reproduce (this is a W=1 build):
        git checkout 785f0eb2f85decbe7c1ef9ae922931f0194ffc2e
        b4 shazam https://lore.kernel.org/r/20260320-exynos850-ap2apm-mailbox-v1-4-983eb3f296fc@linaro.org

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/mailbox/