This section describes two debuggers that can be applied to device drivers. Both debuggers are described in detail in the Oracle Solaris Modular Debugger Guide .
The kmdb(1) kernel debugger provides typical runtime debugger facilities, such as breakpoints, watch points, and single-stepping. The kmdb debugger supersedes kadb, which was available in previous releases. The commands that were previously available from kadb are used in kmdb, in addition to new functionality. Where kadb could only be loaded at boot time, kmdb can be loaded at any time. The kmdb debugger is preferred for live, interactive debugging due to its execution controls.
The mdb(1) modular debugger is more limited than kmdb as a real-time debugger, but mdb has rich facilities for postmortem debugging.
The kmdb and mdb debuggers mostly share the same user interface. Many debugging techniques therefore can be applied with the same commands in both tools. Both debuggers support macros, dcmds, and dmods. A dcmd (pronounced dee-command) is a routine in the debugger that can access any of the properties of the current target program. A dcmd can be dynamically loaded at runtime. A dmod, which is short for debugger module, is a package of dcmds that can be loaded to provide non-standard behavior.
Both mdb and kmdb are backward-compatible with legacy debuggers such as adb and kadb. The mdb debugger can execute all of the macros that are available to kmdb as well as any legacy user-defined macros for adb. See the Oracle Solaris Modular Debugger Guide for information about where to find standard macro sets.