Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261500AbUFTTeu (ORCPT ); Sun, 20 Jun 2004 15:34:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263709AbUFTTeu (ORCPT ); Sun, 20 Jun 2004 15:34:50 -0400 Received: from mail1.kontent.de ([81.88.34.36]:25835 "EHLO Mail1.KONTENT.De") by vger.kernel.org with ESMTP id S261500AbUFTTes convert rfc822-to-8bit (ORCPT ); Sun, 20 Jun 2004 15:34:48 -0400 From: Oliver Neukum To: James Bottomley Subject: Re: DMA API issues Date: Sun, 20 Jun 2004 21:34:52 +0200 User-Agent: KMail/1.6.2 Cc: Ian Molton , rmk+lkml@arm.linux.org.uk, david-b@pacbell.net, Linux Kernel , greg@kroah.com, tony@atomide.com, jamey.hicks@hp.com, joshua@joshuawise.com References: <1087584769.2134.119.camel@mulgrave> <200406202002.47025.oliver@neukum.org> <1087759622.10858.97.camel@mulgrave> In-Reply-To: <1087759622.10858.97.camel@mulgrave> MIME-Version: 1.0 Content-Disposition: inline Content-Type: Text/Plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Message-Id: <200406202134.58657.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1365 Lines: 36 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Am Sonntag, 20. Juni 2004 21:27 schrieb James Bottomley: > On Sun, 2004-06-20 at 13:02, Oliver Neukum wrote: > > > The DMA API is about allowing devices to transact directly with memory > > > behind the memory controller, it's an API that essentially allows the > > > I/O controller and memory controller to communicate without CPU > > > intervention. This is still possible through the hypervisor, so the > > > iSeries currently fully implements the DMA API. > > > > Then what's the problem? > > If you look at the diagram, you'll see that the OHCI memory isn't behind > the memory controller... And that means what? We don't care about how memory is implemented in the machines we run on. All we care about is the consequences of the implementation. We have an area of memory here that the CPU and a subset of devices can directly access. What to do about it? Regards Oliver -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) iD8DBQFA1ebgbuJ1a+1Sn8oRAnFdAJ45v2h3fUe7NIPVxyS9CmH69vEHLgCghgQe qXQVLQOlkEabmPVqmCOaSq8= =35je -----END PGP SIGNATURE----- - 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/