From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andre Renaud Subject: Re: [PATCH 1/2] ARM: Add Kconfig option to use mkimage -T kernel_noload Date: Thu, 01 Mar 2012 09:25:12 +1300 Message-ID: <4F4E89A8.4080909@bluewatersys.com> References: <1330473804-23348-1-git-send-email-swarren@nvidia.com> <20120229122942.GF3318@game.jcrosoft.org> <74CDBE0F657A3D45AFBB94109FB122FF17BDDF206A@HQMAIL01.nvidia.com> <20120229181430.GI3318@game.jcrosoft.org> <4F4E6F96.8080907@am.sony.com> <20120229191209.GN14173@pengutronix.de> <74CDBE0F657A3D45AFBB94109FB122FF17BDDF2122@HQMAIL01.nvidia.com> <20120229194409.GO14173@pengutronix.de> <74CDBE0F657A3D45AFBB94109FB122FF17BDDF2155@HQMAIL01.nvidia.com> <4F4E86A1.8010506@bluewatersys.com> <20120229201938.GB16999@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120229201938.GB16999-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Russell King - ARM Linux Cc: Stephen Warren , =?ISO-8859-1?Q?Uwe_Kleine-K=F6?= =?ISO-8859-1?Q?nig?= , Nicolas Pitre , Peter De Schrijver , Olof Johansson , Tim Bird , Colin Cross , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Jean-Christophe PLAGNIOL-VILLARD , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: linux-tegra@vger.kernel.org Hi Russell, >> I may have missed part of this, but isn't one of the points regarding >> this that the zImage decompressor always runs with data cache disabled, > > Most certainly not. We've had the data cache enabled for years and > years. And I mean 10+ years. We may have been lacking support on > some CPUs, but that was because of lack of contributions. > >> resulting in a slow decompress, where as if the U-Boot decompressor is >> used (ie, gzipping the Image, and telling U-Boot to decompress), then it >> can run with caches enabled, improving boot speed? > > That's pure FUD. I don't want to open a can of worms on this, and I certainly haven't looked into the image decompressor within the Linux kernel, but from a boot speed point of view we certainly see a significant speed improvement switching from zImage to gzipped-Image. Do you know which platforms include the data-cache support in the decompressor? Regards, Andre