From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: In-Reply-To: <200704121926.03723.arnd@arndb.de> References: <20070410111508.GA2969@localhost.localdomain> <200704121501.34311.arnd@arndb.de> <981B07C8-D35B-4581-8FC7-DCA58430A081@kernel.crashing.org> <200704121926.03723.arnd@arndb.de> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: From: Segher Boessenkool Subject: Re: [Cbe-oss-dev] [RFC, PATCH] selection of CPU optimization Date: Thu, 12 Apr 2007 21:50:04 +0200 To: Arnd Bergmann Cc: linuxppc-dev@ozlabs.org, cbe-oss-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , >> I think -mcpu=8540 will work for e500 (same for tune) > > Interestingly, -mcpu=8540 is known to gcc, according to > gcc-4.0.3 -dumpspecs, but is not listed in the documentation. Sure it is: gcc/gcc/config/rs6000/rs6000.c, line #s about 1250 and further ;-) It's supposed to be in the info manual too, if not, please file a PR; looks good to me though. > There is also -me500, while -me200 seems to be known only > to gas but not gcc. There is no -mcpu=e500. -me500 is a GAS option. GCC's -mcpu= options generally take specific CPU names as parameter; I suppose it would make sense to add e200 et. al. > What would be the right options to pass on e200 and on > pa6t? The best thing would be to add GCC -mcpu= options. For now, you're probably best of with -mcpu=powerpc and -mcpu=powerpc64 resp., i.e. the "blended models". This is a good option for multiplatform kernels too; add -mtune= to optimise for a specific core, but it will *work* on the whole family. Segher