From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniela Engert Subject: Re: [PATCH] libata: rewrite SCSI host scheme to be one per ATA host Date: Wed, 22 Apr 2009 17:10:55 +0200 Message-ID: <49EF337F.1030804@ngrt.de> References: <20090422090929.GA14928@havoc.gtf.org> <49EEE225.3010700@garzik.org> <49EF0A92.1070400@panasas.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <49EF0A92.1070400@panasas.com> Sender: linux-scsi-owner@vger.kernel.org To: Boaz Harrosh Cc: Jeff Garzik , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, LKML , Jens Axboe , Tejun Heo List-Id: linux-ide@vger.kernel.org Boaz Harrosh wrote: > On 04/22/2009 12:23 PM, Jeff Garzik wrote: >> Jeff Garzik wrote: >>> Currently, libata creates a Scsi_Host per port. This was originally >>> done to leverage SCSI's infrastructure to arbitrate among master/slave >>> devices, but is not needed for most modern SATA controllers. And I >>> _think_ it is not needed for master/slave if done properly, either. >>> It may work with other controllers -- TRY AT YOUR OWN RISK. It will >>> probably fail for master/slave configurations, and SAS & PMP also >>> need looking at. It yielded this lsscsi output on my AHCI box: >>> >>> [0:0:0:0] disk ATA ST3500320AS SD15 /dev/sda >>> [0:2:0:0] disk ATA G.SKILL 128GB SS 02.1 /dev/sdb >>> [0:5:0:0] cd/dvd PIONEER BD-ROM BDC-202 1.04 /dev/sr0 >> For comparison, here is unmodified 2.6.30-rc3: >> >> [jgarzik@bd ~]$ lsscsi >> [0:0:0:0] disk ATA ST3500320AS SD15 /dev/sda >> [2:0:0:0] disk ATA G.SKILL 128GB SS 02.1 /dev/sdb >> [5:0:0:0] cd/dvd PIONEER BD-ROM BDC-202 1.04 /dev/sr0 >> > > Could the master/slave be simply solved by emulating a SCSI LUN Don't forget, there are ATAPI devices (some Sony CD burners and old phase-changers come into mind) which *do* have multiple LUNs sitting beyond the PATA port. I don't know if libata supports such setups (my old OS/2 driver does) but one shouldn't hijack LUNs to emulate targets. Ciao, Dani