reproduce (this is a W=1 build):
        git remote add rppt-memblock https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock.git
        git fetch rppt-memblock for-next
        git checkout rppt-memblock/for-next
        b4 shazam https://lore.kernel.org/r/20260403194526.477775-3-hannes@cmpxchg.org
        # apt-get install llvm-dev

        # save the config file
        make W=1 ARCH=i386 olddefconfig
        make W=1 ARCH=i386 
        make W=1 headers_install
        make W=1 -C tools/testing/selftests