[repiret]

>> processors such as the ARM cortex-M series have built in debug features such as ~8 breakpoint registers

> And these software breakpoints are written into flash.

The GP is referring to the eight FPB hardware breakpoints, which do not need to be written to flash. Most Cortex-M have an additional four hardware breakpoints from the DWT. You can get a lot done with 12 breakpoints before you need to start writing things to flash.

More generally, as long as the debug interface allows you to run with interrupts disabled and has at least one HWBP, you can single-step without writing SWBP to memory.