If you see a db> prompt on the console, something unexpected and bad happened inside the GNU Mach kernel, which it cannot recover from. (Think of it as the equivalent of a Linux kernel oops, for example.) The db> prompt is actually the GNU Mach kernel debugger waiting for your commands. For example, you can then reboot the system by issuing the reboot command, or if you want to help analyze the problem, start by typing in the trace command, which will display the function call trace leading to the crash:


This can be decyphered by using:

$ addr2line -i -f -e /boot/gnumach 0x8007cf1 0x80071bc 0x8006831

You can then send us the whole results of the trace and the addr2line commands, as well as the exact version of the GNU Mach kernel you were running, for further investigation. More information about the GNU Mach debugger is available.