From mboxrd@z Thu Jan 1 00:00:00 1970 From: FUJITA Tomonori Subject: Re: [PATCH 3/3] iscsi_tcp: Enable large commands Date: Tue, 15 Apr 2008 22:46:41 +0900 Message-ID: <20080415224639Q.tomof@acm.org> References: <48049E8A.7030700@panasas.com> <4804A16D.7000002@panasas.com> <4804A8C7.504@emulex.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mo10.iij4u.or.jp ([210.138.174.78]:54123 "EHLO mo10.iij4u.or.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758990AbYDONtD (ORCPT ); Tue, 15 Apr 2008 09:49:03 -0400 In-Reply-To: <4804A8C7.504@emulex.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James.Smart@Emulex.Com Cc: bharrosh@panasas.com, fujita.tomonori@lab.ntt.co.jp, James.Bottomley@HansenPartnership.com, michaelc@cs.wisc.edu, linux-scsi@vger.kernel.org, jens.axboe@oracle.com, bzolnier@gmail.com, agk@redhat.com, Geert.Uytterhoeven@sonycom.com On Tue, 15 Apr 2008 09:08:23 -0400 James Smart wrote: > Boaz Harrosh wrote: > > Let through up to the largest command of 260 defined by the scsi standard. > > iscsi core supports this already. Now that the scsi-ml supports it we can > > start using large commands. > > Just to double-check: > if we use sg_io to pass through requests from user-land, which are addressed to > drivers or transports, and which may not be a SCSI command but rather just something > utilizing the sg_io infrastructure for management or pass-thru, are we limited to > 260 bytes for request/cmd payload ? With SG_IO (block, sg.c, and bsg), the command length is still limited to 16 bytes (BLK_MAX_CDB). We will remove the limit in bsg shortly. As you know, bsg supports bidi data transfer and there is no limit on the length of request and response payload. SAS management protocol uses request and response payload for data transfer. It doesn't use the command area (that is used for SCSI command).