1) I didn't see anything that suggested that all DLL functions have this hot-patch point. I think from his perspective "Windows DLL" means "a DLL that is part

1) I didn't see anything that suggested that all DLL functions have this hot-patch point. I think from his perspective "Windows DLL" means "a DLL that is part of the Windows operating system", not "a DLL used by an application executing on Windows". 2) I think he addressed this - someone might be executing the function while you are trying to patch it. Having a 2-byte, one clock cycle NOP at the front means that you can replace it "atomically" from the perspective that nobody can walk into the middle of you updating the memory.