Editing GNU Debugger (section)

===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" that understands GDB protocol through a serial device or TCP/IP.<ref>{{cite web|url=http://www.embecosm.com/appnotes/ean4/embecosm-howto-rsp-server-ean4-issue-2.pdf|title=Howto: GDB Remote Serial Protocol: Writing a RSP Server}}</ref> A stub program can be created by linking to the appropriate stub files provided with GDB, which implement the target side of the communication protocol.<ref>{{cite web|url=http://davis.lbl.gov/Manuals/GDB/gdb_17.html#SEC140|title=Implementing a remote stub}}</ref> Alternatively, [[gdbserver]] can be used to remotely debug the program without needing to change it in any way.

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 in much the same way as they debug application programs. It makes it possible to place breakpoints in kernel code, step through the code, and observe variables. On architectures where hardware debugging registers are available, watchpoints can be set which trigger breakpoints when specified memory addresses are 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]], it is also possible to debug using [[FireWire]] [[direct memory access]] (DMA).<ref>{{cite web|url=http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug-dcons.html|title=Kernel debugging with Dcons}}</ref>