From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750998AbWAYOUX (ORCPT ); Wed, 25 Jan 2006 09:20:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751170AbWAYOUX (ORCPT ); Wed, 25 Jan 2006 09:20:23 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:22554 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S1750998AbWAYOUV (ORCPT ); Wed, 25 Jan 2006 09:20:21 -0500 Date: Wed, 25 Jan 2006 15:21:55 +0100 From: Jens Axboe To: Joerg Schilling Cc: matthias.andree@gmx.de, jengelh@linux01.gwdg.de, rlrevell@joe-job.com, linux-kernel@vger.kernel.org Subject: Re: CD writing in future Linux (stirring up a hornets' nest) (was: Rationale for RLIMIT_MEMLOCK?) Message-ID: <20060125142155.GW4212@suse.de> References: <20060123165415.GA32178@merlin.emma.line.org> <1138035602.2977.54.camel@laptopd505.fenrus.org> <20060123180106.GA4879@merlin.emma.line.org> <1138039993.2977.62.camel@laptopd505.fenrus.org> <20060123185549.GA15985@merlin.emma.line.org> <43D530CC.nailC4Y11KE7A@burner> <1138048255.21481.15.camel@mindpipe> <20060123212119.GI1820@merlin.emma.line.org> <43D78585.nailD7855YVBX@burner> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <43D78585.nailD7855YVBX@burner> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 25 2006, Joerg Schilling wrote: > Jan Engelhardt wrote: > > > >1. compile a list of their requirements, > > > > Have as few code duplicated (e.g. ATAPI and SCSI may share some - after > > all, ATAPI is (to me) some sort of SCSI tunneled in ATA.) > > Thank you! This is a vote _pro_ a unified SCSI generic implementation for all > types of devices. The current implementation unneccssarily duplicates a lot > of code. The block layer SG_IO is just that, it's completely transport agnostic. There's not a lot of duplicated code. In the future, perhaps sg will disappear and be replaced by bsg which is just the full block layer implementation of that (SG_IO can currently be considered a subset of that support). > > Make it, in accordance with the above, possible to have as few kernel > > modules loaded as possible and therefore reducing footprint - if I had not > > to load sd_mod for usb_storage fun, I would get an itch to load a 78564 > > byte scsi_mod module just to be able to use ATAPI. (MINOR one, though.) > > On Solaris, the SCSI glue code (between hostadaptor drivers and target drivers) is > really small: > > /usr/ccs/bin/size /kernel/misc/scsi > 28482 + 27042 + 2036 = 57560 > > And if you check the amount of completely unneeded code Linux currently has > just to implement e.g. SG_IO in /dev/hd*, it could even _save_ space in the > kernel when converting to a clean SCSI based design. Please point me at that huge amount of code. Hint: there is none. Deja vu, anyone? -- Jens Axboe