interrupt-handling

问题 I am having doubts, why exactly we need interrupt context? Everything tells what are the properties but no one explains why we come up with this concept? Another doubt related to same concept is, If we are not disabling the interrupt in interrupt handler, then what is the use of running this interrupt handler code in interrupt context ? 回答1: Why do we need Interrupt context? First, what do we mean by interrupt context ? A context is usually a state. There are two separate concepts of state.

问题 ftrace is used for function tracing of kernel. Now how does it work for interrupts. Can it track kernel functions in interrupt mode. If so can you explain how it works. I am trying to write a function that tracks function calls and it works fine in Supervisor mode but does not work in interrupt mode (goes into loop). I need to make it work in IRQ mode. 回答1: As in Linux kernel ARM exception stack init details, the amount of IRQ stack used by Linux is minimal. ARM has several banked registers

问题 I wanted to know when the processor get's interrupted and an ISR (interrupt service routine) is executed, is that executed in the context of the thread that was interrupted to handle this interrupt or is it executed in its own thread and then goes back to where it left of in the original thread? So a context switch actually occurs when an interrupt occurs? 回答1: A thread isn't created to handle the interrupt (part of why system calls can sometimes fail), though you can have a special thread to

问题 The wikipedia entry states: In computer system programming, an interrupt handler, also known as an interrupt service routine or ISR, is a callback function in microcontroller firmware, an operating system or a device driver, whose execution is triggered by the reception of an interrupt. How is ISR a callback. Is it the PC value stored on stack itself is the callback function? I.e., the ISR calls the interrupted function back. Hence the interrupted function is a callback. 回答1: A bit of setup

问题 I want to avoid nested interrupts at the interrupts entry in a CortexM based microcontroller. To achieve this I have an assembly file containing interrupt vectors and first instruction of each vector is the instruction ( CPSID I ) to disable interrupts globally. After every individual interrupt handler(written in C), execution returns to a common assembly routine which re-enables the interrupts with instruction CPSIE I and return from Interrupt/Exception process is triggered with instruction

问题 I am working on a project where i am trying to figure out how an interrupt is processed in the Global interrupt controller for a ARM architecture. I am working with pl390 interrupt controller. I see there is a line which is mentioned as legacy interrupts which bypasses the distributor logic. It is given that 2 interrupts can be programmed as a legacy interrupt. Can any one help with some explanation of what exactly is a legacy interrupt?. I trying searching online without any luck. 回答1:

问题 Can I call interrupt from within interrupt service routine in freestanding x686 environment? So can one do the following: isr: pusha call doSomething int 21h popa iret If it's possible, then do these nested interrupts have any significant cave ins? 回答1: An interrupt call is just analogous to a regular call with flags pushed. And what iret does is it returns and pops the flags. So, yes, interrupts can be called recursively. Actually calling an interrupt in another interrupt handler happens all

问题 I am toggling the input into a GPIO line on my BeagleBone from high to low every 500 ms using an Atmel uC. I have registered a handler for this in my Linux Kernel Module, but the handler is not being called for some reason. My module code is - #define GPIO 54 #define GPIO_INT_NAME "gpio_int" #define GPIO_HIGH gpio_get_value(GPIO) #define GPIO_LOW (gpio_get_value(GPIO) == 0) short int irq_any_gpio = 0; int count =0; enum { falling, rising } type; static irqreturn_t r_irq_handler(int irq, void

问题 I'm trying to write a linux kernel module which waits for a hardware trigger and then moves some data to an external memory via DMA. I've got the hardware trigger recognized in my kernel module, now I need to make it perform the DMA. The problem is that the function that performs the DMA involves a point where it sleeps until the DMA is completed. This isn't allowed in interrupts, so I can't call the function directly in my interrupt service routine. Is there a way I can set some kind of

问题 I've turned to state pattern for my netmf project. Something based on this: http://www.dofactory.com/Patterns/PatternState.aspx#_self2 I have a rotary encoder knob that will act differently in each state. I've been trying to wrap my head around this and can't get anything to work on my end. I'm not sure where and how to inject the interrupt handler into each state and how to invoke the switch of the interrupt handler. Without the State Pattern the code looks something like: RotaryEncoder RE =