From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 2/3] Add EVPD page 0x83 to sysfs Date: Fri, 7 Mar 2014 02:43:21 -0800 Message-ID: <20140307104321.GA28472@infradead.org> References: <1392286032-85036-1-git-send-email-hare@suse.de> <1392286032-85036-3-git-send-email-hare@suse.de> <20140228170131.GA31510@infradead.org> <5316D459.6070107@suse.de> <20140305194255.GA5607@infradead.org> <53183951.7080805@suse.de> <1394188800.5225.41.camel@dabdike> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from bombadil.infradead.org ([198.137.202.9]:40014 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751945AbaCGKnZ (ORCPT ); Fri, 7 Mar 2014 05:43:25 -0500 Content-Disposition: inline In-Reply-To: <1394188800.5225.41.camel@dabdike> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Hannes Reinecke , Christoph Hellwig , linux-scsi@vger.kernel.org, Jeremy Linton , Kay Sievers , Doug Gilbert , Kai Makisara On Fri, Mar 07, 2014 at 02:40:00PM +0400, James Bottomley wrote: > On Thu, 2014-03-06 at 10:01 +0100, Hannes Reinecke wrote: > > So the only 'proper' solution would be to add a bitmap of supported > > pages; however, this would be 256 bits = 32 bytes of additional > > space required for struct sdev. > > Which I'm a bit reluctant do to, as it'll be a sparse array in most > > cases, adding to quite some wasted space. > > Why per sdev? Isn't it per target? The supported EVPD page list > shouldn't really vary for luns of the same target unless something very > strange is happening in the array. It might very well vary. For one difference device types support different EVPD patches and a target might mix and match device types for LUNs. Also software targets might use individual LUNs as passthrough to physical devices, in which case they might support different EVPD pages even for the same device type. E.g. the pscsi backend for the in-kernel target might behave like that.