Kernel dumps [was Re: possible changes from Panzura]

Jordan Hubbard jkh at mail.turbofuzz.com
Wed Jul 10 21:50:52 UTC 2013


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?

Absolutely.  In fact, before the advent of remote network debugging, FW was totally the debugging method of choice since firewire target DMA lets you do all kinds of useful things (as well as a few things that simply scare the security guys to death ;-) ).

My point was more that actually being able to debug a machine over the network is such a step up in terms of convenience/awesomeness that if anyone is thinking of putting any time and attention into this area at all, that's definitely the target to go for.

Looking at http://www.opensource.apple.com/tarballs/xnu/xnu-2050.22.13.tar.gz there's even reasonable "documentation" on the kernel debugging protocol in xnu/osfmk/kdp.  Folks could do worse than try to clone it.  The gdb debugger macros in support of it are also in xnu/kgmacros.  None of it is going to be 'drop in' for FreeBSD by any stretch of the imagination, but it's always easier to get to a destination when you have a map. :-)    Anyone with a Mac can also ""nvram boot-args="debug=0x144"" and test-drive it around, just to see how it works in actual practice.  See also:  https://developer.apple.com/library/mac/#documentation/Darwin/Conceptual/KEXTConcept/KEXTConceptDebugger/debug_tutorial.html

- Jordan




More information about the freebsd-hackers mailing list