Reorder includes search path to ensure $(OUTPUT) and $(CURDIR) go before
libbpf's directory. Also fix bpf_helpers.h to include bpf_helper_defs.h in
such a way as to leverage includes search path. This allows selftests to not
use libbpf's local and potentially stale bpf_helper_defs.h. It's important
because selftests/bpf's Makefile only re-generates bpf_helper_defs.h in
seltests' output directory, not the one in libbpf's directory.
Also force regeneration of bpf_helper_defs.h when libbpf.a is updated to
reduce staleness.
Fixes: fa633a0f8919 ("libbpf: Fix build on read-only filesystems")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200110051716.1591485-3-andriin@fb.com
This is a mirror of bpf-next linux tree's
tools/lib/bpf directory plus its supporting header files.
The following files will by sync'ed with bpf-next repo:
src/<->bpf-next/tools/lib/bpf/include/uapi/linux/bpf_common.h<->bpf-next/tools/include/uapi/linux/bpf_common.hinclude/uapi/linux/bpf.h<->bpf-next/tools/include/uapi/linux/bpf.hinclude/uapi/linux/btf.h<->bpf-next/tools/include/uapi/linux/btf.hinclude/uapi/linux/if_link.h<->bpf-next/tools/include/uapi/linux/if_link.hinclude/uapi/linux/if_xdp.h<->bpf-next/tools/include/uapi/linux/if_xdp.hinclude/uapi/linux/netlink.h<->bpf-next/tools/include/uapi/linux/netlink.hinclude/tools/libc_compat.h<->bpf-next/tools/include/tools/libc_compat.h
Other header files at this repo (include/linux/*.h) are reduced versions of
their counterpart files at bpf-next's tools/include/linux/*.h to make compilation
successful.
Build

libelf is an internal dependency of libbpf and thus it is required to link
against and must be installed on the system for applications to work.
pkg-config is used by default to find libelf, and the program called can be
overridden with PKG_CONFIG.
If using pkg-config at build time is not desired, it can be disabled by setting
NO_PKG_CONFIG=1 when calling make.
To build both static libbpf.a and shared libbpf.so:
$ cd src
$ make
To build only static libbpf.a library in directory build/ and install them together with libbpf headers in a staging directory root/:
$ cd src
$ mkdir build root
$ BUILD_STATIC_ONLY=y OBJDIR=build DESTDIR=root make install
To build both static libbpf.a and shared libbpf.so against a custom libelf dependency installed in /build/root/ and install them together with libbpf headers in a build directory /build/root/:
$ cd src
$ PKG_CONFIG_PATH=/build/root/lib64/pkgconfig DESTDIR=/build/root make install
License
This work is dual-licensed under BSD 2-clause license and GNU LGPL v2.1 license. You can choose between one of them if you use this work.
SPDX-License-Identifier: BSD-2-Clause OR LGPL-2.1