Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20200122000110.GA310073@chrisdown.name>
In-Reply-To: <20200122000110.GA310073@chrisdown.name>
From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Tue, 21 Jan 2020 16:05:53 -0800
Message-ID: <CAEf4BzZnOFfw102XiG4yJNTR63fT-_QHFU7QSu2apvrz=i_TWQ@mail.gmail.com>
Subject: Re: [PATCH v2] bpf: btf: Always output invariant hit in pahole DWARF
 to BTF transform
To:     Chris Down <chris@chrisdown.name>
Cc:     bpf <bpf@vger.kernel.org>, Networking <netdev@vger.kernel.org>,
        Stanislav Fomichev <sdf@google.com>,
        Andrii Nakryiko <andriin@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        open list <linux-kernel@vger.kernel.org>,
        Kernel Team <kernel-team@fb.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Jan 21, 2020 at 4:01 PM Chris Down <chris@chrisdown.name> wrote:
>
> When trying to compile with CONFIG_DEBUG_INFO_BTF enabled, I got this
> error:
>
>     % make -s
>     Failed to generate BTF for vmlinux
>     Try to disable CONFIG_DEBUG_INFO_BTF
>     make[3]: *** [vmlinux] Error 1
>
> Compiling again without -s shows the true error (that pahole is
> missing), but since this is fatal, we should show the error
> unconditionally on stderr as well, not silence it using the `info`
> function. With this patch:
>
>     % make -s
>     BTF: .tmp_vmlinux.btf: pahole (pahole) is not available
>     Failed to generate BTF for vmlinux
>     Try to disable CONFIG_DEBUG_INFO_BTF
>     make[3]: *** [vmlinux] Error 1
>
> Signed-off-by: Chris Down <chris@chrisdown.name>
> Cc: Stanislav Fomichev <sdf@google.com>
> Cc: Andrii Nakryiko <andriin@fb.com>
> Cc: John Fastabend <john.fastabend@gmail.com>
> Cc: linux-kernel@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Cc: bpf@vger.kernel.org
> Cc: kernel-team@fb.com
> ---
>  scripts/link-vmlinux.sh | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>

Looks great, thanks!

Acked-by: Andrii Nakryiko <andriin@fb.com>

> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index c287ad9b3a67..bbe9be2bf5ff 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -108,13 +108,13 @@ gen_btf()
>         local bin_arch
>
>         if ! [ -x "$(command -v ${PAHOLE})" ]; then
> -               info "BTF" "${1}: pahole (${PAHOLE}) is not available"
> +               echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
>                 return 1
>         fi
>
>         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
>         if [ "${pahole_ver}" -lt "113" ]; then
> -               info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
> +               echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
>                 return 1
>         fi
>
> --
> 2.25.0
>