From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCH 1/2] scsi: Add scsi_device max_cmd_len Date: Wed, 29 Mar 2006 18:19:16 -0500 Message-ID: <442B15F4.30506@pobox.com> References: <200603282217.k2SMHJTH032251@d03av04.boulder.ibm.com> <20060329091104.GB7940@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20060329091104.GB7940@infradead.org> Sender: linux-scsi-owner@vger.kernel.org To: Christoph Hellwig Cc: Brian King , James.Bottomley@steeleye.com, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org List-Id: linux-ide@vger.kernel.org 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. Jeff