OP-TEE kernel headers for BCC

[BoreaWolf]

Hi all,
I am trying to use the python bcc library on OP-TEE 4.2.0 deployed on a Xilinx ZynqMP ZCU102 platorm.
The library is installed correctly, but at runtime I get the following error:

modprobe: can't change directory to '/lib/modules': No such file or directory
Unable to find kernel headers. try rebuilding kernel with CONFIG_IKHEADERS=m (module) or installing the kernel development package for your running kernel version.

I added the suggested CONFIG_IKHEADERS flag in the kconfig file and rebuilt the image but the '/lib/modules' directory still does not appear.
I also tried adding the CONFIG_HEADERS_INSTALL flag, but the result is the same.
Both flags are active as showed by checking the configuration at runtime:

# cat /proc/config.gz | gunzip | grep -i headers
CONFIG_IKHEADERS=m
CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS=y
CONFIG_HEADERS_INSTALL=y

Can anyone help me to understand how the kernel headers file can be added in the compiled image, if possible?
Thank you very much for the help.

[jforissier]

Hi @BoreaWolf, what is your build environment? Your build command?

[BoreaWolf]

Hi @jforissier and thanks for looking into this.
I am cross-compiling op-tee from a Ubuntu 22.04 machine.
I followed the main instructions provided in the zynqmp wiki page.
To be specific, these are the commands that I used:

mkdir <optee_dir>
cd <optee_dir>
repo init -u https://github.com/OP-TEE/manifest.git -m zynqmp.xml
repo sync
cd build
make -j$(nproc) toolchains
make -j$(nproc) PLATFORM=zynqmp-zcu102 image

I downloaded the 2023.1 firmware from the soc-prebuilt-firmware github and updated the makefiles to refer to the new version.
I also made a test with the 2021.1 firmware without modifying any of the makefiles, but the result is the same.
To ensure that the changes made to the build/kconfigs/zynqmp.conf file were applied, before compiling the image I also recreate the linux-xlnx/.config file via make linux-defconfig-clean linux-defconfig.

[jforissier]

There is a platform that supports building and installing kernel modules, it's Rockpi4. See LINUX_MODULES=y in rockpi4.mk and OP-TEE/build@366accb7. Perhaps you need something similar.