Tuesday, July 8, 2003

For anyone testing hardware, kernels, drivers, or beta systems, it is useful to return OS X to the old behavior when the kernel panics. That is, to fill the screen full o' gobbledy-gook that gives an indication as to what the system was doing when things went horribly, horribly wrong.

Turns out that it is quite easy to do so. Just go to a Terminal and issue:

sudo nvram boot-args="debug=0x100"

If you also want the system to boot in verbose mode, do:

sudo nvram boot-args="-v"

In theory, both can be enabled by:

sudo nvram boot-args="-v debug=0x100"

You can also disable one (or both!!) of the CPUs in dual CPU systems as documented in this tech note. That article also has links to a number of other interesting Open Firmware articles.

Of course, if you completely hose your NVRAM settings such that your system will no longer boot, you'll need to know the vulcan CPU pinch to reset the NVRAM settings. Power off the system and hold down cmd-opt-n-v (all keys at once!!) when powering up the machine. This is the same as entering "reset-all" at the open firmware prompt (which can be found by holding down cmd-opt-o-f when powering up the machine).

Magical Macintosh Key Sequences contains the most comprehensive list of keys I have found. It also contains a bunch of links to other useful chunks of information.
11:58:47 AM  pontificate