From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: Query regarding modifying the DMA Mask based on the available memory in the system Date: Thu, 17 Apr 2008 18:10:54 +0200 Message-ID: <4807768E.20302@firstfloor.org> References: <5AE055B67BB5764693E2900C7E3699BE010CAB76@pamail.ad.lsil.com> <1208441932.3150.4.camel@localhost.localdomain> <87iqygk0bu.fsf@basil.nowhere.org> <1208444622.3150.10.camel@localhost.localdomain> <4807678A.8020906@firstfloor.org> <1208446607.3150.16.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from one.firstfloor.org ([213.235.205.2]:35355 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763161AbYDQQLG (ORCPT ); Thu, 17 Apr 2008 12:11:06 -0400 In-Reply-To: <1208446607.3150.16.camel@localhost.localdomain> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: "Prakash, Sathya" , linux-scsi@vger.kernel.org James Bottomley wrote: > On Thu, 2008-04-17 at 17:06 +0200, Andi Kleen wrote: >> James Bottomley wrote: >>> On Thu, 2008-04-17 at 16:44 +0200, Andi Kleen wrote: >>>>> For drivers that can alter their descriptor types, we have this >>>>> function: >>>>> >>>>> dma_get_required_mask() >>>> Are you sure we have it? It seems to be in drivers/base/platform.c >>>> conditional on ARCH_HAS_DMA_GET_REQUIRED_MASK, but according to my >>>> grep no architecture ever sets that flag. >>> Yes ... positive. That's the default and correct implementation based >>> on the largest addressable physical memory. >> Ok but still the whole thing is completely useless right now. > > Why? At least for aic it performs as advertised: allows the driver to > select the most efficient descriptor format. You were right sorry, I misread the code. Your interpretation is correct. The interface would be correct to use for fusion, although it should be probably extended to IOMMUs too. -Andi