arm64-r27
cd linux

1.2 Fetch Xenomai EVL Patches

git remote add xenomai https://source.denx.de/Xenomai/xenomai4/linux-evl.git
git fetch xenomai v6.6.y-evl-rebase

Step 2: Merge EVL into TI Kernel

2.1 Create a Merge Branch

git checkout -b ti-xenomai-merge
git merge xenomai/v6.6.y-evl-rebase

2.2 Resolve Merge Conflicts

Focus on:

arch/arm64: TI-specific changes vs. Xenomai’s EVL modifications.
drivers/: SPI, PWM, or Ethernet drivers.
kernel/sched: Scheduler conflicts between RT and EVL.

Step 3: Configure the Kernel

3.1 Start with BeagleY’s Default Config

make distclean
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bb.org_defconfig

3.2 Enable Xenomai EVL

make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- menuconfig

Key Options:

-> Kernel Features
    -> [*] EVL real-time core
        [*]   Enable quota-based scheduling
        [*]   Enable temporal partitioning policy
        (4)     Number of partitions
        [*]   Collect runtime statistics

Step 4: Build the Kernel

4.1 Compile Kernel & Modules

make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- LOCALVERSION="-xenomai" -j$(nproc)
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- INSTALL_MOD_PATH=./modules modules_install

4.2 Package Artifacts

tar -czf xenomai-kernel-6.6.69-xenomai.tar.gz arch/arm64/boot/Image modules/lib/modules/6.6.69-xenomai

Step 5: Deploy EVL Kernel

(On BeagleY-AI)

Copy Image to /BOOT/.
Extract modules to /lib/modules.
Update /boot/firmware/extlinux/extlinux.conf:

label microSD (default)
    kernel /Image
    append console=ttyS2,115200n8 root=/dev/mmcblk1p3 ro rootfstype=ext4 resume=/dev/mmcblk1p2 rootwait net.ifnames=0 quiet
    fdtdir /
    fdt /ti/k3-am67a-beagley-ai.dtb
    fdtoverlays /overlays/k3-am67a-beagley-ai-csi0-tevs-rpi22.dtbo
    initrd /initrd.img

Verify the kernel version:

$ uname -r
6.6.69-xenomai

Step 6: Build & Install Xenomai Libraries

(Native on BeagleY-AI)

6.1 Clone Source

mkdir ~/xenomai && cd ~/xenomai
git clone https://source.denx.de/Xenomai/xenomai4/libevl.git
git clone https://source.denx.de/Xenomai/xenomai4/linux-evl.git --depth=1 --branch v6.6.y-evl-rebase

6.2 Build libevl

mkdir build && cd build
meson setup -Dbuildtype=release -Dprefix=/usr -Duapi=~/xenomai/linux-evl ../libevl
meson compile
sudo ninja install

6.3 Validate with EVL test

sudo evl test

Expected Output:
basic-xbuf: OK, clock-timer-periodic: OK, clone-fork-exec: OK, etc.

Conclusion

Setting up Xenomai 4 on the BeagleY-AI provides a solid foundation for ultra-low latency audio and robotics applications. By merging the TI vendor kernel with the EVL core, we get the best of both worlds: full hardware support and hard real-time guarantees.