From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751286Ab0DGTa0 (ORCPT ); Wed, 7 Apr 2010 15:30:26 -0400 Received: from acsinet12.oracle.com ([141.146.126.234]:21710 "EHLO acsinet12.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750743Ab0DGTaZ (ORCPT >); Wed, 7 Apr 2010 15:30:25 -0400 Date: Wed, 7 Apr 2010 15:28:21 -0400 From: Konrad Rzeszutek Wilk To: FUJITA Tomonori Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, albert_herranz@yahoo.es, chrisw@sous-sol.org, Ian.Campbell@eu.citrix.com, jeremy@goop.org, dwmw2@infradead.org, alex.williamson@hp.com Subject: Re: [LKML] Re: [PATCH] swiotlb v0.6: seperation of physical/virtual address translation Message-ID: <20100407192821.GB5040@phenom.dumpdata.com> References: <1269011062-25915-1-git-send-email-konrad.wilk@oracle.com> <20100405110317R.fujita.tomonori@lab.ntt.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100405110317R.fujita.tomonori@lab.ntt.co.jp> User-Agent: Mutt/1.5.19 (2009-01-05) X-Source-IP: acsmt354.oracle.com [141.146.40.154] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A0B0203.4BBCDD11.00A2:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > Since the last posting I've: > > - Made the exported functions/variables have the 'swiotlb_bk' prefix instead > > of the 'do_[map|unmap]*' and 'io_tlb_*' combination. > > Why can't we use more simpler names such as 'swiotlb_tbl_index'? Much better. I was trying to come up with a name and the one I came up with was 'bookkeeping', which I shortned to 'bk'. But 'tbl' sounds better. > Why do we need to add the prefix to static things like > 'swiotlb_bk_list', 'swiotlb_bk_index', etc? Please let them alone. Yup. Removed. > > I had not addressed the question of removing the 'overflow' buffer. There are over > > ~300 instances of the the DMA operations not being checked which plan on addressing > > in a seperate set of patches that will slowly roll out the checks and then > > finally the removal of the 'overflow' buffer. > > Except for swiotlb, no IOMMU implementations has the mechanism of I believe the GART one does it too. I think the overflow points to the first page of the GART address and has logic to remind the user that danger is immenient. > overflow buffer. So drivers that don't check a DMA mapping error are > broken anyway. Also the size of the overflow is 32K by default. We > often see larger request than that. Even with the overflow mechanism, > we see data corruption anyway.