On Mon, 2024-06-10 at 22:14 +0100, Richard Copley wrote:
> What is the correct way to cause jobserver information to be passed
> to
> child processes? I tried this Makefile:
>
> all:
> @echo Jobserver present? $(filter jobserver,$(.FEATURES))
> +@sh -c "echo \"make toplevel MAKEFLAGS=${MAKEFLAGS}\""
> +@sh -c "echo \"child toplevel MAKEFLAGS=$${MAKEFLAGS}\""
> +$(MAKE) recursive
>
> recursive:
> +@sh -c "echo \"make recursive MAKEFLAGS=${MAKEFLAGS}\""
> +@sh -c "echo \"child recursive MAKEFLAGS=$${MAKEFLAGS}\""
>
> # Makefile ends
>
> The actual output is:
>
> make -j
This is your problem.
When you run "make -j" with no limit, then make doesn't ever create a
jobserver. Why create a jobserver when you have an unlimited number of
jobs to run?
In this case the "-j" flag just tells make to run everything it
possibly can with no limits.
If you provide a limit you'll see different behavior, e.g.:
make -j5
