From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269678AbUJMLWo (ORCPT ); Wed, 13 Oct 2004 07:22:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269679AbUJMLWo (ORCPT ); Wed, 13 Oct 2004 07:22:44 -0400 Received: from caramon.arm.linux.org.uk ([212.18.232.186]:21766 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S269678AbUJMLWm (ORCPT ); Wed, 13 Oct 2004 07:22:42 -0400 Date: Wed, 13 Oct 2004 12:22:34 +0100 From: Russell King To: Pierre Ossman Cc: LKML Subject: Re: Choosing scatter/gather limits Message-ID: <20041013122234.A23105@flint.arm.linux.org.uk> Mail-Followup-To: Pierre Ossman , LKML References: <416A6623.9000105@drzeus.cx> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <416A6623.9000105@drzeus.cx>; from drzeus-list@drzeus.cx on Mon, Oct 11, 2004 at 12:53:23PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 11, 2004 at 12:53:23PM +0200, Pierre Ossman wrote: > I've been adding scatter/gather support for the MMC host driver I'm > writing. I cannot find any documentation on how to chose the limits though. It seems that you have to read the block layer code to find out what's going on with these limits. There's some documentation on it in Documentation/block/bio.txt. If it's lacking, then please send comments to the block layer people to add the necessary information. Please also note that I'm intending to make the MMC host drivers know nothing about block IO stuff, so all you'll be passed is the MMC commands and a scatter gather list - so making sure that your driver always uses blk_rq_map_sg() and works from the SG list will ensure that your driver remains easy to update. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core