From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH 0/4] scsi: 64-bit LUN support Date: Wed, 27 Mar 2013 08:37:00 +0100 Message-ID: <5152A19C.7010500@suse.de> References: <1361261883-41467-1-git-send-email-hare@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cantor2.suse.de ([195.135.220.15]:33155 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752706Ab3C0HhE (ORCPT ); Wed, 27 Mar 2013 03:37:04 -0400 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Chad Dupuis Cc: "linux-scsi@vger.kernel.org" , James Bottomley , Jeremy Linton , Robert Elliott , Bart Van Assche On 03/26/2013 07:00 PM, Chad Dupuis wrote: > > > On Tue, 19 Feb 2013, Hannes Reinecke wrote: > >> This patchset updates the SCSI midlayer to use 64-bit LUNs >> internally. >> It eliminates the need to limit the number of LUNs artificially to >> avoid aliasing issues; the SCSI midlayer can now accept any LUN >> presented >> to it. >> >> The LLDD specific settings for 'max_lun' have been left untouched; >> it should be raised to '~0' if the HBA supports 64-bit LUNs >> internally. >> However, it is up to the driver maintainer to raise that limit. >> >> Hannes Reinecke (4): >> scsi_scan: Fixup scsilun_to_int() >> scsi: use 64-bit LUNs >> scsi: use 64-bit value for 'max_luns' >> scsi: Remove CONFIG_SCSI_MULTI_LUN >> > > Hannes, > > As we've reviewed these patches internally, the one question that kee= ps > coming up is how do we handle hardware that cannot handle a 64-bit LU= N > address? For example, some of our older 2G/bps hardware can only > handle a 16-bit LUN address. Currently we convert the u32 value to u= 16. > Do we do the same for the 64-bit conversion? Can a way be=20 devised to > "opt-out" of receiving a 64-bit address in the first place (IIRC this > was an option in the v1 patch set)? > Yes, you can. The idea here is to let 'max_luns' control this behaviour;=20 'max_luns' is the highest LUN number the host can support. So for 16-bit LUN you would set max_luns to '0xFFFF', and for 32-bit LUN addresses you would be setting max_luns to '0xFFFFFFFF'. However, since you mention it, maybe I should add a 'scsilun_to_u32' conversion routine, as this is requested in several places. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: J. Hawn, J. Guild, F. Imend=F6rffer, HRB 16746 (AG N=FCrnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html