reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://git.kernel.org/pub/scm/linux/kernel/git/jfern/linux.git/commit/?id=e3d86dd373496072b321f826fa24e034dba7d153
        git remote add jfern https://git.kernel.org/pub/scm/linux/kernel/git/jfern/linux.git
        git fetch --no-tags jfern nova/rmcall
        git checkout e3d86dd373496072b321f826fa24e034dba7d153
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.1.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=microblaze olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.1.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=microblaze SHELL=/bin/bash