From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthieu CASTET Subject: Re: [PATCH 4/6] Add support for LZO-compressed kernels for ARM Date: Fri, 7 Aug 2009 13:50:03 +0200 Message-ID: <4A7C14EB.1060701@parrot.com> References: <20090731093107.GA29704@merkur.ravnborg.org> <1249311501-23102-1-git-send-email-albin.tonnerre@free-electrons.com> <1249311501-23102-2-git-send-email-albin.tonnerre@free-electrons.com> <1249311501-23102-3-git-send-email-albin.tonnerre@free-electrons.com> <1249311501-23102-4-git-send-email-albin.tonnerre@free-electrons.com> <20090806224055.GH31579@n2100.arm.linux.org.uk> <20090807092423.GA4455@laptop> <4A7BF5B8.4030907@knaff.lu> <20090807102117.GB4455@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20090807102117.GB4455@laptop> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="iso-8859-1" To: Albin Tonnerre Cc: Alain Knaff , Russell King - ARM Linux , "sam@ravnborg.org" , "hpa@zytor.com" , "linux-kernel@vger.kernel.org" , "linux-embedded@vger.kernel.org" , "akpm@linux-foundation.org" Albin Tonnerre a =E9crit : > On Fri, Aug 07, 2009 at 11:36:56AM +0200, Alain Knaff wrote : >> On 08/07/09 11:24, Albin Tonnerre wrote: >=20 >>> Regards, >=20 >> Could it be that the patches that remove division (zutil.h and infla= te.c) >> have somehow not been applied? >=20 > Indeed, they've not been applied. However, I'd rather try to understa= nd why > exactly this is an issue when compiling with -Os and not -O2 instead = of working > around it by removing the divisions. >=20 Look at the generated code. Arm doesn't have division instruction. May be at -Os gcc emit a call to the software division, but at -O2 it manage to optimise the division (transform it in shift, inline some builtin, ...). Matthieu