Software interrupts are generally used to make system calls i.e.

A device generates a message-signaled interrupt by writing a data value to a particular address. The system supports two different types of ISRs: The driver can register an InterruptService routine to handle line-based or message-signaled interrupts. Types of interrupt. A trap, also known as a software interrupt, is an instruction that explicitly generates an exception condition.The most common use of a trap is to enter supervisor mode. It can receive any interrupt type, so the value of IP and CS will change on the interrupt type received. On a full sized arm this can be executed at the lower/est execution levels but is serviced by a higher more privileged mode or execution level. 3.3.3 Traps. What would happen if a lot of interrupts happened at the same time? Interrupt sources are of the following types: All interrupt sources have their own configurable priority and list of targeted Cortex-A9 processors, that is, a list of Cortex-A9 processors that the interrupt is sent to when triggered by the interrupt distributor. How does the CPU know which one to deal with first? ARM has one called swi software interrupt or svc. Interrupt generated by executing an instruction is called software interrupt. Software Interrupts: Software interrupt can also divided in to two types. So, an interrupt can stop the CPU from what it is doing and instead start it doing something else. Marilyn Wolf, in Computers as Components (Fourth Edition), 2017. All interrupt sources are identified by a unique ID. And like the number of soft interrupts in x86, this is for example so that an application can make a service call. 6. Interrupts are of different types like software and hardware, maskable and non-maskable, fixed and vector interrupts, and so on. Interrupt Service Routine (ISR) comes into the picture when interrupt occurs, and then tells the processor to take appropriate action for the interrupt, and after ISR execution, the controller jumps into the main program. o Non Maskable Interrupt: The hardware which cannot be delayed and should process by the processor immediately. 2. This interrupt can be masked or delayed. Software Interrupts The software interrupts are program instructions. The CPU knows which interrupt to handle first because there are a hierarchy of interrupts. o Maskable Interrupt: The hardware interrupts which can be delayed when a much highest priority interrupt has occurred to the processor. Windows Vista and later operating systems support both line-based and message-signaled interrupts.

Software Interrupts – These are instructions that are inserted within the program to generate interrupts. It is a level triggered interrupt. While running a program, if software interrupt instruction is encountered then the processor initiates an interrupt. The 8086 processor has 256 types of software interrupts. There are 256 software interrupts in 8086 microprocessor. These instructions are inserted at desired locations in a program. It's also called 'trap'.