Messages in this thread | | | Date | Fri, 3 Dec 2021 10:10:42 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Building perf with BUILD_BPF_SKEL=1 by default |
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Hi Song,
So I'm changing all my containers to build with BUILD_BPF_SKEL=1 to then make this the default, so far older containers fail either because the clang available is too old, so I've added a NO_BUILD_BPF_SKEL=1 env var to disable that in those containers and then there is this other case where clang is recent enough but:
util/bpf_skel/bperf_leader.bpf.c:13:20: error: use of undeclared identifier 'BPF_F_PRESERVE_ELEMS' __uint(map_flags, BPF_F_PRESERVE_ELEMS);
Because the system's /usr/include/linux/bpf.h doesn't have that BPF_F_PRESERVE_ELEMS enum entry.
These are enums to make them available via BTF, but then I can't use the:
#ifdef BPF_F_PRESERVE_ELEMS #define BPF_F_PRESERVE_ELEMS (1U << 11) #endif
approach.
But then we _have_ it in the tools/include/uapi/linux/bpf.h we ship:
$ grep BPF_F_PRESERVE_ELEMS tools/include/uapi/linux/bpf.h BPF_F_PRESERVE_ELEMS = (1U << 11), $
so we need to switch to using it somehow, this way we can build in more systems and make bperf and other BPF enabled features.
From a quick look I couldn't find where to add $(sourcedir)/tools/include/uapi/ to the include path used to build util/bpf_skel/bperf_leader.bpf.c, should be easy, can you take a look?
Thanks,
- Arnaldo
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