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=-3.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 86711C388F7 for ; Wed, 4 Nov 2020 00:00:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47CB2223BD for ; Wed, 4 Nov 2020 00:00:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NCaSGxD2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728431AbgKDAAU (ORCPT ); Tue, 3 Nov 2020 19:00:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726709AbgKDAAU (ORCPT ); Tue, 3 Nov 2020 19:00:20 -0500 Received: from mail-qv1-xf30.google.com (mail-qv1-xf30.google.com [IPv6:2607:f8b0:4864:20::f30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 234ECC0613D1; Tue, 3 Nov 2020 16:00:20 -0800 (PST) Received: by mail-qv1-xf30.google.com with SMTP id e5so5301488qvr.2; Tue, 03 Nov 2020 16:00:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=sBlEcrQKMaPe+KohbddbaWe4TK9yPL+Wt7MWMnxm1hI=; b=NCaSGxD27+WLCPQ8aOu6r4PFOO2xHUp7wreCeTIAP09iyqv3Kqb2mmRhyHTW9dwlZx 8DQQj4/4aEA2VTYY2hwSxw+em/hdm/eSZGupAeMSZrYaHt58q+hqBxu5bQPL8KXb6fhm m00AuQ1fthBiebdOM4ZKPUKafSR5aDGAh8oASQygXzMvBvyALSxv/fxPN33WaWNkNFIb WsSCIGYbSc4fSTx/cKPO2wS6lWeiVKJ5/O0a1LytypLUpQHvQohdzSTu5yGq0rf78kZz Tfrd7yr4QPzYaUEJXtcyk8mR7dZLYW16oKGYtcbbzjBmutPAAvAgRwhwiYOh3Cuu03my ai8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:date:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=sBlEcrQKMaPe+KohbddbaWe4TK9yPL+Wt7MWMnxm1hI=; b=BLVBA/LKrUH/ftWf2GSnpvBYlMTl5afsP3cY6XrbvfWtdvzekn9f6PpwwzE6LTUiUG imQMzrOntJgGnrOEa73HZ4oYTLU/d+uuz3yIu2MSymPj1wPGPSTvS0q/hepXk872xBkv QrILrpIce/oPQMvWIOFTBpR66LCkFuU1IPvYRI6/aCQjRYIZUd95jpasplM226vGLzaT GMswkjWZPyxlN31hgQy7ht3WvJ1/VpEdo80J0PhA/guq64SqhjTn1ek/IgTFagnu2nT9 G438m6fQZAlRZc8lsrcWmO+f7MGivvIS+cAaELLZnmEdMmjGiKFSFloGUCTRSeOfB/v3 QZrA== X-Gm-Message-State: AOAM533fsdSHoNdj05SYsUC7aAoP6aiXor5ByAXPnh748rvXyO5gVkVm JuNFQvE2UCPXUJwKimBWlavht4H1Lxdxww== X-Google-Smtp-Source: ABdhPJxRtdccN7P/DQ2aft9NGU7eOKa1g3H4JMubiqLsf2VeppboaQTlwLTSVvaZccDUCv/W3ONIBQ== X-Received: by 2002:a05:6214:9d2:: with SMTP id dp18mr1033766qvb.29.1604448019071; Tue, 03 Nov 2020 16:00:19 -0800 (PST) Received: from rani.riverdale.lan ([2001:470:1f07:5f3::b55f]) by smtp.gmail.com with ESMTPSA id k17sm516851qki.5.2020.11.03.16.00.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Nov 2020 16:00:18 -0800 (PST) Sender: Arvind Sankar From: Arvind Sankar X-Google-Original-From: Arvind Sankar Date: Tue, 3 Nov 2020 19:00:16 -0500 To: Nick Desaulniers Cc: Masahiro Yamada , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com, linux-toolchains@vger.kernel.org Subject: Re: [PATCH] Kbuild: implement support for DWARF5 Message-ID: <20201104000016.GA2399651@rani.riverdale.lan> References: <20201022012106.1875129-1-ndesaulniers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201022012106.1875129-1-ndesaulniers@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org On Wed, Oct 21, 2020 at 06:21:06PM -0700, Nick Desaulniers wrote: > DWARF5 is the latest standard of the DWARF debug info format. > > Feature detection of DWARF5 is onerous, especially given that we've > removed $(AS), so we must query $(CC) for DWARF5 assembler directive > support. Further -gdwarf-X where X is an unsupported value doesn't > produce an error in $(CC). GNU `as` only recently gained support for > specifying -gdwarf-5. Do you have more details here? On godbolt.org, gcc does report an error for unsupported dwarf versions. https://godbolt.org/z/G35798 gcc does not seem to pass the -gdwarf-* options to the assembler when compiling C source. For assembler, gcc will pass an appropriate option depending on the version of binutils it was configured with: if the assembler doesn't support dwarf-5 it can call it with --gdwarf2 for eg. If the user is using a properly configured toolchain it doesn't look like it should be an issue to just use cc-option?