From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 789DBC4361B for ; Mon, 7 Dec 2020 17:17:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43F342388D for ; Mon, 7 Dec 2020 17:17:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727022AbgLGRRw (ORCPT ); Mon, 7 Dec 2020 12:17:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727073AbgLGRRv (ORCPT ); Mon, 7 Dec 2020 12:17:51 -0500 Received: from mail-lj1-x243.google.com (mail-lj1-x243.google.com [IPv6:2a00:1450:4864:20::243]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 151BAC061749 for ; Mon, 7 Dec 2020 09:17:11 -0800 (PST) Received: by mail-lj1-x243.google.com with SMTP id e7so5563232ljg.10 for ; Mon, 07 Dec 2020 09:17:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=CEeZ2nmwSpyuPT6kc3jLgcOFT3oyPRfJO0jz7F9f9kg=; b=HB4V+kYfgV3pvqslRz8AVGRH7QWGP8KktexZ6gcHM6DI2YVdZy4kKM/bEKtIUJdTRD vik1wl9mBy7hfd8QSfze/YQm04Ite26vlAmYFEqNJ/yP9ydhQ6nhncDes9D64eW8z4hp hA5nX8AixoXE1I88114eMknZ0jStKCULTuzYKDCBROB+obDdAemDcIdnvGyLIFPwkcOn GV6VG6Q9mDh9NBr8D1IQZmqWCKxAmPqk5TZh//JLdKioBHZFMb27gIFa+YJibDJXuWCr sJRd8/MTXhS1ddD4ALIZXbnqC7+gGNwg1XIujaSXxbZGpfheRf+56s3iO3t+6MrXJ3k8 S3/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=CEeZ2nmwSpyuPT6kc3jLgcOFT3oyPRfJO0jz7F9f9kg=; b=LXn8FqvX22YCWnv19E0roQnwKdYF29zy/sOIQMosOzGakcCmvBUo/ySF1zP3hJBWR9 PAW5hchP3fA50pe20xDT+J/Dv6HecfQFCSq6c+ZBinSfUB7BFP3X4ezn4q2o7O5WvR6m 86BJodm2srGIzMjG5NNJUNzwW1Se+OqYq6soQN5EDBrYP8yuQlnpnKRJ9VzMpWWB5xAs lEEEr2aFH/8vno1AXcK+q0n9uOeT6RB/9LvnEgx809F2Mm3Yo3pnUce3aJ9+vh2GHToC 8jyubH3GxSxFvGga271zdoTj9JvOEOvE/CRw92k0HWH2SSDg7Rf1A56E4L9QhqWl7OuP sP8Q== X-Gm-Message-State: AOAM532RA5IGh+MescuFAdf7UyC1s7vDbbLY+xvuW5yMJ/vkHlLgENkP q0XodT6EBzxxek3LTEAMVaBYRCWzBbLAs+svFTE= X-Google-Smtp-Source: ABdhPJzkhNeQVjnwnRdfJBlHKVgajySIgQkToA241XKhTPJeF2JpizEXTzb2zs8N/74uhu1ePzlkipaSF6BViA9Z34M= X-Received: by 2002:a2e:9681:: with SMTP id q1mr9142628lji.2.1607361429613; Mon, 07 Dec 2020 09:17:09 -0800 (PST) MIME-Version: 1.0 References: <87lfeebwpu.fsf@toke.dk> <10679e62-50a2-4c01-31d2-cb79c01e4cbf@fb.com> <87r1o59aoc.fsf@toke.dk> <6801fcdb-932e-c185-22db-89987099b553@fb.com> <875z5d7ufl.fsf@toke.dk> <878sa9619d.fsf@toke.dk> <874kkx5zl5.fsf@toke.dk> In-Reply-To: <874kkx5zl5.fsf@toke.dk> From: Alexei Starovoitov Date: Mon, 7 Dec 2020 09:16:57 -0800 Message-ID: Subject: Re: Latest libbpf fails to load programs compiled with old LLVM To: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Cc: Andrii Nakryiko , Yonghong Song , bpf Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, Dec 7, 2020 at 8:51 AM Toke H=C3=B8iland-J=C3=B8rgensen wrote: > > Alexei Starovoitov writes: > > > On Mon, Dec 7, 2020 at 8:15 AM Toke H=C3=B8iland-J=C3=B8rgensen wrote: > >> > >> Alexei Starovoitov writes: > >> > >> > On Mon, Dec 7, 2020 at 3:03 AM Toke H=C3=B8iland-J=C3=B8rgensen wrote: > >> >> > >> >> Wait, what? This is a regression that *breaks people's programs* on > >> >> compiler versions that are still very much in the wild! I mean, fin= e if > >> >> you don't want to support new features on such files, but then sure= ly we > >> >> can at least revert back to the old behaviour? > >> > > >> > Those folks that care about compiling with old llvm would have to st= ick > >> > to whatever loader they have instead of using libbpf. > >> > It's not a backward compatibility breakage. > >> > >> What? It's a change in libbpf that breaks loading of existing BPF obje= ct > >> files that were working (with libbpf) before. If that's not a backward > >> compatibility break then that term has lost all meaning. > > > > The user space library is not a kernel. > > The library will change its interface. It will remove functions, featur= es, etc. > > That's what .map is for. > > Right, OK, so how do I use .map to get the old behaviour here? That's > all I'm asking for, really... Fix old llvm. The users would have to upgrade either from llvm 7.x to 7.x+1 or to llvm 10+.