Re: [BUG] bpftool: Build failure due to opensslv.h

[Namhyung Kim <namhyung@kernel.org>]

On Tue, Oct 28, 2025 at 10:05:52AM +0100, Quentin Monnet wrote:
> 2025-10-27 11:27 UTC-0700 ~ Namhyung Kim <namhyung@kernel.org>
> > On Mon, Oct 27, 2025 at 11:41:01AM +0000, Quentin Monnet wrote:
> >> 2025-10-26 21:01 UTC-0700 ~ Namhyung Kim <namhyung@kernel.org>
> >>> Hello,
> >>>
> >>> I'm seeing a build failure like below in Fedora 40 and others.  I'm not
> >>> sure if it's reported already but it failed to build perf tools due to
> >>> errors in the bootstrap bpftool.
> >>>
> >>>     CC      /build/util/bpf_skel/.tmp/bootstrap/sign.o
> >>>   sign.c:16:10: fatal error: openssl/opensslv.h: No such file or directory
> >>>      16 | #include <openssl/opensslv.h>
> >>>         |          ^~~~~~~~~~~~~~~~~~~~
> >>>   compilation terminated.
> >>>   make[3]: *** [Makefile:256: /build/util/bpf_skel/.tmp/bootstrap/sign.o] Error 1
> >>>   make[3]: *** Waiting for unfinished jobs....
> >>>   make[2]: *** [Makefile.perf:1213: /build/util/bpf_skel/.tmp/bootstrap/bpftool] Error 2
> >>>   make[1]: *** [Makefile.perf:289: sub-make] Error 2
> >>>   make: *** [Makefile:76: all] Error 2
> >>>
> >>> I think it's from the recent signing change.  I'm not familiar with
> >>> openssl but I guess there's a proper feature check for it.  Is this a
> >>> known issue?
> >>
> >>
> >> Hi Namhyung,
> > 
> > Hello!
> > 
> >>
> >> This looks related to the program signing change indeed, commit
> >> 40863f4d6ef2 ("bpftool: Add support for signing BPF programs")
> >> introduced a dependency on OpenSSL's development headers for bpftool.
> >> It's not gated behind a feature check. On Fedora, I think the headers
> >> come with openssl-devel, do you have this package installed?
> > 
> > No I don't, but I guess it should be able to build on such systems.  Or
> > is it required for bpftool?  Anyway I feel like it should have a feature
> > check and appropriate error messages.
> > 
> 
> +Cc KP
> 
> We usually have feature checks when optional features bring in new
> dependencies for bpftool, but we haven't discussed it this time. My
> understanding was that program signing is important enough that it
> should always be present in newer versions of bpftool, making OpenSSL
> one of the required dependencies going forward.

Yeah, the problem is that it also affects to perf build.

> 
> We don't currently have feature checks to tell when required
> dependencies are missing for bpftool (it's just the build failing, in
> that case). I know perf does a great job at it, we could look into it
> for bpftool, too.

It's in the tools/build directory. :)

Thanks,
Namhyung