reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        git remote add xen-tip https://git.kernel.org/pub/scm/linux/kernel/git/xen/tip.git
        git fetch xen-tip linux-next
        git checkout xen-tip/linux-next
        b4 shazam https://lore.kernel.org/r/alpine.DEB.2.22.394.2501031501420.16425@ubuntu-linux-20-04-desktop
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/xen/