reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc64-linux-gnu
        # clang-21 might not be officially released. Try a lower version if installation fails.
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d579b04a52a183db47dfcb7a44304d7747d551e1
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout d579b04a52a183db47dfcb7a44304d7747d551e1
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash arch/powerpc/kvm/ arch/powerpc/perf/ drivers/android/ drivers/dma/ drivers/gpu/drm/amd/amdkfd/ drivers/gpu/drm/panel/ drivers/gpu/drm/vc4/ drivers/iio/imu/ drivers/infiniband/core/ drivers/isdn/mISDN/ drivers/media/test-drivers/vivid/ drivers/net/ethernet/freescale/ drivers/net/ethernet/hisilicon/hns3/ drivers/net/ethernet/intel/ice/ drivers/net/ethernet/marvell/octeontx2/af/ drivers/net/ethernet/mediatek/ drivers/net/wireless/ath/ath10k/ drivers/net/wireless/ath/ath12k/ drivers/net/wireless/ath/ath5k/ drivers/net/wireless/broadcom/brcm80211/brcmfmac/ drivers/net/wireless/broadcom/brcm80211/brcmsmac/ drivers/net/wireless/intel/iwlwifi/ drivers/net/wireless/realtek/rtl8xxxu/ drivers/net/wireless/realtek/rtlwifi/rtl8821ae/ drivers/net/wireless/realtek/rtw89/ drivers/scsi/aacraid/ drivers/scsi/lpfc/ drivers/scsi/qla2xxx/ drivers/scsi/qla4xxx/ drivers/target/iscsi/ drivers/usb/core/ drivers/usb/gadget/legacy/ drivers/usb/host/ drivers/vhost/ fs/bcachefs/ fs/ceph/ fs/f2fs/ fs/proc/ fs/smb/client/ kernel/bpf/ kernel/locking/ lib/ mm/ net/can/ sound/soc/codecs/ tools/testing/selftests/vDSO/