Writing Custom Command in FreeBSD's DDB Kernel Debugger

John Baldwin

FreeBSD’s kernel includes an in-kernel debugger (DDB) inherited from 4BSD. DDB’s command interface provides limited capabilities for examining data, but new commands can be added relatively easily to add pretty-printing of data structures. This talk goes over the basic APIs available to DDB command handlers and how to register handlers as new commands. It will also cover more advanced topics such as manually parsing DDB commands to support richer command arguments.

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