From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH 1/4] block: use ARCH_KMALLOC_MINALIGN as the default dma pad mask Date: Tue, 20 May 2008 02:52:31 -0700 Message-ID: <20080520025231.b88bc71d.akpm@linux-foundation.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> <20080520093819.GA9147@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080520093819.GA9147@gondor.apana.org.au> Sender: linux-ide-owner@vger.kernel.org To: Herbert Xu 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 List-Id: linux-scsi@vger.kernel.org On Tue, 20 May 2008 17:38:20 +0800 Herbert Xu wrote: > On Tue, May 20, 2008 at 02:31:29AM -0700, Andrew Morton wrote: > > > > So here you're using it for "dma aligment" whereas crypto is using it > > (or ARCH_SLAB_MINALIGN!) for "cpu 64-bit alignment". > > No the 64-bit alignment is just an example. The purpose of > CRYPTO_MINALIGN is pretty much the same as ARCH_KMALLOC_MINALIGN, > i.e., the minimum alignment guaranteed by kmalloc. The only > reason it exists is because ARCH_KMALLOC_MINALIGN isn't defined > on all platforms. I'm struggling to understand what you're saying here. The comment you have there over the CRYPTO_MINALIGN definition is quite specific. Is it wrong? Whether the mapping between CRYPTO_MINALIGN and ARCH_KMALLOC_MINALIGN is abusive is (I find) hard to say, because first one would need to be able to say what ARCH_KMALLOC_MINALIGN is for. I expect it was for DMA purposes.