Excellent job on the firewire support!

[Doug Rabson]

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).