Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 13 Jun 2002 11:09:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 13 Jun 2002 11:09:33 -0400 Received: from deimos.hpl.hp.com ([192.6.19.190]:27597 "EHLO deimos.hpl.hp.com") by vger.kernel.org with ESMTP id ; Thu, 13 Jun 2002 11:09:32 -0400 From: David Mosberger MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15624.46508.257287.233406@napali.hpl.hp.com> Date: Thu, 13 Jun 2002 08:09:32 -0700 To: Benjamin LaHaise Cc: linux-kernel@vger.kernel.org Subject: Re: [patch] pageattr update In-Reply-To: <20020613061246.A7121@redhat.com> X-Mailer: VM 7.03 under Emacs 21.2.1 Reply-To: davidm@hpl.hp.com X-URL: http://www.hpl.hp.com/personal/David_Mosberger/ Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Ben, I'm have a concern about the current change_page_attr() patch. It gives the impression that the GART memory always gets mapped write-combined. This is not always true. For example, on IA-64, attribute-aliasing issues are prevented by requiring IA-64 platforms to use coherent AGP DMA. In other words, the AGP memory will be mapped writeback, as usual. As long as change_page_attr() is used for AGP-related stuff only, there is probably no real issue with the patch in its current form (its simply a no-op on most non-x86 platforms). However, I'm a bit worried that someone might start to use it for other things, such that change_page_attr() could no longer be a no-op on those platforms. Since the DMA coherency issue is an AGP specific issue, perhaps just renaming the macro to agp_change_page_attr() would take care of my concern. What do you think? --david - 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/