From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030742AbWKULZ0 (ORCPT ); Tue, 21 Nov 2006 06:25:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S966961AbWKULZ0 (ORCPT ); Tue, 21 Nov 2006 06:25:26 -0500 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:38096 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S966964AbWKULZZ (ORCPT ); Tue, 21 Nov 2006 06:25:25 -0500 Date: Tue, 21 Nov 2006 11:28:29 +0000 From: Alan To: Ray Lee Cc: Larry Finger , LKML Subject: Re: Problem with DMA on x86_64 with 3 GB RAM Message-ID: <20061121112829.19a9c043@localhost.localdomain> In-Reply-To: <456282DE.1000407@madrabbit.org> References: <455B63EC.8070704@madrabbit.org> <20061118112438.GB15349@nineveh.rivenstone.net> <1163868955.27188.2.camel@johannes.berg> <455F3D44.4010502@lwfinger.net> <455F4271.1060405@madrabbit.org> <455FF672.4070502@lwfinger.net> <456282DE.1000407@madrabbit.org> X-Mailer: Sylpheed-Claws 2.6.0 (GTK+ 2.8.20; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > Confused. As in, once the bcm43xx module initcall happens? Or without bcm43xx > at all? If the former, is the behavior different when built as a module versus > built-in? (ie, are there ordering problems.) The pci_dma code on the x86_64 platform is broken for the case of PCI devices with < 32bit DMA. Has been forever, this is a problem with various devices, although most of the others are obsolete except for the bcm43xx and b44 (the latter has hacks to work around the x86-64 brokenness). At the very least the pci_set_dma_mask should error in this situation or switch to using GFP_DMA (24bit) memory spaces. Having it error isn't the whole solution as you still need some way to handle the "what do I do next". Alan