reproduce (this is a W=1 build):
        git checkout next-20260120
        b4 shazam https://lore.kernel.org/r/20260121145731.3623-12-david.laight.linux@gmail.com

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # apt-get install sparse
        # sparse version: v0.6.4-73-gfbdde312

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.5.0 ~/lkp-tests/kbuild/make.cross W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=mips olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.5.0 ~/lkp-tests/kbuild/make.cross W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=mips SHELL=/bin/bash arch/mips/kernel/ arch/mips/mm/ drivers/auxdisplay/ drivers/base/regmap/ drivers/bluetooth/ drivers/bus/ drivers/clk/ drivers/clocksource/ drivers/counter/ drivers/crypto/ drivers/cxl/core/ drivers/dma/ drivers/dpll/zl3073x/ drivers/extcon/ drivers/firmware/broadcom/ drivers/firmware/qcom/ drivers/fpga/ drivers/gpio/ drivers/gpu/ipu-v3/ drivers/hwmon/ drivers/hwtracing/ptt/ drivers/input/rmi4/ drivers/input/serio/ drivers/input/touchscreen/ drivers/irqchip/ drivers/mailbox/ drivers/media/rc/ drivers/memory/ drivers/mfd/ drivers/misc/ drivers/mtd/devices/ drivers/mtd/maps/ drivers/mtd/nand/ drivers/mtd/spi-nor/ drivers/mux/ drivers/ntb/ drivers/nvmem/ drivers/opp/ drivers/pci/ drivers/perf/ drivers/phy/allwinner/ drivers/phy/rockchip/ drivers/phy/st/ drivers/pinctrl/ drivers/pmdomain/actions/ drivers/pmdomain/mediatek/ drivers/pmdomain/renesas/ drivers/pmdomain/starfive/ drivers/remoteproc/ drivers/reset/ drivers/rtc/ drivers/soc/mediatek/ drivers/soc/qcom/ drivers/soc/renesas/ drivers/spi/ drivers/thunderbolt/ drivers/virt/vboxguest/ drivers/virtio/ drivers/watchdog/ fs/debugfs/ fs/fuse/ kernel/ lib/ mm/ net/bluetooth/ net/core/ net/devlink/ net/ethtool/ net/ieee802154/ net/mac802154/ net/sched/ security/