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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BA335C021B8 for ; Tue, 4 Mar 2025 10:21:08 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tpPNv-0000bY-B7; Tue, 04 Mar 2025 05:20:23 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tpPNq-0000Zp-H1 for qemu-devel@nongnu.org; Tue, 04 Mar 2025 05:20:18 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tpPNn-0007LZ-NO for qemu-devel@nongnu.org; Tue, 04 Mar 2025 05:20:17 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741083610; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5CrI5udJio8AH2ajlJAW3Awj3cBKbPIDKwgqS3yJAFA=; b=Mh5AM5lw3QWw5zNQByj10llNyJMI6vLt/wQy0Ycwo0ZXaxgge3rFb4BFINwKLAwny1G/eW HinwwtVYYiIjqFtpZ5SJ1Dr9jh4abDQIpMBE0NR6Uu8uSuR/7zje+8AcXRjMV6BHOZr3Sy LZPsgQ9rQE7FGW/72Wtqpa+jwhBAxXE= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-31-Q9LRNADmPo28yx8GTk7klA-1; Tue, 04 Mar 2025 05:20:03 -0500 X-MC-Unique: Q9LRNADmPo28yx8GTk7klA-1 X-Mimecast-MFC-AGG-ID: Q9LRNADmPo28yx8GTk7klA_1741083602 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 60DCF1944EB8; Tue, 4 Mar 2025 10:20:01 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.109]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 041D119560A3; Tue, 4 Mar 2025 10:19:58 +0000 (UTC) Date: Tue, 4 Mar 2025 10:19:55 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Alex =?utf-8?Q?Benn=C3=A9e?= Cc: qemu-devel@nongnu.org, Paolo Bonzini , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [RFC PATCH] meson.build: add -gsplit-dwarf to default cflags Message-ID: References: <20250303221703.1291078-1-alex.bennee@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250303221703.1291078-1-alex.bennee@linaro.org> User-Agent: Mutt/2.2.13 (2024-03-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=-1, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Mar 03, 2025 at 10:17:03PM +0000, Alex Bennée wrote: > This option is supported by both gcc (since 4.7) and clang (since > 7.0). Not only does this make the linkers job easier by reducing the > amount of ELF it needs to parse it also reduces the total build size > quite considerably. In my case a default build went from 5.8G to 3.9G. I've not come across this option before, but the docs say ‘-gsplit-dwarf’ If DWARF debugging information is enabled, separate as much debugging information as possible into a separate output file with the extension ‘.dwo’. This option allows the build system to avoid linking files with debug information. To be useful, this option requires a debugger capable of reading ‘.dwo’ files. In Fedora and RHEL we build QEMU will full debug enabled, and then a feature of the distro RPM build config will post-process all ELF files to extract the debug info into files that we store under /usr/lib/debug. eg for /usr/bin/qemu-system-x86_64, we get a separate /usr/lib/debug/bin/qemu-system-x86_64-9.1.3-1.fc41.x86_64.debug, and tools like GDB, etc know to look for these separate files. When I test our RPM build process with this -gsplit-dwarf flag added, we fail to find any debug symbols in the QEMU binaries and thus the whole RPM package build aborts. IOW, if we add this to QEMU, my best guess currently is that we're going to have to revert it downstream. > > Signed-off-by: Alex Bennée > > --- > RFC: > - currently and RFC because it should also apply to test binaries > --- > meson.build | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/meson.build b/meson.build > index 4588bfd864..a936d1b422 100644 > --- a/meson.build > +++ b/meson.build > @@ -363,7 +363,7 @@ endforeach > > qemu_common_flags = [ > '-D_GNU_SOURCE', '-D_FILE_OFFSET_BITS=64', '-D_LARGEFILE_SOURCE', > - '-fno-strict-aliasing', '-fno-common', '-fwrapv' ] > + '-fno-strict-aliasing', '-fno-common', '-fwrapv', '-gsplit-dwarf' ] > qemu_cflags = [] > qemu_ldflags = [] > > -- > 2.39.5 > With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|