From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by yocto-www.yoctoproject.org (Postfix, from userid 118) id B13AFE00C4A; Thu, 12 Nov 2015 09:04:00 -0800 (PST) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on yocto-www.yoctoproject.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 X-Spam-HAM-Report: * -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, * medium trust * [147.11.1.11 listed in list.dnswl.org] Received: from mail.windriver.com (mail.windriver.com [147.11.1.11]) by yocto-www.yoctoproject.org (Postfix) with ESMTP id 81089E00C3B for ; Thu, 12 Nov 2015 09:03:57 -0800 (PST) Received: from ALA-HCA.corp.ad.wrs.com (ala-hca.corp.ad.wrs.com [147.11.189.40]) by mail.windriver.com (8.15.2/8.15.1) with ESMTPS id tACH3gPA018942 (version=TLSv1 cipher=AES128-SHA bits=128 verify=FAIL); Thu, 12 Nov 2015 09:03:43 -0800 (PST) Received: from Marks-MacBook-Pro.local (172.25.36.226) by ALA-HCA.corp.ad.wrs.com (147.11.189.50) with Microsoft SMTP Server id 14.3.248.2; Thu, 12 Nov 2015 09:03:42 -0800 To: Toby Gomersall , References: <5644591F.1090703@smartacoustics.co.uk> From: Mark Hatle X-Enigmail-Draft-Status: N1110 Organization: Wind River Systems Message-ID: <5644C66D.4030408@windriver.com> Date: Thu, 12 Nov 2015 11:03:41 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <5644591F.1090703@smartacoustics.co.uk> Subject: Re: Building yocto with hard float support X-BeenThere: yocto@yoctoproject.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Discussion of all things Yocto Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Nov 2015 17:04:00 -0000 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit On 11/12/15 3:17 AM, Toby Gomersall wrote: > Hi, > > I want to build yocto with hard float support. I understand that I can > point the EXTERNAL_TOOLCHAIN variable at the appropriate external hard > float compiler (gcc-5-arm-linux-gnueabihf). However, I was wondering if > there was anything within the yocto project to do this? I'm going to be pedantic for a second.. bear with me. ARM has two ABIs, the standard EABI which passes floating point values via integer registers and EABIHF that passes floating point values via floating point registers. EABI allows hardware floating point along with neon or any other core specific optimizations. EABIHF requires a specific set and size of VFP registers. The Yocto Project is capable of building for both ABIs with whatever combinations of optimizations you need. The ABI and default processor optimization is configured by the 'DEFAULTTUNE' parameter. This is typically defined in your machine configuration file, either explicitly or implicitly via the including of the tune files. So for example, if you have an ARMv5 CPU you would likely use: DEFAULTTUNE="armv5e" This would select ARM EABI, no VFP. alternatively you could do: DEFAULTTUNE="armv5e-vfp" This would select ARM EABI w/ VFP floating point. OR (what I think you are actually trying to ask) DEFAULTTUNE="armv5ehf-vfp" This would select ARM EABIHF w/ VFP floating point. So start with your machine and determine which defaulttune (bitbake -e) you have selected. Adjust it to a compatible setting for the ABI and processor optimizations that you wish to use. > I'm concerned that future updates to an external compiler might affect > my build and I would prefer to use a method from within the yocto project. Unless you have a specific need, I don't recommend external compilers. The Yocto Project compilers and configurations are well tested and high quality. While using an external compiler is support by some vendors, it adds complexity that may not be beneficial. (Sometimes support and other aspects of commercial offerings outweigh the complexity..) > Thank you, > Toby > > >