reproduce (this is a W=1 build):
        # https://github.com/projectacrn/acrn-kernel/commit/27615544e0963192757b1bf6433830cb17b19274
        git remote add acrn https://github.com/projectacrn/acrn-kernel
        git fetch --no-tags acrn 6.12/linux
        git checkout 27615544e0963192757b1bf6433830cb17b19274
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/virt/acrn/