how to compile as an external kernel module?

[erophey7]

I tried this instruction: https://www.kernel.org/doc/Documentation/kbuild/modules.txt, but it didn’t work:

erophey7@compudahter-kubuntu:~/eblya/8821au-20210708$ make -C $HOME/eblya/android_kernel_xiaomi_lahaina/out M=$PWD ARCH=arm64 CC=clang CLANG_TRIPLE=aarch64-linux-gnu- LLVM=1 LLVM_IAS=1 CROSS_COMPILE=$TC_DIR/bin/llvm-

make: Entering directory '/home/erophey7/eblya/android_kernel_xiaomi_lahaina/out'
  Building modules, stage 2.
  MODPOST 0 modules
make: Leaving directory '/home/erophey7/eblya/android_kernel_xiaomi_lahaina/out'

Clang: google clang-r450784d
kernel: https://github.com/ghostrider-reborn/android_kernel_xiaomi_lahaina