Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751835AbXBRS37 (ORCPT ); Sun, 18 Feb 2007 13:29:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751829AbXBRS37 (ORCPT ); Sun, 18 Feb 2007 13:29:59 -0500 Received: from mailhub.fokus.fraunhofer.de ([193.174.154.14]:32992 "EHLO mailhub.fokus.fraunhofer.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751831AbXBRS36 (ORCPT ); Sun, 18 Feb 2007 13:29:58 -0500 Date: Sun, 18 Feb 2007 19:27:23 +0100 From: Joerg.Schilling@fokus.fraunhofer.de (Joerg Schilling) To: stern@rowland.harvard.edu, dougg@torque.net Cc: linux-kernel@vger.kernel.org, jens.axboe@oracle.com, James.Bottomley@steeleye.com Subject: Re: [PATCH] Block layer: separate out queue-oriented ioctls Message-ID: <45d89a8b.QpxTpRwQB4A12sQN%Joerg.Schilling@fokus.fraunhofer.de> References: In-Reply-To: User-Agent: nail 11.22 3/20/05 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1519 Lines: 34 Alan Stern wrote: > > Alternatively the SG_GET_RESERVED_SIZE ioctl could be > > modified to yield no more than max_sectors*512 . > > There should be one single ioctl which can be applied uniformly to all > CD-type devices (in fact, to all devices using a request_queue) to learn > max_sectors. This rules out using SG_GET_RESERVED_SIZE. This has nothing to do with CD-type devices! It is related to SCSI tansport. > Furthermore, if you changed SG_GET_RESERVED_SIZE in this way you would > only increase the confusion. The reserved size isn't directly related to > the maximum allowed DMA length, and there's no point pretending it is. > What if it turns out that the reserved size is smaller than max_sectors? > Then you'd force user programs to do I/O in chunks that were smaller than > necessary. It would not increase confusion but reduce confusion because all programs would later behave correctly without the need to change them. J?rg -- EMail:joerg@schily.isdn.cs.tu-berlin.de (home) J?rg Schilling D-13353 Berlin js@cs.tu-berlin.de (uni) schilling@fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/ URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/