Libbpf is used at several locations in the repository. Most of the time, the tools relying on it build the library in its own directory, and include the headers from there. This works, but this is not the cleanest approach. It generates objects outside of the directory of the tool which is being built, and it also increases the risk that developers include a header file internal to libbpf, which is not supposed to be exposed to user applications. This set adjusts all involved Makefiles to make sure that libbpf is built locally (with respect to the tool's directory or provided build directory), and by ensuring that "make install_headers" is run from libbpf's Makefile to export user headers properly. This comes at a cost: given that the libbpf was so far mostly compiled in its own directory by the different components using it, compiling it once would be enough for all those components. With the new approach, each component compiles its own version. To mitigate this cost, efforts were made to reuse the compiled library when possible: - Make the bpftool version in samples/bpf reuse the library previously compiled for the selftests. - Make the bpftool version in BPF selftests reuse the library previously compiled for the selftests. - Similarly, make resolve_btfids in BPF selftests reuse the same compiled library. - Similarly, make runqslower in BPF selftests reuse the same compiled library; and make it rely on the bpftool version also compiled from the selftests (instead of compiling its own version). - runqslower, when compiled independently, needs its own version of bpftool: make them share the same compiled libbpf. As a result: - Compiling the samples/bpf should compile libbpf just once. - Compiling the BPF selftests should compile libbpf just once. - Compiling the kernel (with BTF support) should now lead to compiling libbpf twice: one for resolve_btfids, one for kernel/bpf/preload. - Compiling runqslower individually should compile libbpf just once. Same thing for bpftool, resolve_btfids, and kernel/bpf/preload/iterators. (Not accounting for the boostrap version of libbpf required by bpftool, which was already placed under a dedicated .../boostrap/libbpf/ directory, and for which the count remains unchanged.) A few commits in the series also contain drive-by clean-up changes for bpftool includes, samples/bpf/.gitignore, or test_bpftool_build.sh. Please refer to individual commit logs for details. Quentin Monnet (9): tools: bpftool: remove unused includes to <bpf/bpf_gen_internal.h> tools: bpftool: install libbpf headers instead of including the dir tools: resolve_btfids: install libbpf headers when building tools: runqslower: install libbpf headers when building bpf: preload: install libbpf headers when building bpf: iterators: install libbpf headers when building samples/bpf: install libbpf headers when building samples/bpf: update .gitignore selftests/bpf: better clean up for runqslower in test_bpftool_build.sh kernel/bpf/preload/Makefile | 19 +++++++--- kernel/bpf/preload/iterators/Makefile | 18 ++++++---- samples/bpf/.gitignore | 3 ++ samples/bpf/Makefile | 36 +++++++++++++------ tools/bpf/bpftool/Makefile | 27 ++++++++------ tools/bpf/bpftool/gen.c | 1 - tools/bpf/bpftool/prog.c | 1 - tools/bpf/resolve_btfids/Makefile | 17 ++++++--- tools/bpf/resolve_btfids/main.c | 4 +-- tools/bpf/runqslower/Makefile | 12 ++++--- tools/testing/selftests/bpf/Makefile | 22 ++++++++---- .../selftests/bpf/test_bpftool_build.sh | 4 +++ 12 files changed, 110 insertions(+), 54 deletions(-) -- 2.30.2
