From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752946Ab0I2LH3 (ORCPT ); Wed, 29 Sep 2010 07:07:29 -0400 Received: from mail.southpole.se ([193.12.106.18]:52665 "EHLO mail.southpole.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752323Ab0I2LH2 (ORCPT ); Wed, 29 Sep 2010 07:07:28 -0400 Subject: Re: ioremap definition in generic io.h From: Jonas Bonn To: Jiri Slaby Cc: linux-kernel@vger.kernel.org In-Reply-To: <4CA31AA6.7020003@gmail.com> References: <1285747145.12259.3.camel@needafix> <4CA31AA6.7020003@gmail.com> Content-Type: text/plain; charset="UTF-8" Organization: South Pole AB Date: Wed, 29 Sep 2010 13:07:26 +0200 Message-ID: <1285758446.12259.9.camel@needafix> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-09-29 at 12:53 +0200, Jiri Slaby wrote: > On 09/29/2010 09:59 AM, Jonas Bonn wrote: > > I'm wondering about the usefulness of the definition of ioremap and > > __ioremap in asm-generic/io.h. How is this intended to be used? How > > are the page tables for this mapping supposed to be constructed? > > Which page tables? The functions there are for machines w/o MMU with 1:1 > phys:virt mapping. > OK, thanks. It's not clear from asm-generic/io.h that it's intended for NOMMU systems only. Aside from the ioremap definition, everything in that file should be applicable generically... or am I missing something? On another note, looking at the definitions of ioread32/iowrite32, they imply a little-endian bus. Some architectures (e.g. Microblaze) define these to use host-native byte ordering instead. Is there a _correct_ way these functions should be defined? /Jonas