Re: [PATCH bpf-next v2] bpftool: Resolve libcrypto link flags via pkg-config

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The logic to conditionally pass `--static` to `pkg-config` only checks `EXTRA_LDFLAGS`, missing static builds requested via `LDFLAGS`.
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commit c4bd62b29823641ce51fa6b07b88d88891141b01
Author: Hadrien Patte <hadrien.patte@protonmail.com>

bpftool: Resolve libcrypto link flags via pkg-config

This commit resolves libcrypto link flags for bpftool via pkg-config to correctly
pull in transitive dependencies like libjitterentropy for static builds. It also
adds a fallback to plain -lcrypto if pkg-config is not available.

> diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
> --- a/tools/bpf/bpftool/Makefile
> +++ b/tools/bpf/bpftool/Makefile
[ ... ]
> @@ -103,7 +103,35 @@ SKIP_LLVM ?=
>  SKIP_LIBBFD ?=
>  SKIP_CRYPTO ?=
>  ifneq ($(SKIP_CRYPTO),1)
> -  CRYPTO_LIBS := -lcrypto
> +  PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config
> +  HOSTPKG_CONFIG ?= pkg-config
[ ... ]
> +  # Resolve libcrypto link flags via pkg-config when available, so transitive
> +  # dependencies (e.g. libjitterentropy on distros where libcrypto.a
> +  # references it) are included for static builds. Pass --static when the
> +  # user requested a static build via EXTRA_LDFLAGS=-static.
> +  ifneq ($(filter -static,$(EXTRA_LDFLAGS)),)

If a user requests a static build using LDFLAGS=-static instead of
EXTRA_LDFLAGS=-static, will this check miss it?

The Makefile natively supports passing flags directly via standard LDFLAGS
and aggregates them. By only checking EXTRA_LDFLAGS here, pkg-config might
omit the --static flag when LDFLAGS is used directly. This could drop
transitive dependencies and cause the build to fail with undefined
references.

Would it be better to check LDFLAGS as well?

> +    PKG_CONFIG_LIBCRYPTO := --libs --static libcrypto
> +  else
> +    PKG_CONFIG_LIBCRYPTO := --libs libcrypto
> +  endif

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Sashiko AI review · https://sashiko.dev/#/patchset/20260501224346.12765-1-hadrien.patte@protonmail.com?part=1