Why Single Stepping Instruction on X86?

Question

So there is \"int 3\" which is an interrupt instruction used for breakpoints in debuggers.

But then there is also \"int 1\" which is used for single stepping. But wh

Answer 1

int 3 is used to set a breakpoint so that the code can execute freely until a particular point (the breakpoint) is reached. this speeds up the debugging process so it is not necessary to trap through known good code.

int 1 is used to unconditionally halt after every instruction. this can be handy when conditional branch instructions are executed and the condition of the status flags is not known. otherwise, a breakpoint would need to be set at branch address and the address of the instruction following the branch.

int 1 is can also be used at board bring-up when both the board hardware and the bring-up are new and untested.