Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760062AbXEROez (ORCPT ); Fri, 18 May 2007 10:34:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755382AbXEROes (ORCPT ); Fri, 18 May 2007 10:34:48 -0400 Received: from srv5.dvmed.net ([207.36.208.214]:49101 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755321AbXEROer (ORCPT ); Fri, 18 May 2007 10:34:47 -0400 Message-ID: <464DB97B.8030204@garzik.org> Date: Fri, 18 May 2007 10:34:35 -0400 From: Jeff Garzik User-Agent: Thunderbird 1.5.0.10 (X11/20070302) MIME-Version: 1.0 To: Alan Cox CC: Robert Hancock , Zoltan Boszormenyi , Peer Chen , linux-kernel Subject: Re: [PATCH] drivers/ata: Add the SW NCQ support to sata_nv for MCP51/MCP55/MCP61 References: <464D0855.20703@shaw.ca> <20070518133456.5f1392e9@the-village.bc.nu> In-Reply-To: <20070518133456.5f1392e9@the-village.bc.nu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.3 (----) X-Spam-Report: SpamAssassin version 3.1.8 on srv5.dvmed.net summary: Content analysis details: (-4.3 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 822 Lines: 23 Alan Cox wrote: >> That shouldn't be a problem, libata default DMA mask is 32 bits (which >> isn't overridden with this controller) and so the block layer will >> bounce any data being read/written above that point with IOMMU or >> swiotlb. The comment is a bit unnecessarily scary. > > Adding a BUG_ON for this would be wise. Its trivial to check and a BUG > rather than corruption if this assumption ever changes would be far > preferable The default DMA mask -everywhere- is 32 bits. A lot of code will break if this assumption ever changes, not just libata. Jeff - 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/