Kernel dumps [was Re: possible changes from Panzura]

[Bakul Shah]

On Wed, 10 Jul 2013 14:50:19 PDT Jordan Hubbard <jkh at mail.turbofuzz.com> wrote:
> 
> On Jul 10, 2013, at 1:04 PM, asomers at gmail.com wrote:
> 
> > I don't doubt that it would be useful to have an emergency network
> > stack.  But have you ever looked into debugging over firewire?
> 
> My point was more that actually being able to debug a machine over the networ
> k is such a step up in terms of convenience/awesomeness that if anyone is thi
> nking of putting any time and attention into this area at all, that's definit
> ely the target to go for.

You have to use this just once to see how convenient it is!

For a previous company James Da Silva did this in 1997 by
adding a network console (IIRC in a day or two).  A new
ethernet type was used + a host specific ethernet multicast
address so you could connect from any machine on the same
ethernet segment.  Either as a remote console for the usual
console IO & ddb, or to run remote gdb.  Quite insecure but
that didn't matter as this was used in a test network.  There
was no emegerency network stack; just a polling function added
to an ethernet driver since this had to work even when the
kernel was on the operating table under anaesthetic! No new
gdb hacks were necessary since the invoking program set things
up for it.

If I was doing this today, I'd probably still do the same and
make sure that the interface used for remote debugging is on
an isolated network.