From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752338AbbIQFNb (ORCPT ); Thu, 17 Sep 2015 01:13:31 -0400 Received: from ozlabs.org ([103.22.144.67]:38596 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751260AbbIQFNa (ORCPT ); Thu, 17 Sep 2015 01:13:30 -0400 X-powerpc-patch-notification: thanks X-powerpc-patch-commit: 1cd03890ea64795e53f17a94928cca22495acb2a In-Reply-To: To: LEROY Christophe , Benjamin Herrenschmidt , Paul Mackerras , scottwood@freescale.com, sojkam1@fel.cvut.cz From: Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [v4,1/2] powerpc32: memcpy: only use dcbz once cache is enabled Message-Id: <20150917051327.C91901401EF@ozlabs.org> Date: Thu, 17 Sep 2015 15:13:27 +1000 (AEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2015-16-09 at 10:04:51 UTC, LEROY Christophe wrote: > memcpy() uses instruction dcbz to speed up copy by not wasting time > loading cache line with data that will be overwritten. > Some platform like mpc52xx do no have cache active at startup and > can therefore not use memcpy(). Allthough no part of the code > explicitly uses memcpy(), GCC makes calls to it. > > This patch modifies memcpy() such that at startup, memcpy() > unconditionally jumps to generic_memcpy() which doesn't use > the dcbz instruction. > > Once the initial MMU is set up, in machine_init() we patch memcpy() > by replacing this inconditional jump by a NOP > > Reported-by: Michal Sojka > Signed-off-by: Christophe Leroy Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/1cd03890ea64795e53f17a94 cheers