From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752507AbYDECmW (ORCPT ); Fri, 4 Apr 2008 22:42:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751353AbYDECmG (ORCPT ); Fri, 4 Apr 2008 22:42:06 -0400 Received: from smtp120.sbc.mail.sp1.yahoo.com ([69.147.64.93]:40632 "HELO smtp120.sbc.mail.sp1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751003AbYDEClm (ORCPT ); Fri, 4 Apr 2008 22:41:42 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=pacbell.net; h=Received:X-YMail-OSG:X-Yahoo-Newman-Property:From:To:Subject:Date:User-Agent:Cc:References:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding:Content-Disposition:Message-Id; b=FalAvHNoCZuu1mWBu5YnblyUJa478tdQTvrtQd/kgktyBjRbZeZ+njPmTGYzYAbHdqzEa0GtzLnO23s5n2dcIkDsCa4j1pbEtcsN8hqbtWsLi3RJXPCFOUmDNrgmPmtgYnZsj3Z2DmRuG3p0athzBuXtb7rC+JFbAF7Lr2CZ4dw= ; X-YMail-OSG: Nq3V04YVM1m3qvIne52CIApwD7CZlF3Fr8C7N8YgxG1RoihhheyRwTtGWFasWv0tJVHX8cV9zQ-- X-Yahoo-Newman-Property: ymail-3 From: David Brownell To: Andrew Morton Subject: Re: [PATCH] jffs2 summary allocation Date: Fri, 4 Apr 2008 19:41:34 -0700 User-Agent: KMail/1.9.6 Cc: "Kyungmin Park" , "Josh Boyer" , linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, "Michael Trimarchi" , spi-devel-general@lists.sourceforge.net, dwmw2@infradead.org, linux-arm-kernel@lists.arm.linux.org.uk References: <713171.37644.qm@web26213.mail.ukl.yahoo.com> <9c9fda240804041829r5a768b39n340926485aa12687@mail.gmail.com> <20080404184615.deaf3122.akpm@linux-foundation.org> In-Reply-To: <20080404184615.deaf3122.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200804041941.35075.david-b@pacbell.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 04 April 2008, Andrew Morton wrote: > This problem comes up pretty often. Which problem -- kmalloc(BIG)? Or dma(dma-unsafe-mem)? Or something else? The specific issue here might best be described as JFFS2 making a bad assumption: that MTD drivers never use DMA. The I2C stack does that in some cases (for example, I/O buffers in i2c_smbus_xfer_emulated are on-stack), but I'd not call that an especially common assumption. > Rather than open-coding it yet again > it'd be nice to have a little bit of library code which manages an array of > pages and which has accessors for common operations like > read/write-u8/u16/u32/u64, memset, memcpy, etc. If array-of-pages is to be more widely adopted, that'd make sense. The MTD framework is a bit odd in that respect ... it has block devices but doesn't use the scatterlist primitives. - Dave