From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757519Ab3KMQOq (ORCPT ); Wed, 13 Nov 2013 11:14:46 -0500 Received: from mail-ob0-f171.google.com ([209.85.214.171]:33333 "EHLO mail-ob0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753533Ab3KMQOo (ORCPT ); Wed, 13 Nov 2013 11:14:44 -0500 Message-ID: <5283A573.6020403@gmail.com> Date: Wed, 13 Nov 2013 10:14:43 -0600 From: Rob Herring User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: monstr@monstr.eu, Geert Uytterhoeven CC: Andrew Morton , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Rob Herring , microblaze-uclinux@itee.uq.edu.au, devicetree@vger.kernel.org Subject: Re: [PATCH RFC 15/17] microblaze: Convert from _fdt_start to __dtb_start References: <1384285347-13506-1-git-send-email-geert@linux-m68k.org> <1384285347-13506-16-git-send-email-geert@linux-m68k.org> <5283524F.8030902@monstr.eu> <5283814C.6040904@monstr.eu> In-Reply-To: <5283814C.6040904@monstr.eu> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/13/2013 07:40 AM, Michal Simek wrote: > On 11/13/2013 11:19 AM, Michal Simek wrote: >> On 11/12/2013 08:42 PM, Geert Uytterhoeven wrote: >>> Kill the microblaze-specific __fdt_blob section, and start >>> using .dtb.init.rodata from for >>> built-in DTBs, like most other DT enabled architectures. >>> >>> Signed-off-by: Geert Uytterhoeven Cc: >>> Michal Simek Cc: Rob Herring >>> Cc: >>> microblaze-uclinux@itee.uq.edu.au Cc: >>> devicetree@vger.kernel.org --- Untested, but the resulting >>> vmlinux after "make simpleImage.system" looks sane. >>> >>> QUESTION: The padding of the DTB is gone, is this OK? >> >> Removing this kernel padding should be fine. I can't remember why >> it was there from the beginning. > > I know why is this here. The reason is process how dtb is passed to > the kernel via command line. head.S code just copy that dtb to the > same location where compiled-in dts is expected and kernel doesn't > need to care about position of dtb because this copy is done > without MMU. And the full kernel is covered by 2 tlbs and we don't > need to use another TLB for dtb mapping. > > It means pad matters a lot. Because u-boot ITS format doesn't use > simpleImage target but the kernel need to have a space for copying > dtb to this kernel location. > > Let me think about if there is an easy way to handle dtbs which are > passed from bootloader. Isn't the built-in dtb in a RO init section? Seems like a bad idea to write to it. Also, it will be a double copy because a built-in dtb has to be copied out of init section. Rob