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[[!meta copyright="Copyright © 2013 Free Software Foundation, Inc."]]

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[[!meta title="Help, I've just gotten a db> prompt"]]

If you see a `db>` prompt on the console, something unexpected and bad happened
inside the [[GNU Mach kernel|microkernel/mach/gnumach]], which it cannot
recover from.  (Think of it as the equivalent of a [[!wikipedia
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:

    0x8007cf1(8088488,5e,40000008,2aa008,0)
    0x80071bc(0,0,0,0,0)
    0x8006831(24fe00,2000,b,800,0)

This can be decyphered by using:

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

You can then [[send us|contact_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|microkernel/mach/gnumach/debugging]] is available.