From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: RFC: ARM Boot standard for passing device tree blob Date: Fri, 26 Mar 2010 23:00:59 +0000 Message-ID: <20100326230059.GB29179@n2100.arm.linux.org.uk> References: <20100325210409.GH24984@n2100.arm.linux.org.uk> <1269610665.807.51.camel@e102109-lin.cambridge.arm.com> <4BACF238.3040405@firmworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <4BACF238.3040405-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Mitch Bradley Cc: Catalin Marinas , devicetree-discuss , Philippe Robin , David Rusling , Jeremy Kerr , Dave P Martin , linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On Fri, Mar 26, 2010 at 07:43:20AM -1000, Mitch Bradley wrote: > What is the reason for turning off the data caches? Leaving all caches > turned on and coherent with one another has always worked well for me at > the interface from firmware to a booted program. With the data caches on, you need the MMU to be setup and operational. That's impractical when you're passing control between differing pieces of software which may have different ideas about how to setup the MMU and where to place the page tables. If you accidentally overwrite the page tables, things quickly become undebuggable.