If hardware watchpoints are supported (the default assumption in GDB), then the setting and clearing of watchpoints is very similar to breakpoints, but using z2 and Z2 packets (for write watchpoints), z3 and Z3 packets (for read watchpoints) and z4 and Z4 packets (for access watchpoints)

GDB also supports software write watchpoints. These are implemented by single stepping the target, and examining the watched value after each step. This is painfully slow when GDB is running native. Under RSP, where each step involves an number of packet exchanges, the performance drops ever further. Software watchpointing should be restricted to the shortest section of code possible.