Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965177AbVI0V4A (ORCPT ); Tue, 27 Sep 2005 17:56:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965179AbVI0V4A (ORCPT ); Tue, 27 Sep 2005 17:56:00 -0400 Received: from mail.dvmed.net ([216.237.124.58]:41692 "EHLO mail.dvmed.net") by vger.kernel.org with ESMTP id S965177AbVI0Vz7 (ORCPT ); Tue, 27 Sep 2005 17:55:59 -0400 Message-ID: <4339BFE9.1060604@pobox.com> Date: Tue, 27 Sep 2005 17:55:53 -0400 From: Jeff Garzik User-Agent: Mozilla Thunderbird 1.0.6-1.1.fc4 (X11/20050720) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Linux Kernel Mailing List , Andrew Morton , Linus Torvalds CC: Luben Tuikov , SCSI Mailing List Subject: Re: I request inclusion of SAS Transport Layer and AIC-94xx into the kernel References: <43384E28.8030207@adaptec.com> In-Reply-To: <43384E28.8030207@adaptec.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: 0.0 (/) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2061 Lines: 62 Luben Tuikov wrote: > I request inclusion of the SAS Transport Layer > and the AIC-94xx SAS LLDD into the Linux kernel. Overall, I see the following major issues. My recommendation is that this driver live in -mm, or outside the kernel tree, for a while to let things shake out. Background ---------- * There is no question that Adaptec's aic94xx and SAS code is correct WRT the SCSI specifications. The maintainer eats, sleeps, and breathes SAS specs. :) * aic94xx hardware supports both SAS and SATA connections. Since SAS and SATA are intentionally similar electrically, other vendors are coming out with SATA+SAS hardware too. * Acronym: "HCIL" Stands for Host/Channel/ID/LUN. Pre-SAS legacy addressing method. Issues ------ * Avoids existing SAS code, rather than working with it. * Avoids existing SATA code, rather than working with it. * Avoids (rather than fix) several SCSI core false dependencies on HCIL. Results in code duplication and/or avoidance of needed code. * So far, it's an Adaptec-only solution. Since it pointedly avoids the existing SAS transport code, this results in two SAS solutions in Linux: one for Adaptec, one for {everyone else}. * Maintainer reminds me of my ATA mentor, Andre Hedrick: knows his shit, but has difficulties working with the community. May need a filter if we want long term maintenance to continue. Resolution ---------- AFAICS, there are two paths: Easy path: make Adaptec's solution a block driver, which allows it to sidestep all the "doesn't play well with others" issues. Still an Adaptec-only solution, but at least its in a separate playpen. Hard path: Update the SCSI core and libata to work with SATA+SAS hardware such as Adaptec's. The hard path takes time, and won't be solved simply by shoving it in. 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/