Re: [PATCH] bpftool: Fix failure with static linkage

[Stanislav Fomichev <stfomichev@xxxxxxxxx>]

On 12/04, Leo Yan wrote:
> When building perf with static linkage:
> 
>   make O=/build LDFLAGS="-static" -C tools/perf VF=1 DEBUG=1
>   ...
>   LINK    /build/util/bpf_skel/.tmp/bootstrap/bpftool
>   /usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/13/../../../x86_64-linux-gnu/libelf.a(elf_compress.o): in function `__libelf_compress':
>   (.text+0x113): undefined reference to `ZSTD_createCCtx'
>   /usr/bin/ld: (.text+0x2a9): undefined reference to `ZSTD_compressStream2'
>   /usr/bin/ld: (.text+0x2b4): undefined reference to `ZSTD_isError'
>   /usr/bin/ld: (.text+0x2db): undefined reference to `ZSTD_freeCCtx'
>   /usr/bin/ld: (.text+0x5a0): undefined reference to `ZSTD_compressStream2'
>   /usr/bin/ld: (.text+0x5ab): undefined reference to `ZSTD_isError'
>   /usr/bin/ld: (.text+0x6b9): undefined reference to `ZSTD_freeCCtx'
>   /usr/bin/ld: (.text+0x835): undefined reference to `ZSTD_freeCCtx'
>   /usr/bin/ld: (.text+0x86f): undefined reference to `ZSTD_freeCCtx'
>   /usr/bin/ld: (.text+0x91b): undefined reference to `ZSTD_freeCCtx'
>   /usr/bin/ld: (.text+0xa12): undefined reference to `ZSTD_freeCCtx'
>   /usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/13/../../../x86_64-linux-gnu/libelf.a(elf_compress.o): in function `__libelf_decompress':
>   (.text+0xbfc): undefined reference to `ZSTD_decompress'
>   /usr/bin/ld: (.text+0xc04): undefined reference to `ZSTD_isError'
>   /usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/13/../../../x86_64-linux-gnu/libelf.a(elf_compress.o): in function `__libelf_decompress_elf':
>   (.text+0xd45): undefined reference to `ZSTD_decompress'
>   /usr/bin/ld: (.text+0xd4d): undefined reference to `ZSTD_isError'
>   collect2: error: ld returned 1 exit status
> 
> Building bpftool with static linkage also fails with the same errors:
> 
>   make O=/build -C tools/bpf/bpftool/ V=1
> 
> To fix the issue, explicitly link libzstd.
> 
> Signed-off-by: Leo Yan <leo.yan@xxxxxxx>
> ---
>  tools/bpf/bpftool/Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
> index a4263dfb5e03..65b2671941e0 100644
> --- a/tools/bpf/bpftool/Makefile
> +++ b/tools/bpf/bpftool/Makefile
> @@ -130,8 +130,8 @@ include $(FEATURES_DUMP)
>  endif
>  endif
>  
> -LIBS = $(LIBBPF) -lelf -lz
> -LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf -lz
> +LIBS = $(LIBBPF) -lelf -lz -lzstd
> +LIBS_BOOTSTRAP = $(LIBBPF_BOOTSTRAP) -lelf -lz -lzstd
>  ifeq ($(feature-libcap), 1)
>  CFLAGS += -DUSE_LIBCAP
>  LIBS += -lcap
> -- 
> 2.34.1
> 

I'm not sure we 'offically' support -static builds, but this seems to be
ok. Tangential: maybe time to switch to pkg-config for bpftool? IIRC,
there is some flag to query for static lib dependencies... Will leave
it up to Quentin.