Re: [PATCH] perf tools: Fix dynamic libbpf link

[Justin Forbes]

On Sat, May 8, 2021 at 3:50 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> Justin reported broken build with LIBBPF_DYNAMIC=1.
>
> When linking libbpf dynamically we need to use perf's
> hashmap object, because it's not exported in libbpf.so
> (only in libbpf.a).
>
> Following build is now passing:
>
>   $ make LIBBPF_DYNAMIC=1
>     BUILD:   Doing 'make -j8' parallel build
>     ...
>   $ ldd perf | grep libbpf
>         libbpf.so.0 => /lib64/libbpf.so.0 (0x00007fa7630db000)
>
> Fixes: eee19501926d ("perf tools: Grab a copy of libbpf's hashmap")
> Cc: Ian Rogers <irogers@xxxxxxxxxx>
> Reported-by: Justin M. Forbes <jforbes@xxxxxxxxxx>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---

This patch fixes it for me.

Tested-by: Justin M. Forbes <jforbes@xxxxxxxxxx>

>  tools/perf/Makefile.config | 1 +
>  tools/perf/util/Build      | 7 +++++++
>  2 files changed, 8 insertions(+)
>
> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 7b195e16040e..dacd16874d3d 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -546,6 +546,7 @@ ifndef NO_LIBELF
>        ifdef LIBBPF_DYNAMIC
>          ifeq ($(feature-libbpf), 1)
>            EXTLIBS += -lbpf
> +          $(call detected,CONFIG_LIBBPF_DYNAMIC)
>          else
>            dummy := $(error Error: No libbpf devel library found, please install libbpf-devel);
>          endif
> diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> index e27a551acd3a..95e15d1035ab 100644
> --- a/tools/perf/util/Build
> +++ b/tools/perf/util/Build
> @@ -145,7 +145,14 @@ perf-$(CONFIG_LIBELF) += symbol-elf.o
>  perf-$(CONFIG_LIBELF) += probe-file.o
>  perf-$(CONFIG_LIBELF) += probe-event.o
>
> +ifdef CONFIG_LIBBPF_DYNAMIC
> +  hashmap := 1
> +endif
>  ifndef CONFIG_LIBBPF
> +  hashmap := 1
> +endif
> +
> +ifdef hashmap
>  perf-y += hashmap.o
>  endif
>
> --
> 2.31.1
>