reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git/commit/?id=deb6b330c36cc9636b7381cc97a8517845ed530f
        git remote add vireshk https://git.kernel.org/pub/scm/linux/kernel/git/vireshk/linux.git
        git fetch --no-tags vireshk virtio/msg-xen
        git checkout deb6b330c36cc9636b7381cc97a8517845ed530f

        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=$HOME/0day COMPILER=gcc-15.1.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.1.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc64 SHELL=/bin/bash drivers/virtio/