From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian King Subject: Re: [PATCH 1/2] scsi: Add scsi_device max_cmd_len Date: Thu, 30 Mar 2006 10:39:04 -0600 Message-ID: <442C09A8.50200@us.ibm.com> References: <200603282217.k2SMHJTH032251@d03av04.boulder.ibm.com> <20060329091104.GB7940@infradead.org> <442B15F4.30506@pobox.com> Reply-To: brking@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <442B15F4.30506@pobox.com> Sender: linux-scsi-owner@vger.kernel.org To: Jeff Garzik Cc: Christoph Hellwig , James.Bottomley@steeleye.com, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org List-Id: linux-ide@vger.kernel.org Jeff Garzik wrote: > James Bottomley wrote: >> This really doesn't look correct. What you want is a sata transport >> class with a max command length in the host device. > > Christoph Hellwig wrote: >> this sounds wrong to me. cdb length is a limitation of the host (driver). >> A target will reject unknown commands, no matter what length they have. > > > In practice, CDB length may be limited by both the host and the device. > This applies to ATAPI, and some USB storage too IIRC. For ATAPI, you > read the CDB length from the device's IDENTIFY PACKET DEVICE info page. So the question remains, do we need to police the CDB length on a per device basis, or is a per host basis ok? Will we have ATAPI devices falling on the floor if they get sent too large of a cdb? Brian -- Brian King eServer Storage I/O IBM Linux Technology Center