There are several C programs in c_src directory. We can compile all the C programs in c_src using # cmake -S . -B build # cmake --build build Their compile output inside c_src/build directory

There are BPF C programs inside bpf directory. These are equivalent to C program from c_src.
As, you can see in bpf, we have vmlinux.h, template.c, Makefile and BPF C programs.

Makefile has all the build automation logic. It does multiple things.
(1) It does first compile BPF C to .o file
(2) Using .o generated files, it generates .skel.h (libbpf skeleton header) files inside bpf/output directory
(3) Using template.c, it first creates corresponding .skel.c files with the same name as .skel.h.
In those .skel.c files it imports .skel.h files, and substitue %s with real generated name.
For example, for HundredLoopBpf.skel.c, it replaces %s with HundredLoopBpf.
(4) Then, it compiles those all .skel.c to output files appending "Final" suffix.
For example, for HundredLoopBpf.skel.c, it compiles HundredLoopBpfFinal, which we then run inside qemu