From owner-freebsd-current@FreeBSD.ORG Wed Jul 21 14:59:10 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 0EEE816A4CE; Wed, 21 Jul 2004 14:59:10 +0000 (GMT) Received: from mail.qubesoft.com (gate.qubesoft.com [217.169.36.34]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4F70943D49; Wed, 21 Jul 2004 14:59:09 +0000 (GMT) (envelope-from dfr@nlsystems.com) Received: from bluebottle.qubesoft.com (bluebottle.qubesoft.com [192.168.1.2]) by mail.qubesoft.com (8.12.9/8.12.9) with ESMTP id i6LEx2kM079932; Wed, 21 Jul 2004 15:59:02 +0100 (BST) (envelope-from dfr@nlsystems.com) Received: from builder02.qubesoft.com (builder02.qubesoft.com [192.168.1.8]) i6LEx1ON072888; Wed, 21 Jul 2004 15:59:01 +0100 (BST) (envelope-from dfr@nlsystems.com) From: Doug Rabson To: Andrew Gallatin In-Reply-To: <16638.32914.509773.486468@grasshopper.cs.duke.edu> References: <16634.47272.768935.436137@grasshopper.cs.duke.edu> <200407182039.10773.dfr@nlsystems.com> <16634.54674.966908.540880@grasshopper.cs.duke.edu> <200407182104.53221.dfr@nlsystems.com> <16638.32914.509773.486468@grasshopper.cs.duke.edu> Content-Type: text/plain Message-Id: <1090421941.7114.26.camel@builder02.qubesoft.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Wed, 21 Jul 2004 15:59:01 +0100 Content-Transfer-Encoding: 7bit X-Virus-Scanned: ClamAV version 'clamd / ClamAV version 0.65', clamav-milter version '0.60p' cc: simokawa@freebsd.org cc: freebsd-current@freebsd.org Subject: Re: Excellent job on the firewire support! X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Jul 2004 14:59:10 -0000 On Wed, 2004-07-21 at 15:41, Andrew Gallatin wrote: > Doug Rabson writes: > > Actually thats the only downside of dcons. It doesn't cut in until the > > firewire controller attaches. It relies on the fact that the fwohci > > driver allows access to physical memory from any node on the bus > > (implemeted in hardware so you can examine the memory of a hung > > machine). The dconschat program uses this feature to access the dcons > > ring buffers in the target machine. > > Does remote access to physical memory require dcons to be loaded > on the target? No. The remote access to physical memory is a hardware-implemented feature of the firewire ohci hardware. Its enabled in fwohci_attach(). In the long term, I would like to restrict this a bit but right now all you have to have is fwohci loaded on the target machine. > > If no, assuming I had a Windows or Linux box on the firewire bus, would it be > possible to access physical memory from a different OS? Windows XP has some kind of firewire debug driver that you might have to load (I haven't read the docs on that). I don't think the linux driver enables physical access by default but it would be easy to hack it in (just write all ones to the right fwohci register).