How does a debugger like gdb work to set a breakpoint through JTAG?

Question

I am working on debugging with gdb. I wanted to know how gdb works internally to set the embedded processor's breakpoint via JTAG.

Answer 1

It either programs the hardware checkpoint register, or places the software checkpoint, replacing the instruction at the breakpoint with the instruction that will throw an exception.

Answer 2

For each processor everything is different, you need to find the jtag debugger details for the specific processor. Not only a processor family, but also a specific processor. Specification / user guides, if available, are usually available from the chip supplier or primary supplier, depending on the product.

Answer 3

Several times, when I used GDB with the JTAG module, GDB was passed through JTAG using the gdbserver program, which processed JTAG parts. For example, using the OpenOCD JOAG module: http://openocd.sourceforge.net/doc/html/GDB-and-OpenOCD.html

This essentially means that GDB does not know anything about the JTAG module - it relies on the gdbserver interface, and this server does everything it needs, behind the scenes, to do what GDB requests.