From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH] set CONFIG_SCSI_MULTI_LUN by default and update help Date: Sun, 3 May 2009 09:24:08 -0600 Message-ID: <20090503152408.GT8822@parisc-linux.org> References: <49FDA2CA.4040601@tremplin-utc.net> <1241362635.5596.34.camel@mulgrave.int.hansenpartnership.com> <20090503151153.GS8822@parisc-linux.org> <1241364068.5596.55.camel@mulgrave.int.hansenpartnership.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from palinux.external.hp.com ([192.25.206.14]:33369 "EHLO mail.parisc-linux.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754428AbZECPYI (ORCPT ); Sun, 3 May 2009 11:24:08 -0400 Content-Disposition: inline In-Reply-To: <1241364068.5596.55.camel@mulgrave.int.hansenpartnership.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: ?ric Piel , linux-scsi@vger.kernel.org, Alan Stern On Sun, May 03, 2009 at 10:21:08AM -0500, James Bottomley wrote: > On Sun, 2009-05-03 at 09:11 -0600, Matthew Wilcox wrote: > > On Sun, May 03, 2009 at 09:57:15AM -0500, James Bottomley wrote: > > > Actually, I'd really rather not alter the default value of this setting. > > > Multi-lun is rapidly becoming obsolete: any modern devices conforming to > > > SCSI-3 use REPORT LUNS instead of doing LUN scanning, which gets us out > > > of the issue. Conversely, the ancient devices which rely on correctly > > > setting this are more likely to get upset about any change in the > > > balance. > > > > Yes, but USB devices are prohibited from being SCSI-3 devices, so it's > > not becoming obsolete. > > No they're not, there's nothing in the USB specs that say this. UAS > will specifically require it. I didn't mean "prohibited by the USB spec", I meant "prohibited by Linux", for the exact reason you say below. > The problem is we don't trust USB manufacturers with standards > compliance any further than they could spit a rat, so we assume when > they say they conform to SCSI-3 or above that they must have got it > wrong and push it back down to SCSI-2. > > Because of this, no-one actually knows how many working SCSI-3 USB > devices we might have supported. This is true. Suggestions for a better way to handle USB devices ... ? -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."