Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754690AbYG3TVo (ORCPT ); Wed, 30 Jul 2008 15:21:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754495AbYG3TVe (ORCPT ); Wed, 30 Jul 2008 15:21:34 -0400 Received: from idcmail-mo2no.shaw.ca ([64.59.134.9]:30471 "EHLO pd5mo1no-dmz.prod.shaw.ca" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754492AbYG3TVd (ORCPT ); Wed, 30 Jul 2008 15:21:33 -0400 X-Cloudmark-SP-Filtered: true X-Cloudmark-SP-Result: v=1.0 c=0 a=dkSNLZc3JAWxmWpFRhoA:9 a=nz7t8EDBJrqaCecqCqpDuyP7W3UA:4 Message-ID: <4890BF39.6060608@shaw.ca> Date: Wed, 30 Jul 2008 13:21:29 -0600 From: Robert Hancock User-Agent: Thunderbird 2.0.0.16 (Windows/20080708) MIME-Version: 1.0 To: "V.Radhakrishnan" CC: Sanka Piyaratna , Alan Cox , linux-kernel@vger.kernel.org Subject: Re: PCIe device driver question References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 710 Lines: 15 V.Radhakrishnan wrote: >>> am testing this in an X86_64 architecture machine with 4 GB of RAM. I >>> am able to successfully dma data into any memory (dma) address > >>> 0x0000_0001_0000_0000. > > How can you DMA "successfully" into this address which is > 4 GB when > you have only 4 GB RAM ? Or am I missing something ? The MMIO and other reserved memory space at the top of the 32-bit memory space will cause the top part of memory to be relocated above 4GB. -- 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/