From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [patch 3/3] cell: prevent alignment interrupt on local store From: Benjamin Herrenschmidt To: Akinobu Mita In-Reply-To: <20070411025605.GB2197@localhost.localdomain> References: <20070410111508.GA2969@localhost.localdomain> <1176240168.8061.51.camel@localhost.localdomain> <20070411025605.GB2197@localhost.localdomain> Content-Type: text/plain Date: Wed, 11 Apr 2007 13:30:53 +1000 Message-Id: <1176262253.8061.60.camel@localhost.localdomain> Mime-Version: 1.0 Cc: Arnd Bergmann , linuxppc-dev@ozlabs.org, Paul Mackerras , cbe-oss-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2007-04-11 at 11:56 +0900, Akinobu Mita wrote: > On Wed, Apr 11, 2007 at 07:22:48AM +1000, Benjamin Herrenschmidt wrote: > > On Tue, 2007-04-10 at 20:15 +0900, Akinobu Mita wrote: > > > An Alignment interrupt occurs when the instruction is lmw, stmw, lswi, lswx, > > > stswi, or stswx, and the operand is in local store. > > > > > > GCC generated such instructions to handle memcpy() instead of kernel > > > defined memcpy() without -mno-string option. > > > > > > Signed-off-by: Akinobu Mita > > > > I would personally prefer building the entire kernel with -mno-string > > when cell support is enabled... > > I'm about to resend the patch which prevent alignment interrupts on LS > by using memcpy_fromio() rather than putting a collection of -mno-* options > in Makefile. (only -mno-string is not enough to prevent that as Segher said) Sure, however we also know for sure that string instructions will suck a LOT on a cell ... so for a multi platforms kernel that has cell support built-in, it makes some sense to not use them. Ben.