With STM32 ST-LINK after Taregt -> Option bytes
nBoot0_SW_Cfg -
Cheked: The BOOT0 is bonded to GPIO pin (PB8 for small packages, PF11 for big packages)
Uncheked: Its allows user to disable BOOT0 pin completely and use User Option bit ( nBoot0 ).
If nBOOT0 is cheked (=1) Main Flash memory is selected as boot area.
Table from reference manual
