How Debug Works in ST-Link?

[MLeff.1]

Hello, I'm researching the mechanisms of debugging in STM32F407 MCU using several debug probes. I previously used J-Link and I could see the details of the breakpoints in the FPB unit, but when I switched to ST-Link I couldn't see the details of the breakpoints, the registers were empty and the FPB wasn't even enabled. However the debug worked and the processor halted on each breakpoint. My question is, how breakpoints are set in ST-Link and where can I read them?

Thank you.

[Uwe Bonnes]

Loo at the relevant arm documents. debug_interface_v5_2_architecture_specification_IHI0031 is the fundamental debugging,  DDI0439C_cortex_m4 describes the cortex core. A look at the H7 reference manual in the debug chapter is also helpfull