From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: PMP and SEMB messages to SEP Date: Mon, 17 Jan 2011 18:18:36 +0100 Message-ID: <20110117171836.GI27123@htj.dyndns.org> References: <20110113192558.GE16039@MAIL.13thfloor.at> <20110114142018.GA978@htj.dyndns.org> <20110114165957.GH16039@MAIL.13thfloor.at> <20110114170407.GE978@htj.dyndns.org> <20110114173759.GI16039@MAIL.13thfloor.at> <20110117154042.GG27123@htj.dyndns.org> <1295281131.3015.44.camel@mulgrave.site> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:52586 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752131Ab1AQRSl (ORCPT ); Mon, 17 Jan 2011 12:18:41 -0500 Content-Disposition: inline In-Reply-To: <1295281131.3015.44.camel@mulgrave.site> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: James Bottomley Cc: Herbert Poetzl , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org Hello, James. On Mon, Jan 17, 2011 at 10:18:51AM -0600, James Bottomley wrote: > > The problem is that the PMP device itself is currently not allocated a > > userland visible device, so it doesn't have any /dev/* node. Hmmm... > > So perhaps it should be. If you look at the equivalent topology on SAS, > our expanders have a bsg device node precisely so that we can do this. > > That said, SAS expanders have a defined protocol (SAS Management > Protocol) to talk to the outside world, so they are real visible objects > always in our topology ... I'm not sure PMP has this ... it seems that > all PMP visibility is an extension to the standard? SATA PMP is mostly a dumb switch and there isn't much which can be done by issuing custom commands (and IIRC we didn't have bsg back then), so it was never made visible to userland, but yeah probably exporting a bsg node is a good idea. Inside libata, the PMP device has its device representation and all so it shouldn't be too difficult either. Not really sure how the inquiry and stuff should be handled tho. Thanks. -- tejun