From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-out.m-online.net (mail-out.m-online.net [212.18.0.9]) by ozlabs.org (Postfix) with ESMTP id 8FEC767B90 for ; Sat, 11 Feb 2006 12:20:29 +1100 (EST) To: atul.sabharwal@exgate.tek.com From: Wolfgang Denk Subject: Re: kernel startup Mime-version: 1.0 Content-type: text/plain; charset=ISO-8859-1 In-reply-to: Your message of "Fri, 10 Feb 2006 16:28:28 PST." <4A062D477D842B4C8FC48EA5AF2D41F201BA2089@us-bv-m23.global.tektronix.net> Date: Sat, 11 Feb 2006 02:20:27 +0100 Sender: wd@denx.de Message-Id: <20060211012027.DD9C8353B42@atlas.denx.de> Cc: linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , In message <4A062D477D842B4C8FC48EA5AF2D41F201BA2089@us-bv-m23.global.tektronix.net> you wrote: > > Not much choice with IMMR as it can be 0x0 or 0x00f00000 or 0xFF000000 > Or 0xFFF00000. Initially. But you can change it. > Flash is from 0xfe000000 thru 0xffffffff. Now on POR, > Processor goes to offset 0x100 on CS0. So, if IMMR is overlapping with > flash, it might not boot. Just fix your memory map. > On 870, it seems that reset value for BR0/OR0 is undefined. Please RTFM. The steps how the processor comes up from reset are documented in great detail. Especially the handling of the boot device chip select. > Data fetch goes on CS0 and then in cpu_init_f BR0 & OR0 > Are remapped. So, I could put flash at a non-standard address like > 0xDE000000 and move IMMR to 0xFF000000. There is no such thing as a "non-standard" address, as there is no "standard" address either. > The problem this creates is that I can set IIP to 0 or 1. So, exception > Vector prefix can be 0 or 0xfff. Since no flash at 0xfff00000 base > Address I cannot have any exceptions in my code till the u-boot code > has relocated to RAM. Which should be acceptable as what can I do > if there is exception so early in the system. In most cases it is useful to configure a system for low-boot, i. e. let it start at 0x0100. Then just set up your memory map as you like... Best regards, Wolfgang Denk -- Software Engineering: Embedded and Realtime Systems, Embedded Linux Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de You don't need a weatherman to know which way the wind blows. - Bob Dylan