Xenomai is officially supported by NXP in Industrial IoT Solution Customer Release.The dual kernel core is codenamed Cobalt, the native Linux implementation is called Mercury.Both Mercury and Cobalt are supported. For details, please refer to "Chapter 9 Xenomai". You need to get the OpenIL source code to build the platform related images, the release tarballs are available at "https://github.com/openil/openil", for details please refer to "Chapter 3 Getting started" section in https://www.nxp.com.cn/docs/en/user-guide/OpenILUG-1.11.pdf.
Please try whether you could use the following method to build your own Xenomai application in OpenIL.
Please go to Xenomai build folder openil/output/build/xenomai-2.6.4, please refer to the test program clocktest in src/testsuite/clocktest/ as an example.
After add your app code in Xenomai source code folder, please run make xenomai-reconfigure, followed by make or make xenomai, it will restart the configuration, compilation and installation of the package.
For details please refer to "8.3. Understanding how to rebuild packages" in https://buildroot.org/downloads/manual/manual.html#getting-buildroot.