From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga11.intel.com ([192.55.52.93]) by linuxtogo.org with esmtp (Exim 4.72) (envelope-from ) id 1QbcHA-0004nX-0h for openembedded-core@lists.openembedded.org; Tue, 28 Jun 2011 19:40:40 +0200 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga102.fm.intel.com with ESMTP; 28 Jun 2011 10:36:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.65,437,1304319600"; d="scan'208";a="23910103" Received: from unknown (HELO [10.255.13.106]) ([10.255.13.106]) by fmsmga001.fm.intel.com with ESMTP; 28 Jun 2011 10:36:56 -0700 Message-ID: <4E0A1136.7030402@linux.intel.com> Date: Tue, 28 Jun 2011 10:36:54 -0700 From: Darren Hart User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110424 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: Patches and discussions about the oe-core layer References: In-Reply-To: Cc: Koen Kooi 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: Tue, 28 Jun 2011 17:40:40 -0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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" Seems like the oe-core tune files need to be synced up with vendor layers? -- Darren > > Khem and I would like to start building armv7a (and armv6) in pure thumb2 mode > but we want to have the variables to turn those knobs make sense and be > consistent. RP has expressed his desire to sort this all out before merging > multilib. I'm sure x86/mips/ppc/etc have a similar need, so let's get this > discussion started. > > regards, > > Koen > _______________________________________________ > Openembedded-core mailing list > Openembedded-core@lists.openembedded.org > http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core -- Darren Hart Intel Open Source Technology Center Yocto Project - Linux Kernel