Sorry Song, I did not state clear. libbpf_ensure_mem() is declared in libbpf_internal.h, we want to use libbpf_ensure_mem() in trace_helpers.c, Unforturnately, we could only include the headers 'install_headers:' defined in tools/lib/bpf/Makefile, the 'install_headers:' target does not include libbpf_internal.h, like: tools/testing/selftests/bpf/trace_helpers.c:17:10: fatal error: libbpf_internal.h: No such file or directory 17 | #include "libbpf_internal.h" | ^~~~~~~~~~~~~~~~~~~ tools/testing/selftests/bpf/trace_helpers.c:17:10: fatal error: bpf/libbpf_internal.h: No such file or directory 17 | #include "bpf/libbpf_internal.h" | ^~~~~~~~~~~~~~~~~~~~~~~ How about 1. dup-declare libbpf_ensure_mem() in trace_helpers.c 2. move libbpf_ensure_mem() declare into libbpf_common.h Which one do you like best. Best wishes, Rong Tao