Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754875Ab1EYUVY (ORCPT ); Wed, 25 May 2011 16:21:24 -0400 Received: from hyde.gogi.tv ([87.106.161.174]:36423 "EHLO hyde.gogi.tv" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751754Ab1EYUVX (ORCPT ); Wed, 25 May 2011 16:21:23 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 25 May 2011 21:21:21 +0100 From: Daniel Haid To: Konrad Rzeszutek Wilk Cc: Andi Kleen , Subject: Re: Question about iommu on =?UTF-8?Q?x=38=36=5F=36=34=20and=20ra?= =?UTF-8?Q?deon=20driver=2E?= In-Reply-To: <20110525125752.GB3467@dumpdata.com> References: <6ac3f6faad655602b767aa14b355e982@admin.gogi.tv> <20110523220536.GB11961@dumpdata.com> <756073831c36e0404199a4e8239bcb70@admin.gogi.tv> <08370791664f069624d25c757ed101c0@admin.gogi.tv> <20110525125752.GB3467@dumpdata.com> Message-ID: User-Agent: Roundcube Webmail/0.4.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 753 Lines: 20 > Only if you allow 3GB or less in the machine. So you would have to do > mem=3G as well. > > The reason is that (and you can see that yourself by looking at the > E820), is that 1GB is actually _above_ the 4GB. Just another question on this one: Why can a driver not simply ask for DMA-capable memory, is this not what memory zones are for? So if a driver wants to do DMA it requests DMA-memory and gets it from the lower than 4GB address space. But for some reason it is not done like this, why? -- 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/