Re: [PATCH 1/4] block: use ARCH_KMALLOC_MINALIGN as the default dma pad mask

David Miller
2008-05-22T01:19:50Z

From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Date: Thu, 22 May 2008 10:14:12 +0900

> On Wed, 21 May 2008 21:18:11 +0800
> Herbert Xu <herbert@gondor.apana.org.au> wrote:
>
> > On Wed, May 21, 2008 at 09:46:24PM +0900, FUJITA Tomonori wrote:
> > >
> > > No, you misunderstand my question. I meant, software algorithms don't
> > > need ARCH_KMALLOC_MINALIGN alignment for __crt_ctx and if we are fine
> > > with using the ALIGN hack for crypto hardware every time (like
> > > aes_ctx_common), crypto doesn't need ARCH_KMALLOC_MINALIGN alignment
> > > for __crt_ctx. Is this right?
> >
> > The padlock isn't the only hardware device that will require
> > such alignment. Now that we have the async interface there will
> > be more.
>
> Ok, so it's all about crypto hardware requirement. In other words, if
> we accept for potential performance drop of crypto hardware, crypto
> can drop this alignment.

It sounds to me that Herbert is saying that the VIA crypto hardware
will malfunction if not given an aligned address, rather than simply
go more slowly.