From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boaz Harrosh Subject: Re: [PATCH 3/3] iscsi_tcp: Enable large commands Date: Tue, 15 Apr 2008 16:38:02 +0300 Message-ID: <4804AFBA.1070105@panasas.com> References: <20080414010112W.tomof@acm.org> <1208170266-1676-1-git-send-email-fujita.tomonori@lab.ntt.co.jp> <48049E8A.7030700@panasas.com> <4804A16D.7000002@panasas.com> <4804A8C7.504@emulex.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from bzq-219-195-70.pop.bezeqint.net ([62.219.195.70]:35344 "EHLO bh-buildlin2.bhalevy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756419AbYDONkU (ORCPT ); Tue, 15 Apr 2008 09:40:20 -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: FUJITA Tomonori , James Bottomley , Mike Christie , linux-scsi@vger.kernel.org, Jens Axboe , Bartlomiej Zolnierkiewicz , Alasdair G Kergon , Geert Uytterhoeven On Tue, Apr 15 2008 at 16:08 +0300, 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 ? > > -- james s I think that only bsg, after the pending patches get accepted, will let you pass larger then 16 bytes commands from user-land. sg_io is I think limited to 16. However this could be fixed. (With sg_io, did you mean commands going through the sg.c driver?) The block layer imposes no limits, and so is scsi-ml. The only limits are from ULDs, and LLDs, like here, iscsi protocol does not support more then SCSI_MAX_VARLEN_CDB_SIZE (260). If you need support in any other ULD, I will be happy to help. Boaz