From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay1.mentorg.com (relay1.mentorg.com [192.94.38.131]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "relay1.mentorg.com", Issuer "Entrust Certification Authority - L1B" (not verified)) by ozlabs.org (Postfix) with ESMTPS id A99ECB70E2 for ; Thu, 17 Feb 2011 07:02:59 +1100 (EST) Message-ID: <4D5C2D6C.8000906@mentor.com> Date: Wed, 16 Feb 2011 14:02:52 -0600 From: Meador Inge MIME-Version: 1.0 To: Scott Wood Subject: Re: Using CONFIG_PHYSICAL_START References: <4D5C10B9.9010702@mentor.com> <20110216132403.3466a83e@schlenkerla> In-Reply-To: <20110216132403.3466a83e@schlenkerla> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: "linuxppc-dev@lists.ozlabs.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 02/16/2011 01:24 PM, Scott Wood wrote: > On Wed, 16 Feb 2011 12:00:25 -0600 > Meador Inge wrote: > >> Hi Kumar, >> >> Quick question about the support for booting at a non-zero base address >> (as committed here: >> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=37dd2badcfcec35f5e21a0926968d77a404f03c3). >> Is booting from a non-zero address as simple as changing >> "CONFIG_PHYSICAL_START" (assuming it meets the alignment constraints, of >> course)? > > Another option is to turn on CONFIG_RELOCATABLE. Note that you'll still > have the same alignment constraints; it doesn't generate a truly relocatable > binary (the effective addresses are fixed). But you don't have to specify > the physical address at compile-time. This allows you to use the same > kernel image for multiple AMP partitions. > >> For example, I want to boot from a non-zero address on the P1022DS. I >> should just be able to change "CONFIG_PHYSICAL_START" to, say, >> 0x08000000, and it should work, right? Any other bits that need to be >> done (i.e. U-Boot or device tree magic)? > > You'll want the memory node adjusted for your restricted address range > (I'm assuming that this is why you want to start at non-zero, and that > you're not trying to have the kernel be located in the middle of its > partition). > > There are some special u-boot variables (bootm_low/bootm_size) that govern > placement of the kernel, fdt, etc. Thanks Scott. I should have looked in the u-boot docs. There are very clear instructions on how to setup an AMP environment in '.../doc/README.mpc8572ds' (http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=blob;f=doc/README.mpc8572ds;h=06dab596bea52ab8d8c2ba89d86f793cc4881ccb;hb=HEAD). > -Scott > > -- Meador Inge | meador_inge AT mentor.com Mentor Embedded | http://www.mentor.com/embedded-software