Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753157AbYFUOBp (ORCPT ); Sat, 21 Jun 2008 10:01:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751105AbYFUOBe (ORCPT ); Sat, 21 Jun 2008 10:01:34 -0400 Received: from smtp-out04.alice-dsl.net ([88.44.63.6]:34142 "EHLO smtp-out04.alice-dsl.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751132AbYFUOAv (ORCPT ); Sat, 21 Jun 2008 10:00:51 -0400 To: Alan Stern Cc: Kernel development list , AntonioLin , David Vrabel Subject: Re: Scatter-gather list constraints From: Andi Kleen References: Date: Sat, 21 Jun 2008 15:59:51 +0200 In-Reply-To: (Alan Stern's message of "Fri, 20 Jun 2008 16:30:25 -0400 (EDT)") Message-ID: <87fxr6yjl4.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-OriginalArrivalTime: 21 Jun 2008 13:52:36.0414 (UTC) FILETIME=[0FDB95E0:01C8D3A6] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 852 Lines: 19 Alan Stern writes: > This question arises in connection with wireless USB mass-storage > devices. The controller driver requires that all DMA segments > in a transfer, other than the last one, have a multiple of 1024 bytes. > But we're sometimes getting s-g lists where an element contains an odd > number of 512-byte sectors, and of course it doesn't work. But you can handle a single 512 byte request? Splitting the request in this case should work. Or maybe copying is cheaper than splitting? I don't think the block layer knows about such kinds of restrictions. -Andi -- 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/