From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Pitre Subject: Re: Where to put a large bootloader-supplied device tree on ARM ? Date: Thu, 12 Jul 2012 14:16:01 -0400 (EDT) Message-ID: References: <1341325365-21393-1-git-send-email-andrew@lunn.ch> <201207051454.24475.arnd@arndb.de> <20120705161600.GA28860@lunn.ch> <201207062008.23952.arnd@arndb.de> <20120706210009.GC11470@lunn.ch> <4FF781D8.3040206@firmworks.com> <2966DB01BC317A4DA23684BA0F653415013701@xmb-aln-x08.cisco.com> <4FF7980E.7050705@firmworks.com> <4FFE743B.6080504@firmworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <4FFE743B.6080504-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Mitch Bradley Cc: "devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org On Wed, 11 Jul 2012, Mitch Bradley wrote: > On 7/8/2012 6:30 PM, Nicolas Pitre wrote: > > On Fri, 6 Jul 2012, Mitch Bradley wrote: > > > >> For now, I'm putting the initrd at the end of memory and the dtb > >> below that. That seems to work, but I'm unsure whether or not > >> I'm just "getting lucky". > > > > That's also perfectly fine. > > Alas, that worked for machines with 512 MiB of main memory, but failed > on 1 GiB machines. My guess is that, when the initrd and dtb are near > the top of a 1 GiB memory, the virtual address gets too near the top of > the kernel's 1 GiB of virtual space (which starts at 0xc0000000), > perhaps colliding with the VMALLOC space. Indeed, that won't work in that case. > Putting them just below the 128 MiB boundary seems to work. Or at the 128MB mark, or any location between 64MB and 512MB should be fine in practice. Nicolas