From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: Using netconsole for debugging suspend/resume Date: Tue, 13 Jun 2006 06:54:14 +0200 Message-ID: <200606130654.14477.ak@suse.de> References: <200606121746.34880.ak@suse.de> <200606130547.49624.ak@suse.de> <20060612.214948.124554804.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: jeremy@goop.org, lkml@rtr.ca, mpm@selenic.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: Received: from mx2.suse.de ([195.135.220.15]:56470 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S1752294AbWFME5B (ORCPT ); Tue, 13 Jun 2006 00:57:01 -0400 To: David Miller In-Reply-To: <20060612.214948.124554804.davem@davemloft.net> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tuesday 13 June 2006 06:49, David Miller wrote: > From: Andi Kleen > Date: Tue, 13 Jun 2006 05:47:49 +0200 > > > I've been playing with the idea of writing "early1394" that just > > turns the DMA controller on as early as possible similar to earlyprintk > > on the target. Then it would be possible to use it for early > > debugging too. But so far it's not done yet. > > Does this raw1394 thing with firescope just assume DMA address == > physical address? Yes. > How would it work to access all of physical > memory properly on IOMMU platforms? It assumes you don't have an IOMMU - relies on all memory being accessible by ohci1394. On x86-64 it can't access > 4GB also, but that's normally ok because the kernel log buffer is below that. I guess if you use 1394 with remote DMA for other protocols (like video etc.) there must be some way for the subsystem to map the memory even on IOMMU systems. I admit I haven't dived that deeply into the 1394 subsystem so I don't know how that works. -Andi