From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Gibson Subject: Re: [sodaville] [RFC] [PATCH V2] Adding DTB to architecture independent vmlinux Date: Fri, 29 Oct 2010 15:02:54 +1100 Message-ID: <20101029040254.GA5250@yookeroo> References: <4CC6E491.7060304@gmail.com> <20101027110937.GD7822@angua.secretlab.ca> <4CC860EF.6060503@linux.intel.com> <4CC8C423.9050600@gmail.com> <20101028005754.GA27386@dvomlehn-lnx2.corp.sa.net> <4CC99441.4030307@linux.intel.com> <4CC9A66B.6070408@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <4CC9A66B.6070408-hfZtesqFncYOwBW4kG4KsQ@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: Sebastian Andrzej Siewior Cc: sodaville-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org, devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, "H. Peter Anvin" List-Id: devicetree@vger.kernel.org On Thu, Oct 28, 2010 at 06:35:55PM +0200, Sebastian Andrzej Siewior wrote: > H. Peter Anvin wrote: > >How big are these blobs in the typical case? Padding to the page > >size > You usually pad the dtb by 1kib (-p 1024 in dtc). Converting all dtbs in > powerpc's tree leads to: > 991545 / 130 = 7627 bytes average. If you're folding a whole batch of dtbs into the kernel, doing the 1kib padding on each is probably not sensible. The padding is so that tweaks to the dtb which require expansion can be done easily, but if you're relocating the dtb anyway, you can allocate more space at that time, with fdt_open_into(). That would bring the average size down to 6603 bytes (-p 1024 is "1024 bytes of extra space", not "expand to a 1024 byte boundary"). -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson