Contents
How interrupts are enabled and disabled?
The processor services interrupts and exceptions only between the end of one instruction and the beginning of the next. When the repeat prefix is used to repeat a string instruction, interrupts and exceptions may occur between repetitions.
What are the steps involved in servicing an interrupt?
Servicing an interrupt consists of two, and sometimes three, steps:
- Saving volatile information (such as register contents) quickly, in an interrupt service routine that runs at IRQL = DIRQL.
- Processing the saved volatile information in a deferred procedure call (DPC) that runs at IRQL = DISPATCH_LEVEL.
How are interrupts disabled?
Mutual Exclusion via Interrupt Control Disabling interrupts is one approach. The programmer can disable interrupts prior to entering the critical section, and then enable interrupts after leaving the critical section: enable_interrupts();
What is the function of interrupt service procedure?
An interrupt service routine (ISR) is a software routine that hardware invokes in response to an interrupt. ISR examines an interrupt and determines how to handle it executes the handling, and then returns a logical interrupt value. If no further handling is required the ISR notifies the kernel with a return value.
How do I clear an interrupt flag?
The flag may be set or cleared using the CLI (Clear Interrupts), STI (Set Interrupts) and POPF (Pop Flags) instructions. CLI clears IF (sets to 0), while STI sets IF to 1. POPF pops 16 bits off the stack into the FLAGS register, which means IF will be set or cleared based on the ninth bit on the top of the stack.
What type of interrupt can be disabled?
Difference between maskable and nonmaskable interrupt :
| SR.NO. | Maskable Interrupt |
|---|---|
| 1 | Maskable interrupt is a hardware Interrupt that can be disabled or ignored by the instructions of CPU. |
| 2 | When maskable interrupt occur, it can be handled after executing the current instruction. |
Why interrupt service routine is used?