From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: libata+SGIO: is .dma_boundary respected? Date: Tue, 21 Mar 2006 01:14:04 -0500 Message-ID: <441F99AC.4000200@pobox.com> References: <441DC397.9040504@rtr.ca> <441DC9CB.7030203@pobox.com> <441DCAC9.5090603@rtr.ca> <441DCF73.2080600@pobox.com> <441DD101.5050202@rtr.ca> <441DD300.9050702@rtr.ca> <441F544A.6080301@pobox.com> <441F8478.50806@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:12779 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S1030348AbWCUGOI (ORCPT ); Tue, 21 Mar 2006 01:14:08 -0500 In-Reply-To: <441F8478.50806@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: Jens Axboe , IDE/ATA development list Mark Lord wrote: > But (as I replied to myself earlier), I think it is a non issue, > because the IOMMU merging cannot produce more SG entries than > there were originally. It may produce less, and the driver may then > end up splitting them apart again, but it will never exceed what > the block layer permitted in the first place. That says nothing about the boundaries upon which the IOMMU layer will or will not merge. Without the fix, the problem case happens when (for example) the IOMMU output produces sg_tablesize segments, but some of those segments cross a 64k boundary and need to be split. Jeff