Date: Wed, 21 Jul 2004 15:59:01 +0100 From: Doug Rabson <dfr@nlsystems.com> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: freebsd-current@freebsd.org Subject: Re: Excellent job on the firewire support! Message-ID: <1090421941.7114.26.camel@builder02.qubesoft.com> 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>
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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).home | help
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