From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932082AbWBMKmI (ORCPT ); Mon, 13 Feb 2006 05:42:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932076AbWBMKmI (ORCPT ); Mon, 13 Feb 2006 05:42:08 -0500 Received: from mailhub.fokus.fraunhofer.de ([193.174.154.14]:34471 "EHLO mailhub.fokus.fraunhofer.de") by vger.kernel.org with ESMTP id S932082AbWBMKmH (ORCPT ); Mon, 13 Feb 2006 05:42:07 -0500 From: Joerg Schilling Date: Mon, 13 Feb 2006 11:40:32 +0100 To: schilling@fokus.fraunhofer.de, jerome.lacoste@gmail.com Cc: peter.read@gmail.com, mj@ucw.cz, matthias.andree@gmx.de, linux-kernel@vger.kernel.org, jim@why.dont.jablowme.net, jengelh@linux01.gwdg.de, dhazelton@enter.net Subject: Re: CD writing in future Linux (stirring up a hornets' nest) Message-ID: <43F06220.nailKUS5D8SL2@burner> References: <20060208162828.GA17534@voodoo> <20060210114721.GB20093@merlin.emma.line.org> <43EC887B.nailISDGC9CP5@burner> <200602090757.13767.dhazelton@enter.net> <43EC8F22.nailISDL17DJF@burner> <5a2cf1f60602100738r465dd996m2ddc8ef18bf1b716@mail.gmail.com> In-Reply-To: <5a2cf1f60602100738r465dd996m2ddc8ef18bf1b716@mail.gmail.com> User-Agent: nail 11.2 8/15/04 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org jerome lacoste wrote: > On 2/10/06, Joerg Schilling wrote: > > "D. Hazelton" wrote: > > > > > And does cdrecord even need libscg anymore? From having actually gone through > > > your code, Joerg, I can tell you that it does serve a larger purpose. But at > > > this point I have to ask - besides cdrecord and a few other _COMPACT_ _DISC_ > > > writing programs, does _ANYONE_ use libscg? Is it ever used to access any > > > other devices that are either SCSI or use a SCSI command protocol (like > > > ATAPI)? My point there is that you have a wonderful library, but despite > > > your wishes, there is no proof that it is ever used for anything except > > > writing/ripping CD's. > > > > Name a single program (not using libscg) that implements user space SCSI and runs > > on as many platforms as cdrecord/libscg does. > > > I have 2 technical questions, and I hope that you will take the time > to answer them. > > 1) extract from the README of the latest stable cdrtools package: > > Linux driver design oddities ****************************************** > Although cdrecord supports to use dev=/dev/sgc, it is not recommended > and it is unsupported. > > The /dev/sg* device mapping in Linux is not stable! Using dev=/dev/sgc > in a shell script may fail after a reboot because the device you want > to talk to has moved to /dev/sgd. For the proper and OS independent > dev=,, syntax read the man page of cdrecord. > > My understanding of that is you say to not use dev=/dev/sgc because it > isn't stable. Now that you've said that bus,tgt,lun is not stable on > Linux (because of a "Linux bug") why is the b,t,l scheme preferred > over the /dev/sg* one ? b,t,l _is_ stable as long as the OS does a reasonable and orthogonal work. This was true until ~ 2001, when Linux introduced unstable USB handling. Note that this fact is not a failure from libscg but from Linux. > 2) design question: > > - cdrecord scans then maps the device to the b,t,l scheme. > - the libsg uses the b,t,l ids in its interface to perform the operations > > So now, if cdrecord could have a new option called -scanbusmap that > displays the mapping it performs in a way that people can parse the > output, I think that will solve most issues. The output of cdrecord -scanbus is already parsable, so what is your point? Jörg -- EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin js@cs.tu-berlin.de (uni) schilling@fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/ URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily