From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Message-ID: <17924.38058.582386.176550@cargo.ozlabs.ibm.com> Date: Sat, 24 Mar 2007 14:02:02 +1100 From: Paul Mackerras To: Segher Boessenkool Subject: Re: [PATCH] force -mno-string option on cell In-Reply-To: References: <1174544624.10836.24.camel@localhost.localdomain> <94d8e19d4b061504fcfd08d1ab70cc78@kernel.crashing.org> <20070323120619.GA7472@localhost.localdomain> Cc: Akinobu Mita , cbe-oss-dev@ozlabs.org, Arnd Bergmann , linuxppc-dev list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Segher Boessenkool writes: > What your patch does is setting -mno-string for all files > if your kernel is configured to support Cell. It would be > better to set this option (and all other options needed, > -mno-multiple and -mno-algebraic come to mind, and that last > compiler option doesn't even exist yet) unconditionally on > the few Cell-specific files that are affected, not on the > whole kernel: > > CFLAGS_whatever.o := -msome-flags Unless someone can show a measurable difference in performance between a kernel compiled with -mno-string and one compiled without (with the kernel compiled without being faster), then I would be inclined just to add -mno-string everywhere, since there are some cpus (e.g. e500 cores) where string instructions aren't implemented. Paul.