Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758814AbXERB7O (ORCPT ); Thu, 17 May 2007 21:59:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756028AbXERB67 (ORCPT ); Thu, 17 May 2007 21:58:59 -0400 Received: from shawidc-mo1.cg.shawcable.net ([24.71.223.10]:63447 "EHLO pd2mo3so.prod.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755122AbXERB67 (ORCPT ); Thu, 17 May 2007 21:58:59 -0400 Date: Thu, 17 May 2007 19:58:45 -0600 From: Robert Hancock Subject: Re: [PATCH] drivers/ata: Add the SW NCQ support to sata_nv for MCP51/MCP55/MCP61 In-reply-to: To: Zoltan Boszormenyi Cc: Peer Chen , linux-kernel Message-id: <464D0855.20703@shaw.ca> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-2; format=flowed Content-transfer-encoding: 7bit References: User-Agent: Thunderbird 2.0.0.0 (Windows/20070326) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1562 Lines: 46 Zoltan Boszormenyi wrote: > Hi, > > thanks for publishing this. > >> Add the Software NCQ support to sata_nv.c for MCP51/MCP55/MCP61 SATA >> controller. >> >> This patch base on sata_nv.c file from kernel 2.6.22-rc1 >> >> See attachment for the patch. >> >> Signed-off-by: Kuan Luo >> Signed-off-by: Peer Chen >> ================================== >> See attached file. >> ================================== >> > > However, I saw this in the patch: > > + /* determine if physical DMA addr spans 64K boundary. > + * Note h/w doesn't support 64-bit, so we unconditionally > + * truncate dma_addr_t to u32. > + */ > + addr = (u32) sg_dma_address(sg); > > Does it mean that I can't upgrade my machine to 4 GB or more > without losing NCQ or risking data corruption? > Can the code be made IOMMU-aware? 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. -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/ - 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/