From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-gx0-f14.google.com (mail-gx0-f14.google.com [209.85.217.14]) by ozlabs.org (Postfix) with ESMTP id 4B57CDDEED for ; Thu, 23 Oct 2008 09:21:13 +1100 (EST) Received: by gxk7 with SMTP id 7so440429gxk.9 for ; Wed, 22 Oct 2008 15:21:10 -0700 (PDT) Message-ID: <48FFA755.5050808@genesi-usa.com> Date: Wed, 22 Oct 2008 17:21:09 -0500 From: Matt Sealey MIME-Version: 1.0 To: benh@kernel.crashing.org Subject: Re: Extended Addressing Mode References: <48FEEB88.6050505@kontron.com> <83735324-C37B-4C57-A50F-FFF0D133E4E3@kernel.crashing.org> <48FF23C4.5030408@kontron.com> <88C8EDEB-C9A5-4876-AF7D-55CBABBE111D@kernel.crashing.org> <1224713506.7654.353.camel@pasglop> In-Reply-To: <1224713506.7654.353.camel@pasglop> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: Matt Sealey Cc: linuxppc-dev@ozlabs.org, =?ISO-8859-1?Q?R=E9gis_Odey=E9?= List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Benjamin Herrenschmidt wrote: > On Wed, 2008-10-22 at 08:08 -0500, Kumar Gala wrote: >>> We are developing a board based on Freescale 8641D which can get >> 4GB >>> of ram. So I need 4GB+IOs (~1GB) of physical addressing space. >>> My plan is to put a part of this ram above of 4GB to keep accesses >>> to the IOs below the 4GB limit. It means non-contiguous ram >>> addressing and XAEN features to be working. > > Why would you put the IOs below the 4G point ? It's actually easier > to have the IOs up above, like a lot of 4xx do. Because we're Genesi! And we have a firmware solution that kind of has to keep 32-bit pointers in the unlikely event that someone actually uses the client interface (besides yaboot!). Having I/O in the 36-bit range could cause all sorts of explosions, and we're running real-mode so trapping and faking I/O accesses is REALLy difficult :} -- Matt Sealey Genesi, Manager, Developer Relations