scx_lib: use the proper bpftool

[arighi]

Make sure to use the right bpftool when building scx_lib, instead of always relying on the system's bpftool.

Fixes: 3d72a8e ("add library infrastructure and turn allocator into a library")

[likewhatevs]

btw #1067 (being merged atm) fixes this also

[arighi]

btw #1067 (being merged atm) fixes this also

Hm.. nope, it's still broken:

FAILED: lib/lib.bpf.o
/home/nvidia/arighi/src/scx/meson-scripts/compile_scx_lib /home/nvidia/arighi/src/scx/build/bpftool/src/bpftool lib/lib.bpf.o lib lib/sdt_task.bpf.o
/home/nvidia/arighi/src/scx/meson-scripts/compile_scx_lib: line 12: /home/nvidia/arighi/src/scx/build/bpftool/src/bpftool: No such file or directory

I think bash doesn't like the double quotes around "$bpftool".

[arighi]

Updated on top of #1067, @likewhatevs can you check if this works for you as well?

[arighi]

@likewhatevs actually scratch that, it's still not working, something else is broken now... looking.

Now I need to run meson compile -C build scx_simple twice, the first time it doesn't build because it doesn't find bpftool... wth?

[likewhatevs]

this worked for me without needing to run compile twice?:

rm -rf build
meson setup build
meson compile -C build scx_simple

[arighi]

@likewhatevs I see the problem, scx_lib should depend on bpftool_target. It seems to be fixed now.

[likewhatevs]

I tested the latest commit on my system and it worked also (but it worked before for me so maybe there's something non-standard on my system making this always work).

[arighi]

I tested the latest commit on my system and it worked also (but it worked before for me so maybe there's something non-standard on my system making this always work).

It could be also a timing / parallelization issue and in your case it was always building bpftool before any scheduler (or you are using the system's bpftool).