From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Mundt Subject: Re: [PATCH 1/4] block: use ARCH_KMALLOC_MINALIGN as the default dma pad mask Date: Tue, 20 May 2008 18:55:12 +0900 Message-ID: <20080520095512.GA18633@linux-sh.org> References: <1211259514-9131-1-git-send-email-fujita.tomonori@lab.ntt.co.jp> <1211259514-9131-2-git-send-email-fujita.tomonori@lab.ntt.co.jp> <20080520023129.2f921f24.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mta23.gyao.ne.jp ([125.63.38.249]:38876 "EHLO mx.gate01.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1765349AbYETJ5M (ORCPT ); Tue, 20 May 2008 05:57:12 -0400 Content-Disposition: inline In-Reply-To: <20080520023129.2f921f24.akpm@linux-foundation.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Andrew Morton Cc: FUJITA Tomonori , linux-scsi@vger.kernel.org, linux-ide@vger.kernel.org, jens.axboe@oracle.com, tsbogend@alpha.franken.de, bzolnier@gmail.com, James.Bottomley@HansenPartnership.com, jeff@garzik.org, davem@davemloft.net, linux-mm@kvack.org, Herbert Xu On Tue, May 20, 2008 at 02:31:29AM -0700, Andrew Morton wrote: > Why does ARCH_KMALLOC_MINALIGN even exist? What is its mandate? Sigh. > > It's not really related to your patch (although your patch compounds > the problem a little). But we should sit down and work out what we > actually want to do here. Something like: > > In each architecture's arch/foo/Kconfig, define > > CONFIG_ARCH_DMA_ALIGN > > and > > CONFIG_ARCH_64BIT_POINTER_ALIGN > > and then use them. Note that these have nothing to do with each other, > as far as I can tell. > > Which leaves the question: "what should slab use"? Maybe > CONFIG_ARCH_DMA_ALIGN? But that depends what ARCH_KMALLOC_MINALIGN is > supposed to exist for. > > ick. > The only platforms that set ARCH_KMALLOC_MINALIGN appear to do so for DMA alignment reasons, so your Kconfig option there seems reasonable. The ARCH_SLAB_MINALIGN you can blame me for: http://marc.info/?l=linux-kernel&m=110227138116749&w=2