Re: [PATCH bpf-next] libbpf: add zlib as a dependency in pkg-config template

[Yonghong Song <yhs@fb.com>]

On 12/16/19 10:38 AM, Andrii Nakryiko wrote:
> List zlib as another dependency of libbpf in pkg-config template.
> Verified it is correctly resolved to proper -lz flag:
> 
> $ make DESTDIR=/tmp/libbpf-install install
> $ pkg-config --libs /tmp/libbpf-install/usr/local/lib64/pkgconfig/libbpf.pc
> -L/usr/local/lib64 -lbpf
> $ pkg-config --libs --static /tmp/libbpf-install/usr/local/lib64/pkgconfig/libbpf.pc
> -L/usr/local/lib64 -lbpf -lelf -lz

Even without this patch, I already got -lz for static link libraries:

-bash-4.4$ cat libbpf.pc.template
...
Requires.private: libelf
...
-bash-4.4$ pkg-config --libs --static 
/tmp/libbpf-install/usr/local/lib64/pkgconfig/libbpf.pc
-L/usr/local/lib64 -lbpf -lelf -lz

libelf depending on zlib. Maybe -lz is introduced due to libelf.

But in any case, add explicit dependency to zlib from libbpf probably
a good thing since libbpf directly uses its API functions.

Acked-by: Yonghong Song <yhs@fb.com>


[...]
> diff --git a/tools/lib/bpf/libbpf.pc.template b/tools/lib/bpf/libbpf.pc.template
> index ac17fcef2108..b45ed534bdfb 100644
> --- a/tools/lib/bpf/libbpf.pc.template
> +++ b/tools/lib/bpf/libbpf.pc.template
> @@ -8,5 +8,5 @@ Name: libbpf
>   Description: BPF library
>   Version: @VERSION@
>   Libs: -L${libdir} -lbpf
> -Requires.private: libelf
> +Requires.private: libelf zlib
>   Cflags: -I${includedir}
>