LinuxHPC.org/Cluster Builder 1.3

GNU Debugger

The GNU Debugger, usually called just GDB, is the standard debugger for the GNU software system. It is a portable debugger that runs on many Unix-like systems and works for many programming languages, including C, C++, and FORTRAN.
Technical details

Features

GDB offers facilities for tracing and altering the execution of computer programs. The user can monitor and modify the values of programs' internal variables, and call functions independently of the program's normal behavior.

GDB target processors (as of 2003) include: Alpha, ARM, H8/300, System/370, System 390, X86 and X86-64, IA-64 "Itanium", Motorola 68000, MIPS,PA-RISC, PowerPC, SuperH, SPARC, VAX.

Lesser-known target processors supported in the standard release have included A29K, ARC, AVR, CRIS, D10V, D30V, FR-30, FR-V, Intel i960, M32R, 68HC11, Motorola 88000, MCORE, MN10200, MN10300, NS32K, Stormy16, V850, VAX, and Z8000. (Newer releases will likely not include some of these.)

GDB has compiled-in simulators for target processors and also for lesser-known target processors such like M32R or V850.

Remote debugging

GDB offers a 'remote' mode often used when debugging embedded systems. Remote operation is when GDB runs on one machine and the program being debugged runs on another. GDB can communicate to the remote 'stub' which understands GDB protocol via Serial or TCP/IP.

The same mode is also used by KGDB for debugging a running linux kernel on the source level with gdb. With kgdb, kernel developers can debug a kernel similar to application programs. It makes it possible to place breakpoints in kernel code, step through the code and observe variables. On some architectures, where hardware debugging registers are available, also watchpoints can be set which trigger a breakpoint when a certain memory address is executed or accessed. kgdb requires an additional machine which is connected to the machine to be debugged using a serial cable or ethernet. On FreeBSD, also debugging using Firewire DMA is possible.

Limitations

The debugger does not contain its own graphical user interface, and defaults to a command-line interface. Several front-ends have been built for it, such as DDD, GDBtk/Insight and the "GUD mode" in Emacs. These offer facilities similar to debuggers found in integrated development environments.

Some other debugging tools have been designed to work with GDB, such as memory leak detectors.

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available under the GNU Free Documentation License. It uses material from
the Wikipedia article "GNU Debugger".}}