From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1Rc1Uz-00041A-Nm for garchives@archives.gentoo.org; Sat, 17 Dec 2011 21:08:53 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 13AF421C10E; Sat, 17 Dec 2011 21:08:40 +0000 (UTC) Received: from ironport2-out.teksavvy.com (ironport2-out.teksavvy.com [206.248.154.183]) by pigeon.gentoo.org (Postfix) with ESMTP id 05F0421C10E for ; Sat, 17 Dec 2011 21:07:34 +0000 (UTC) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvwEAGAD7U5FxIKd/2dsb2JhbABDq1aBBoIzHHImJTefcJ8RiGqCN2MEiDaETikBh0+FXogehFE X-IronPort-AV: E=Sophos;i="4.71,369,1320642000"; d="scan'208";a="152748555" Received: from 69-196-130-157.dsl.teksavvy.com (HELO waltdnes.org) ([69.196.130.157]) by ironport2-out.teksavvy.com with SMTP; 17 Dec 2011 16:07:33 -0500 Received: by waltdnes.org (sSMTP sendmail emulation); Sat, 17 Dec 2011 16:07:09 -0500 From: "Walter Dnes" Date: Sat, 17 Dec 2011 16:07:09 -0500 To: gentoo-user@lists.gentoo.org Subject: [gentoo-user] -march=native is *EXTREMELY* conservative Message-ID: <20111217210709.GA1740@waltdnes.org> 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: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-Archives-Salt: fd65679d-a851-4334-b048-f5ffe80146e4 X-Archives-Hash: 6ccbb750d08467d847d40279e59daa0c Here's the setup of my secondary machine.. It's a Dell Inspiron Desktop 530, with 2 gigs of ram, assembled and shipped August 2007. It has an Intel Core2 (*NOT* a "Core2 Duo") cpu. From /proc/cpuinfo... vendor_id : GenuineIntel cpu family : 6 model : 15 model name : Genuine Intel(R) CPU 2140 @ 1.60GHz stepping : 2 cpu MHz : 1595.660 cache size : 1024 KB Here are the cpu flags... waltdnes@d530 ~ $ grep flags /proc/cpuinfo flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc arch_perfmon pebs bts aperfmperf pni dtes64 monitor ds_cpl est tm2 ssse3 cx16 xtpr pdcm lahf_lm dts Then I ran "gcc -march=native -Q --help=target" and got a major shock. It's a long output listing of what -march=native thinks about my cpu. Here are some relevant items... -march= core2 -mmmx [disabled] -msse [disabled] -msse2 [disabled] -msse3 [disabled] -mssse3 [disabled] It properly identified the cpu as "core2". But mmx, sse, sse2, sse3 (aka pni), and ssse3 are disabled!!! The reason I dug into this was that I was trying to 1920x1080i streaming video from my HDHomerun TV tuner box. I originally used CFLAGS="-O2 -march=native -fomit-frame-pointer -pipe" when setting up the system. It could not handle 1920x1080i streaming TV video. After findinding out about "-native", I changed CFLAGS to... CFLAGS="-O2 -march=native -mmmx -msse -msse2 -msse3 -mssse3 -mfpmath=sse -fomit-frame-pointer -pipe" ...and emerged system and world and rebuilt the kernel. Now the onboard Intel GPU handles 1920x1080i flawlessly. As a matter of fact, it handles 1080p flawlessly. -- Walter Dnes