From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dan.rpsys.net (5751f4a1.skybroadband.com [87.81.244.161]) by mail.openembedded.org (Postfix) with ESMTP id 92004736B6 for ; Mon, 30 Mar 2015 21:43:40 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by dan.rpsys.net (8.14.4/8.14.4/Debian-4.1ubuntu1) with ESMTP id t2ULhfSE002092; Mon, 30 Mar 2015 22:43:41 +0100 Received: from dan.rpsys.net ([127.0.0.1]) by localhost (dan.rpsys.net [127.0.0.1]) (amavisd-new, port 10024) with LMTP id MBGsZV4cktIL; Mon, 30 Mar 2015 22:43:41 +0100 (BST) Received: from [192.168.3.10] ([192.168.3.10]) (authenticated bits=0) by dan.rpsys.net (8.14.4/8.14.4/Debian-4.1ubuntu1) with ESMTP id t2ULhS2x002075 (version=TLSv1/SSLv3 cipher=AES128-GCM-SHA256 bits=128 verify=NOT); Mon, 30 Mar 2015 22:43:40 +0100 Message-ID: <1427751808.14020.327.camel@linuxfoundation.org> From: Richard Purdie To: Mark Hatle Date: Mon, 30 Mar 2015 22:43:28 +0100 In-Reply-To: <5519B425.1040906@windriver.com> References: <1427747268.14020.326.camel@linuxfoundation.org> <5519B425.1040906@windriver.com> X-Mailer: Evolution 3.12.10-0ubuntu1~14.10.1 Mime-Version: 1.0 Cc: openembedded-core@lists.openembedded.org Subject: Re: Verification on how TARGET_CFLAGS is set X-BeenThere: openembedded-core@lists.openembedded.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Patches and discussions about the oe-core layer List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 30 Mar 2015 21:43:46 -0000 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit On Mon, 2015-03-30 at 15:37 -0500, Mark Hatle wrote: > On 3/30/15 3:27 PM, Richard Purdie wrote: > > On Mon, 2015-03-30 at 13:09 +0000, Bryan Evenson wrote: > >> I am about to upgrade to the dizzy branch. I have a built a bootable > >> image on my test build machine, and now I'm going to be applying > >> changes to the system I use for building production images. I'm > >> planning on deleting my tmp directory to force a re-build of > >> everything. Since I'm rebuilding everything anyway, I'm taking a > >> deeper look at the CFLAGS related settings and I'm getting a little > >> lost in the logic. I'd like to verify these settings before I start > >> rebuilding everything. > >> > >> If I'm following the default logic correctly in bitbake.conf, by > >> default TARGET_CFLAGS will be set to "-O2 -pipe -g > >> -feliminate-unused-debug-types". I want the default TARGET_CFLAGS for > >> my production image to be "-O2 -pipe". What's the suggested variable > >> to change, and where, to get this final value? Do I set TARGET_CFLAGS > >> directly, or do I set SELECTED_OPTIMIZATIONS or even > >> FULL_OPTIMIZATIONS? Do I set it in local.conf or should I be setting > >> it somewhere else? > > > > If I remember rightly, you need the -g option there to generate the -dbg > > packages correctly. The target system binaries won't change since we > > separate out the debug data into separate files as part of the packaging > > process. > > > > You therefore can gain some build performance from turning that off but > > your runtime won't alter much (other than the debuglink ID which is a > > few bytes). > > I strongly caution people against removing '-g' from their production builds. > If you do, you will no longer have any way to do any type of production/field > debug. As Richard indicated the -g will cause the symbols and debug information > to get separated into special -dbg packages that you generally don't distribute > on a production device -- but those same -dbg package (preserved) can be later > used for debugging of production devices. > > This is why the default is what it is. > > The difference in executable size between -g (split debug) and w/o -g, is > usually around 15 - 30 bytes. Roughly the length of the path to the executable > and/or library plus ".debug/" (7 characters) Are you sure its even that? I thought it was literally just the debug ID code and the paths to debug were assumed by the debug tools which would search several locations for a matching ID? Cheers, Richard