How does the software trigger an interrupt?

Question

BlackTom AI · Accepted Answer

A software-triggered interrupt is invoked by executing a system call.

Relevant concepts: interrupts are events that transfer control from user code to the operating system to handle asynchronous events (hardware interrupts) or synchronous requests/exceptions (software interrupts). Software interrupts are generated by a special instruction or operation (e.g., the INT instruction on x86, or syscall/sysenter/syscall primitives) that causes a controlled trap into kernel mode, saving process context and jumping to an OS handler defined in the interrupt/exception vector table.

Step-by-step reasoning:
1. A user process needs an OS service (file I/O, process control, etc.). It cannot directly execute privileged operations, so it requests the kernel.
2. The process executes a special operation (system call). This can be implemented as a software interrupt/trap instruction (INT n) or via dedicated syscalls (syscall/sysenter) which generate a synchronous transfer to the kernel.
3. The CPU switches privilege level from user mode to kernel mode, saves the program counter and necessary registers onto the stack or process control block, and references the interrupt/exception vector to find the kernel entry point.
4. The OS kernel handler executes the requested service, using privileges to access hardware or protected resources.
5. Upon completion, the kernel restores the saved context and returns to user mode (via IRET/return-from-system-call), resuming the user process.

Why the correct answer is correct: "Executing a special operation called system call" accurately describes the standard mechanism for software-generated interrupts — a controlled trap to the kernel.

Why other options are incorrect:
- "Sending signals to CPU through bus": that describes hardware interrupts transmitted over physical buses, not software-triggered ones.
- "Executing a special program called interrupt trigger program" and "Executing a special program called system program": these imply separate user programs, but software interrupts are produced by executing a special instruction/operation (system call), not a distinct program.

Final confirmation: the correct answer is "Executing a special operation called system call."

How does the software trigger an interrupt?单项选择题

类似问题

If a process invokes the exec system call:

Which system call returns the process identifier of a child when it terminates?

Choose the incorrect statement about system calls.

Which system call returns the process identifier of a terminated child?

A system call is a request made by a program to the:

Question at position 8 A System call is a: Library function that uses user/ kernel stubs to carry out the service task by running its code in the kernel modePrivileged instruction that run in the kernel modeKernel function that my be called only within the kernelClear my selection

What is a system call?

Which of the following orderings is from fastest to slowest?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单