From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Dharm Subject: Re: [example PATCH - not for applying] exclude certain commands Date: Thu, 24 Apr 2003 11:22:00 -0700 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20030424112200.A10511@one-eyed-alien.net> References: Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-md5; protocol="application/pgp-signature"; boundary="X1bOJ3K7DJ5YkBrT" Return-path: Received: from ziggy.one-eyed-alien.net ([64.169.228.100]:39432 "EHLO ziggy.one-eyed-alien.net") by vger.kernel.org with ESMTP id S263709AbTDXSKB (ORCPT ); Thu, 24 Apr 2003 14:10:01 -0400 Content-Disposition: inline In-Reply-To: ; from Andries.Brouwer@cwi.nl on Thu, Apr 24, 2003 at 11:08:12AM +0200 List-Id: linux-scsi@vger.kernel.org To: Andries.Brouwer@cwi.nl Cc: James.Bottomley@steeleye.com, afafc@rnl.ist.utl.pt, alan@lxorguk.ukuu.org.uk, greg@kroah.com, linux-scsi@vger.kernel.org, linux-usb-devel@lists.sourceforge.net, mike@hingston.demon.co.uk, stelian@popies.net, torvalds@transmeta.com --X1bOJ3K7DJ5YkBrT Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Apr 24, 2003 at 11:08:12AM +0200, Andries.Brouwer@cwi.nl wrote: > From: Matthew Dharm >=20 > > Comments? >=20 > My only comment is that your sample of failed cases primarily seems to > address those devices that support some variant of MODE_SENSE -- ther= e are > lots of devices that don't support it at all, which is why I wanted to > filter it with the (apparently) now-dead command filter concept. >=20 > Well, before we create a new infrastructure it is a good idea > to make sure that it is needed. James mentioned three cases > in Bugzilla and it looks like these are fixed by a small correction > to the MODE_SENSE to MODE_SENSE_10 translation. >=20 > You mention lots of devices that don't support MODE_SENSE at all. > Do you have Bugzilla or l-k / l-s / l-u refs? Unfortunately, my data comes from (a) working with this junk for several years, and (b) non-public conversations with hardware vendors. While there linux-usb-devel/users references, you'll have to google for logs to find them. Yeah, I know that's a lousy answer. But try to realize that I've been dealing with a long, slow, and painful discovery process of what the 'popular OS' uses. > (Smart Media and similar cards come with a write protect bit. > I would suppose reporting it is supported by most non-broken hardware. > We get it from the header of the MODE_SENSE return value. > So there is some reason to expect that MODE_SENSE[_10] is supported, > at least in the minimum form where no page but only the header > is returned. Closer investigation of other error cases might reveal > more usb-storage flaws.) This is actually interesting... smart media readers seem to be some of the worst offenders in terms of not supporting this command (or at least a variant of it that I've been able to discover). Hardware vendors tell me that those which build devices based on older designs (i.e. real SCSI or ATAPI) do support some version of a modesense because it carried over from their older designs. Those which are doing new designs from the ground up do not support it, as apparently neither Windows nor MacOS check for write-protect this way. Or so I'm told by the people who design these things. Matt --=20 Matthew Dharm Home: mdharm-usb@one-eyed-alien.= net=20 Maintainer, Linux USB Mass Storage Driver Ye gods! I have feet??! -- Dust Puppy User Friendly, 12/4/1997 --X1bOJ3K7DJ5YkBrT Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE+qCtHIjReC7bSPZARAg6QAJ9lrK8K9aWLS/CZJ0h9PzMIhvqswQCfRch4 WSNvof62bllvW1lAyXX2YQk= =7dHu -----END PGP SIGNATURE----- --X1bOJ3K7DJ5YkBrT--