What is a trap instruction? Explain its use in operating systems.
Answers
Answer:
A trap instruction is a procedure call that synchronously transfers the control. It is a software interrupt generated by the user program or by an error when the operating system is needed by it to perform the system calls or an operation.
Thus, a trap instruction used to switch from the user mode of the system to the kernel mode.
Answer:
A trap is an exception in a user process. It's caused by division by zero or invalid memory access. It's also the usual way to invoke a kernel routine (a system call) because of those run with a higher priority than user code. Handling is synchronous (so the user code is suspended and continues afterward). In a sense they are "active" - most of the time, the code expects the trap to happen and relies on this fact.
Explanation: