Kernel debugger

A kernel debugger is a debugger present in some operating system kernels to ease debugging and kernel development by the kernel developers. A kernel debugger might be a stub implementing low-level operations, with a full-blown debugger such as GNU Debugger (gdb), running on another machine, sending commands to the stub over a serial line or a network connection, or it might provide a command line that can be used directly on the machine being debugged.

Operating systems and operating system kernels that contain a kernel debugger:

• The Windows NT family includes a kernel debugger named KD,^[1] which can act as a local debugger with limited capabilities (reading and writing kernel memory, and setting breakpoints)^[2] and can attach to a remote machine over a serial line, IEEE 1394 connection, USB 2.0 or USB 3.0 connection.^[3] The WinDbg GUI debugger can also be used to debug kernels on local and remote machines.
• BeOS and Haiku include a kernel debugger usable with either an on-screen console or over a serial line. It features various commands to inspect memory, threads, and other kernel structures. In Haiku, the debugger is called "Kernel Debugging Land" (KDL).^[4]
• DragonFly BSD
• Linux kernel; No kernel debugger was included in the mainline Linux tree prior to version 2.6.26-rc1 because Linus Torvalds didn't want a kernel debugger in the kernel.^[5][6]
  • KDB (local)^[7]
  • KGDB (remote)
  • MDB (local/remote)^[8][9][10]
• NetBSD has DDB for local and KGDB for remote.
• macOS has ddb for local and kdp for remote.^[11]
• OpenBSD includes ddb which has a syntax is similar to GNU Debugger.^[12]