Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757804Ab0DIVX3 (ORCPT ); Fri, 9 Apr 2010 17:23:29 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:38338 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757769Ab0DIVXX (ORCPT ); Fri, 9 Apr 2010 17:23:23 -0400 Date: Fri, 9 Apr 2010 17:23:22 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Konrad Rzeszutek Wilk cc: Pedro Ribeiro , Daniel Mack , Robert Hancock , , , Greg KH , , Subject: Re: [LKML] Re: USB transfer_buffer allocations on 64bit systems In-Reply-To: <20100409202533.GA8983@phenom.dumpdata.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1044 Lines: 29 On Fri, 9 Apr 2010, Konrad Rzeszutek Wilk wrote: > On Fri, Apr 09, 2010 at 03:34:06PM -0400, Alan Stern wrote: > > On Fri, 9 Apr 2010, Pedro Ribeiro wrote: > > > > > > The DMA pointers do indeed look sane. I wanted to take a deeper look at > > > > this and set up a 64bit system today. However, I fail to see the problem > > > > here. Pedro, how much RAM does your machine have installed? > > > > > It has 4 GB. > > > > That means DMA mapping cannot be the cause of the problem. :-( > > That isn't entirely true. The BIOS usually allocates a 256 MB ACPI/PCI hole > that is under the 4GB. > > So end up with 3.7 GB, then the 256MB hole, and then right above the 4GB > you the the remaining memory: 4.3GB. How can Pedro find out what physical addresses are in use on his system? Alan Stern -- 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/