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Buildroot commitf7b8508e4fin 2021.08-rc1 added the libbpf package which contains the usage of the 'install_uapi_headers' make target to update toolchain headers older than kernel version 5.9. This does not work with per-package directories. Building this defconfig that includes all packages depending on libbpf: BR2_x86_64=y BR2_x86_rocketlake=y BR2_KERNEL_HEADERS_VERSION=y BR2_DEFAULT_KERNEL_VERSION="5.8.18" BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_5_8=y BR2_TOOLCHAIN_BUILDROOT_CXX=y BR2_PER_PACKAGE_DIRECTORIES=y BR2_PACKAGE_BPFTRACE=y BR2_PACKAGE_DPDK=y BR2_PACKAGE_IPROUTE2=y BR2_PACKAGE_HOST_PAHOLE=y on the 2026.02.x branch as of0be927b89ais broken: output/build/bpftrace-0.24.2/src/attached_probe.cpp: In static member function 'static bpftrace::Result<std::unique_ptr<bpftrace::AttachedIterProbe> > bpftrace::AttachedIterProbe::make(bpftrace::Probe&, const bpftrace::BpfProgram&, std::optional<int>)': output/build/bpftrace-0.24.2/src/attached_probe.cpp:1435:30: error: aggregate 'bpf_iter_link_info linfo' has incomplete type and cannot be defined 1435 | union bpf_iter_link_info linfo; libbpf overwrites kernel header files installed in $STAGING_DIR when they are too old by adding 'install_uapi_headers' as make target. In the case of per-package directories these header files are stored only in output/per-package/libbpf/. When output/per-package/bpftrace/ is populated, the content of output/per-package/ from other packages overwrites the header files installed by libbpf because the list of rsync'ed packages is sorted alphabetically: https://gitlab.com/buildroot.org/buildroot/-/blob/2026.02.1/package/pkg-generic.mk#L796 To prevent this problem let libbpf install the updated kernel headers in a new directory. Other packages need to find this directory. This mostly happens through pkg-config, but bpftrace doesn't use that: https://github.com/bpftrace/bpftrace/blob/v0.25.1/cmake/FindLibBpf.cmake#L9 Therefore, use a configure option in bpftrace to set the correct path. Please note that libbpf will add '/linux' to the path provided in $UAPIDIR: https://github.com/libbpf/libbpf/blob/v1.7.0/src/Makefile#L169 so the headers end up in the previously non-existing directory $(STAGING_DIR)/usr/include/bpf/linux/: $ find output/per-package/libbpf/host/x86_64-buildroot-linux-gnu/sysroot/ -iname bpf.h -exec ls -lao {} \; -rw-r--r-- 1 bernd 26434 25. Apr 13:15 output/per-package/libbpf/host/x86_64-buildroot-linux-gnu/sysroot/usr/include/bpf/bpf.h -rw-r--r-- 1 bernd 283012 25. Apr 13:15 output/per-package/libbpf/host/x86_64-buildroot-linux-gnu/sysroot/usr/include/bpf/linux/bpf.h -rw-r--r-- 12 bernd 160166 25. Apr 13:08 output/per-package/libbpf/host/x86_64-buildroot-linux-gnu/sysroot/usr/include/linux/bpf.h bpf.h with 283012 bytes is the update-to-date version needed for bpftrace: $ grep -m1 bpf_iter_link_info output/per-package/libbpf/host/x86_64-buildroot-linux-gnu/sysroot/usr/include/bpf/linux/bpf.h union bpf_iter_link_info { $ $ grep -m1 bpf_iter_link_info output/per-package/libbpf/host/x86_64-buildroot-linux-gnu/sysroot/usr/include/linux/bpf.h $ By adding '-I$(STAGING_DIR)/usr/include/bpf' to the CXXFLAGS of bpftrace its include finds the correct header: https://github.com/bpftrace/bpftrace/blob/v0.25.1/src/bpfprogram.cpp#L3 #include <linux/bpf.h> The dpdk package uses pkg-config` to detect libbpf and will use the updated .pc file: https://github.com/DPDK/dpdk/blob/v25.11/drivers/net/tap/bpf/meson.build#L7 The iproute2 package is not affected by the problem because it contains "matching sanitized kernel headers": https://git.kernel.org/pub/scm/network/iproute2/iproute2.git/tree/README?h=v6.17.0#n44 As a host package pahole is also not affected. Fixes: https://autobuild.buildroot.net/results/d8b/d8b416e40bf7bd019cd93e6f2d42c98fc12d4160/ Signed-off-by: Bernd Kuhls <bernd@kuhls.net> Signed-off-by: Arnout Vandecappelle <arnout@rnout.be> (cherry picked from commitf07fb2bcd2) Signed-off-by: Thomas Perale <thomas.perale@mind.be>
Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation. The documentation can be found in docs/manual. You can generate a text document with 'make manual-text' and read output/docs/manual/manual.text. Online documentation can be found at https://buildroot.org/docs.html To build and use the buildroot stuff, do the following: 1) run 'make menuconfig' 2) select the target architecture and the packages you wish to compile 3) run 'make' 4) wait while it compiles 5) find the kernel, bootloader, root filesystem, etc. in output/images You do not need to be root to build or run buildroot. Have fun! Buildroot comes with a basic configuration for a number of boards. Run 'make list-defconfigs' to view the list of provided configurations. Please feed suggestions, bug reports, insults, and bribes back to the buildroot mailing list: buildroot@buildroot.org You can also find us on #buildroot on OFTC IRC. If you would like to contribute patches, please read https://buildroot.org/manual.html#submitting-patches