Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760705AbXIRWWy (ORCPT ); Tue, 18 Sep 2007 18:22:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754600AbXIRWWq (ORCPT ); Tue, 18 Sep 2007 18:22:46 -0400 Received: from gate.crashing.org ([63.228.1.57]:33227 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754265AbXIRWWp (ORCPT ); Tue, 18 Sep 2007 18:22:45 -0400 Subject: Re: [PATCH] Clarify pci_iomap() usage for MMIO-only devices From: Benjamin Herrenschmidt To: Linus Torvalds Cc: "Luis R. Rodriguez" , Alan Cox , linux-kernel , Jeff Garzik , "John W. Linville" , linux-wireless In-Reply-To: References: <43e72e890709171322x76ab6b70xd29bf97e3643c553@mail.gmail.com> <20070918113401.6a8a737f@the-village.bc.nu> <43e72e890709181146s604e0f9fl8b0c16627469c77f@mail.gmail.com> <43e72e890709181207j7c85dc29sb355a9f5a4207411@mail.gmail.com> <43e72e890709181312sf2b421cn49be3389b3786a2a@mail.gmail.com> Content-Type: text/plain Date: Wed, 19 Sep 2007 08:21:57 +1000 Message-Id: <1190154117.6403.127.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 743 Lines: 20 On Tue, 2007-09-18 at 13:30 -0700, Linus Torvalds wrote: > Quite frankly, if performance is a _real_ reason to avoid > ioread*/iowrite*, I'll happily accept read*/write*, but it would be > needed > to be backed up by real numbers. Can you even measure it? > Also, I've been told that modern x86 chipsets have the ability to remap IO space in the CPU physical address space. Is that true ? That would allow even x86 to get rid of the condition and just use some magic offset at map time. Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/