From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756434Ab2GJQzO (ORCPT ); Tue, 10 Jul 2012 12:55:14 -0400 Received: from g6t0186.atlanta.hp.com ([15.193.32.63]:3319 "EHLO g6t0186.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754089Ab2GJQzM (ORCPT ); Tue, 10 Jul 2012 12:55:12 -0400 Message-ID: <1341939307.2502.34.camel@lorien2> Subject: Re: [PATCH RFC] swiotlb: Remove SWIOTLB overflow buffer support From: Shuah Khan Reply-To: shuah.khan@hp.com To: Konrad Rzeszutek Wilk Cc: fujita.tomonori@lab.ntt.co.jp, LKML , akpm@linux-foundation.org, paul.gortmaker@windriver.com, bhelgaas@google.com, amwang@redhat.com, shuahkhan@gmail.com Date: Tue, 10 Jul 2012 10:55:07 -0600 In-Reply-To: <20120709202505.GA9541@phenom.dumpdata.com> References: <1341615972.3101.27.camel@lorien2> <20120709202505.GA9541@phenom.dumpdata.com> Organization: ISS-Linux Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2012-07-09 at 16:25 -0400, Konrad Rzeszutek Wilk wrote: > On Fri, Jul 06, 2012 at 05:06:12PM -0600, Shuah Khan wrote: > > Remove SWIOTLB overflow buffer support and return DMA_ERROR_CODE > > (a value of zero) to make it consistent with iommu implementation > > on Intel, AMD, and swiotlb-xen. > > While this is a good forward step and this needs to be done eventually, > you should first send out patches for the drivers that don't check > for the DMA_ERROR_CODE when doing mapping. In other words for the > drivers that map but don't call dma_mapping_error to check. > > When that is fixed and *all the drivers that don't call dma_mapping_error > are fixed, then this patch makes sense. The challenge will be catching all the drivers and have confidence that all of them are covered. I will start looking into this to get a feel for how many drivers needs fixing. Also, isn't this problem today with other iommu implementations? All of the other iommu implementation don't have support for overflow buffers? -- Shuah