Re: Excellent job on the firewire support!

From: Doug Rabson (dfr_at_nlsystems.com)
Date: 07/21/04

  • Next message: Daniel Lang: "Re: fetch hangs, part 2" 
    To: Andrew Gallatin <gallatin@cs.duke.edu>
Date: Wed, 21 Jul 2004 15:59:01 +0100

    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).

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  • Next message: Daniel Lang: "Re: fetch hangs, part 2"

    Relevant Pages

    • Re: Excellent job on the firewire support!
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