Failed to serialize the AOSP build. It always tries to run many soong_build processes in parallel

Trying to debug build problem Faild to build Android 11 AOSP for Rock PI 4AB

The first step is to serialize the build, so I can get the actual build error. But even that is difficult.

I tried the following:
make -j1
m -j1

export SOONG_JOBS = 1
export NINJA_ARGS = “-j1”
modified build/soong/ui/build/config,go, changed the line “ret.parallel = runtime.NumCPU() + 2” to " = 1"

All the above failed to disable the parallelism. There still still lots of soong_build processes running in parallel.

What is the right way to serialize the build?