Date: Sun, 10 Oct 2010 17:53:40 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Alexander Motin <mav@FreeBSD.org> Cc: sos@FreeBSD.org, FreeBSD-Current <freebsd-current@freebsd.org>, Andriy Gapon <avg@icyb.net.ua>, phk@FreeBSD.org Subject: Re: letting glabel recognise a media change Message-ID: <20101010155340.GQ1733@garage.freebsd.pl> In-Reply-To: <4CA4CCE3.9060408@FreeBSD.org> References: <4CA3BD7C.9080306@feral.com> <mailpost.1285845776.1043534.73790.mailing.freebsd.current@FreeBSD.cs.nctu.edu.tw> <4CA4CCE3.9060408@FreeBSD.org>
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--0Qexx6XJGNEACt6j Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Sep 30, 2010 at 08:46:11PM +0300, Alexander Motin wrote: > Andriy Gapon wrote: > > on 30/09/2010 01:28 Matthew Jacob said the following: > >> If something like that was in place, I assure you that things would st= art to use > >> it very quickly. > >=20 > > I am not sure about this. > > Because, e.g. I don't see an easy way to know that media is changed in = scsi_cd > > driver. That is, without polling. I don't consider polling to be an e= asy way for > > a number of reasons. >=20 > SATA specification defines concept of Asynchronous Notification. It is > already used by port multipliers to report about PHY events. It is also > supposed to be used by CD drives to report media change. I haven't seen > such devices yet, but hope they may appear sometimes. >=20 > And even without AN support it would be nice to implement proper > handling for SCSI "UA - media changed" errors within CAM. It still won't > be perfect without using polling, but probably still something. I'd like to know the original reason why CD device is represented by GEOM provider and not CD media. For my naive thinking CD media should be GEOM provider that we taste once the media is inserted and orphan once the media is removed. I don't see any reasons for CD device to be useful GEOM provider, but maybe I'm overlooking something. Poul-Henning or Soren, do you remember who made and why this design choice? --=20 Pawel Jakub Dawidek http://www.wheelsystems.com pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! --0Qexx6XJGNEACt6j Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (FreeBSD) iEYEARECAAYFAkyx4YQACgkQForvXbEpPzR0cQCg7Lp+sRsDQmbHM5t3NLUqH8F0 9o8An2F+2UZHWAjtP0DNvDTLbrK/TeJk =cIDJ -----END PGP SIGNATURE----- --0Qexx6XJGNEACt6j--
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