For example when my algorithm is driven by interrupts and "user code" need to do nothing. One approach is to use something like WFI instruction in the loop, but

For example when my algorithm is driven by interrupts and "user code" need to do nothing. One approach is to use something like WFI instruction in the loop, but this instruction has its own issues, for example I experienced issues with attached gdb on some chinese STM32 clones. Using busy loop worked just fine. Using "unused" volatile also works, but it incurs SRAM traffic, which might slow down DMA and cause other effects. So ideally it should be simple empty loop compiled to `b .` instruction (jump to itself). Another infinite loop usage is for abort() or exit() handler, as a crash place. For this use-case, using "unused" volatile does not cause issues, because device is already crashed, however it still feels wrong.