When I was reading some OpenDarwin docs on how to debug the kernel, I discovered that there are these wonderful
kprintf statements in the kernel that you can turn on with a simple debug option. Unfortunately, those get printed to a serial port, which I don’t have on my PowerBook. I found a really simple way around this, for doing some simple debugging.
I modified the
bsd/sys/systm.h file, where the prototype for
kprintf lives. I simply commented out the definition for
kprintf and put in a
#define that defined
kprintf to be the same as
You can enable the
printfs by putting
debug=0x02 on your boot arguments. Here’s how I do that:
sudo nvram boot-args='debug=0x02'
printf output will go to
Here’s my patch for systm.h.