From owner-freebsd-current@FreeBSD.ORG Thu Nov 11 10:05:40 2010 Return-Path: Delivered-To: freebsd-current@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 72C521065672 for ; Thu, 11 Nov 2010 10:05:40 +0000 (UTC) (envelope-from joerg.schilling9ab33xy531fokus.fraunhofer.de@bounce.antispameurope.com) Received: from relay03-haj2.antispameurope.com (relay03-haj2.antispameurope.com [83.246.65.53]) by mx1.freebsd.org (Postfix) with ESMTP id 016438FC0A for ; Thu, 11 Nov 2010 10:05:39 +0000 (UTC) Received: by relay03-haj2.antispameurope.com (ASE-Secure-MTA, from userid 1000) id E3E247D4013; Thu, 11 Nov 2010 11:05:37 +0100 (CET) Received: from pluto.fokus.fraunhofer.de (pluto.fokus.fraunhofer.de [195.37.77.164]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by relay03-haj2.antispameurope.com (ASE-Secure-MTA) with ESMTP id 34ED063C239; Thu, 11 Nov 2010 11:05:36 +0100 (CET) Received: from EXCHSRV.fokus.fraunhofer.de (bohr.fokus.fraunhofer.de [10.147.9.231]) by pluto.fokus.fraunhofer.de (8.14.2/8.14.2) with SMTP id oABA5ZAW000889; Thu, 11 Nov 2010 11:05:35 +0100 (MET) Received: from rigel ([10.147.65.195]) by EXCHSRV.fokus.fraunhofer.de with Microsoft SMTPSVC(6.0.3790.3959); Thu, 11 Nov 2010 11:05:36 +0100 Date: Thu, 11 Nov 2010 11:05:35 +0100 From: Joerg.Schilling@fokus.fraunhofer.de (Joerg Schilling) To: mav@FreeBSD.org Message-ID: <4cdbbfef.v4cr/k2jZr9gdpyF%Joerg.Schilling@fokus.fraunhofer.de> References: <4CD45209.5010607@FreeBSD.org> <20101105192028.GA68728@alchemy.franken.de> <4cd822df.o/wBtwsNCXiy8xZn%Joerg.Schilling@fokus.fraunhofer.de> <4CD82E2A.3070407@FreeBSD.org> <4cd8320a.U7/OjtLLBVtE4dTy%Joerg.Schilling@fokus.fraunhofer.de> <4CD83535.1010008@FreeBSD.org> In-Reply-To: <4CD83535.1010008@FreeBSD.org> User-Agent: nail 11.22 3/20/05 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-OriginalArrivalTime: 11 Nov 2010 10:05:36.0084 (UTC) FILETIME=[FC21E940:01CB8187] X-Mailman-Approved-At: Thu, 11 Nov 2010 11:58:48 +0000 Cc: freebsd-scsi@FreeBSD.org, freebsd-current@FreeBSD.org, freebsd-stable@FreeBSD.org, marius@alchemy.franken.de Subject: Re: Sense fetching [Was: cdrtools /devel ...] X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Nov 2010 10:05:40 -0000 Alexander Motin wrote: > >>> Given the fact that many drives will probably only return 18 bytes of sense > >>> data, this will happen every time libscg is told to fetch more sense than the > >>> drive is willing to return. > >>> > >>> Is there a way to distinct an old kernel from a new one? > >> I don't see the problem. Previous kernel in most cases reported > >> sesnse_resid == 0, lying that there is more sense data then really is. > >> New one should report real (often positive) value. In both cases > >> sesnse_resid value measured from the value submitted to the kernel. > > > > Did the old kernel return a zero sense_resid for any implemented SCSI > > transport? Libscg is a generic SCSI transport library and cdrecord is just one > > user of this lib. > > Not sure I understand your question. Zero sesnse_resid is absolutely > normal situation if device gave same amount of sense as application > requested. As I can see, many of SCSI controllers report sesnse_resid > properly. I may assume that some, like atapicd don't -- in that case > you'll also see 0 there. FreeBSD-CAM did try to fetcth more than 18 bytes of sense data and it may be that some drives did return only 18 bytes. In this case, I would asume that there is a resid > 0. > > Do you know the CAM behavior for other SCSI transports? > > I don't have real SCSI CD to test, but a as I can see, most of SCSI > controllers return sense data automatically. Sense fetching changes > should not affect/break anything there. The question still remains whether the previous implementation did return resid > 0 in some cases. In this case, I would need to implement both variants in the libscg adaption layer and I would need to know whether I am running on an old version or on a new version kernel. Do you know of a simple method to implement this distinction? Jörg -- EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin js@cs.tu-berlin.de (uni) joerg.schilling@fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/ URL: http://cdrecord.berlios.de/private/ ftp://ftp.berlios.de/pub/schily