From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay1.mentorg.com ([192.94.38.131]) by linuxtogo.org with esmtp (Exim 4.72) (envelope-from ) id 1QcKj2-0002wp-SU for openembedded-core@lists.openembedded.org; Thu, 30 Jun 2011 19:08:25 +0200 Received: from svr-orw-exc-10.mgc.mentorg.com ([147.34.98.58]) by relay1.mentorg.com with esmtp id 1QcJhM-0007Cc-9L from Tom_Rini@mentor.com for openembedded-core@lists.openembedded.org; Thu, 30 Jun 2011 09:02:36 -0700 Received: from SVR-ORW-FEM-04.mgc.mentorg.com ([147.34.97.41]) by SVR-ORW-EXC-10.mgc.mentorg.com with Microsoft SMTPSVC(6.0.3790.4675); Thu, 30 Jun 2011 09:02:03 -0700 Received: from [172.30.80.212] (147.34.91.1) by svr-orw-fem-04.mgc.mentorg.com (147.34.97.41) with Microsoft SMTP Server id 14.1.289.1; Thu, 30 Jun 2011 09:02:35 -0700 Message-ID: <4E0C9E14.4040209@mentor.com> Date: Thu, 30 Jun 2011 09:02:28 -0700 From: Tom Rini Organization: Mentor Graphics Corporation User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.17) Gecko/20110424 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: References: <4E0A1136.7030402@linux.intel.com> In-Reply-To: <4E0A1136.7030402@linux.intel.com> X-Enigmail-Version: 1.1.1 X-OriginalArrivalTime: 30 Jun 2011 16:02:03.0608 (UTC) FILETIME=[0D835580:01CC373F] Subject: Re: Tune files and knobs to turn X-BeenThere: openembedded-core@lists.openembedded.org X-Mailman-Version: 2.1.11 Precedence: list Reply-To: Patches and discussions about the oe-core layer List-Id: Patches and discussions about the oe-core layer List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 30 Jun 2011 17:08:25 -0000 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit On 06/28/2011 10:36 AM, Darren Hart wrote: > > > On 06/24/2011 04:54 AM, Koen Kooi wrote: >> Hi, >> >> We discussed tune files a bit during last nights TSC meeting and Khem had >> expressed the need before, so I'd like to get this discussion started by using >> armv7a as an example. >> >> For armv7a capable cores we have the following hardware features: >> >> * armv7a instruction set >> * thumb1 instruction set >> * thumb2 instruction set >> * VFP coprocessor >> * optional NEON coprocessor >> >> For the ABI we can choose the following: >> >> * softtp without hw support (e.g. no VFP instructions emitted, slow) >> * softfp with hw support (e.g. VFP and/or NEON instructions emitted, fast) >> * hardfp, emits VFP and/or NEON instructions, slightly faster than softfp/hw, >> incompatible with everything else >> >> And the extra knobs: >> >> * pure thumb1, no arm instructions (limited use) >> * thumb1/arm interworking >> * pure thumb2, no arm instructions >> * thumb2 interworking (not sure if that's actually usefull, thumb2 has complete coverage) >> >> In OE .dev we have the following vars: >> >> TARGET_FPU: switches between hw float and sw float, no reflection in package arch >> ARM_FP_ABI: switches between softfp and hardfp, will create 'armv7a' or >> 'armv7a-hardfp' as package arch >> ARM_INSTRUCTION_SET: switches between arm and thumb1, no reflection in package arch >> THUMB_INTERWORK: turns on interworking, no reflection in package arch >> >> (side note, oe-core/distroless and meta-yocto/poky don't turn set TARGET_FPU >> for armv7a and will generate slow code, angstrom does turn it on) > > > oe-core tune-cortexa8.inc doesn't make use of these variables (unlike > meta-texasinstruments) and does make use of the neon coprocessor, but > still uses the softfp float-api: > > TARGET_CC_ARCH = "-march=armv7-a -mtune=cortex-a8 -mfpu=neon > -mfloat-abi=softfp -fno-tree-vectorize" What's with the -fno-tree-vectorize? I had someone point out to me that the TI wiki recommends turning that on, even outside of -O3 (which enables it by default). -- Tom Rini Mentor Graphics Corporation