From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 9FAD3138C9D for ; Thu, 30 Apr 2015 17:45:35 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 3D11EE0841; Thu, 30 Apr 2015 17:45:29 +0000 (UTC) Received: from smtp.gentoo.org (smtp.gentoo.org [140.211.166.183]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 2A345E0653 for ; Thu, 30 Apr 2015 17:45:28 +0000 (UTC) Received: from localhost (sloan0.ut.mephi.ru [85.143.112.33]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: bircoph) by smtp.gentoo.org (Postfix) with ESMTPSA id 71CD5340B73 for ; Thu, 30 Apr 2015 17:45:25 +0000 (UTC) Date: Thu, 30 Apr 2015 20:45:18 +0300 From: Andrew Savchenko To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] CFLAGs for kernel compilation Message-Id: <20150430204518.b89e4a39cab48a9cdf339259@gentoo.org> In-Reply-To: <554257AE.8020503@googlemail.com> References: <5540C101.70906@ramses-pyramidenbau.de> <554257AE.8020503@googlemail.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.25; i686-pc-linux-gnu) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pgp-signature"; micalg="PGP-SHA512"; boundary="Signature=_Thu__30_Apr_2015_20_45_18_+0300_jzbMS9VJ0Zy72CPi" X-Archives-Salt: 02839bf2-a56c-4a03-a200-1e78e9dd570b X-Archives-Hash: 2de3e52d3da9c382c846c2b6383ccaea --Signature=_Thu__30_Apr_2015_20_45_18_+0300_jzbMS9VJ0Zy72CPi Content-Type: text/plain; charset=US-ASCII Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, On Thu, 30 Apr 2015 18:26:22 +0200 Volker Armin Hemmann wrote: > That simple. The kernel is too important and the people programming it > know what they are doing. Don't set anything. It is retarded. > > > > - I don't like invoking 'CFLAGS=3D"-O2 -march=3Dfoo"make' > > - I don't want to set CFLAGS as a persistent environment variable. > > - I don't want to modify the kernel Makefile > > > > Does it actually make sense to set an optimization level and -march? >=20 > no While I completely agree with you that kernel CFLAGS should not be randomly tampered with, I can't agree that -march itself is useless. Tests and results are available here: https://github.com/graysky2/kernel_gcc_patch Optimization is a very powerful tool if taken with care. Of course it may lead to a disastrous result if mindlessly used. Best regards, Andrew Savchenko --Signature=_Thu__30_Apr_2015_20_45_18_+0300_jzbMS9VJ0Zy72CPi Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCgAGBQJVQmovAAoJEPZTWjO6HuSNKm4QALk70ZW6UN5WA/CrZ2fNAB62 dMIa1W5Re+2ZhfaSgezzX3X89vt9BAOS52dQHjec41AYxZaCt4+sAY3/yGNJMMsU SFaYFrpjysVZzI1U7yPk7VTbYrvLSPBWrPwp76Z/ugK4/L5hNYquuHT105tYMF1P t0qL0jbAqWgfmfjINSs1r58UY6v+CjQa0BTHVuqWGjmAtYPSsQBo9BRlMqKsrs2e 0BQpCleNBeQn1L0gHFDjAZY/etWi+Zyk27vtu2heYeR3kykBwmCSaVyLS1lghPFb m53rqtMDuUZBKvZlFzagVEo6KCu0ApuzvcBik94bUVZ4MByVpSooedKSdUXExUeQ z9d6GFcda772gfuM1kj7Ii/PqkagFOobOy9NFsYxC9EeoNPpM0k5BzKNPsjn6AYo BJmMQywf0G+LQG58wV6+A9mcNjiG8qFERUQf/wrPDG3el2nKUjDPyE3HgR3lAoyQ q71V6lVF+H76HlGQzoQOYjuiKcO0nssWW3sa3LVYGjhvniwrSA6pey0oMQFYysdT 1IUy49yA7FKviwB/XF+v2wR/6Iah8XB61rDZCUSNRi7a3nApxvgtaajACXaVruUt 7ZDBh1mCbej5HEk1wXm2RdJ1VZTNxFTC0zGdi77N8U+cBFu1MxE7KzUaQJt+ZjZu Lze0P56VVYL7Rtd+2JkL =rl+v -----END PGP SIGNATURE----- --Signature=_Thu__30_Apr_2015_20_45_18_+0300_jzbMS9VJ0Zy72CPi--