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;
Date:   Wed, 19 Feb 2020 18:03:48 +0100
From:   Jesper Dangaard Brouer <brouer@redhat.com>
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     Andrii Nakryiko <andrii.nakryiko@gmail.com>,
        Andrii Nakryiko <andriin@fb.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        BPF-dev-list <bpf@vger.kernel.org>,
        Daniel Borkmann <borkmann@iogearbox.net>,
        David Miller <davem@davemloft.net>,
        LKML <linux-kernel@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Anders Roxell <anders.roxell@linaro.org>,
        Toke =?UTF-8?B?SMO4aWxhbmQtSsO4cmdlbnNlbg==?= <toke@redhat.com>,
        brouer@redhat.com
Subject: Re: Kernel 5.5.4 build fail for BPF-selftests with latest LLVM
Message-ID: <20200219180348.40393e28@carbon>
In-Reply-To: <CAADnVQKQRKtDz0Boy=-cudc4eKGXB-yParGZv6qvYcQR4uMUQQ@mail.gmail.com>
References: <20200219133012.7cb6ac9e@carbon>
        <CAADnVQKQRKtDz0Boy=-cudc4eKGXB-yParGZv6qvYcQR4uMUQQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, 19 Feb 2020 08:41:27 -0800
Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:

> On Wed, Feb 19, 2020 at 4:30 AM Jesper Dangaard Brouer
> <brouer@redhat.com> wrote:
> >
> > I'm willing to help out, such that we can do either version or feature
> > detection, to either skip compiling specific test programs or at least
> > give users a proper warning of they are using a too "old" LLVM version.  
> ...
> > progs/test_core_reloc_bitfields_probed.c:47:13: error: use of unknown builtin '__builtin_preserve_field_info' [-Wimplicit-function-declaration]
> >         out->ub1 = BPF_CORE_READ_BITFIELD_PROBED(in, ub1);  
> 
> imo this is proper warning message already.

This is an error, not a warning.  The build breaks as the make process stops.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer