interrupt-handling | 易学教程

printk inside an interrupt handler , is it really that bad?

阅读更多关于 printk inside an interrupt handler , is it really that bad?

问题 everybody knows that interrupt handler should be short as possible. and adding functions like printk for debugging inside an interrupt handler is something that shouldn't be done. Actually, I tried it before when I was debugging the linux kernel for an interrupt driven char device I written, and it wrecked the timing of the driver. The question I have, is why this is happening ? printk function is buffered ! it means, as far as I understand that the data is inserted in to a queue, and it's

what is meant by disabling interrupts?

阅读更多关于 what is meant by disabling interrupts?

When entering an inteerupt handler, we first "disable interrupts" on that cpu(using something like the cli instruction on x86). During the time that interrupts are disabled, assume say the user pressed the letter 'a' on the keyboard that would usually cause an interrupt. But since interrupts are disabled, does that mean that: the interrupt handler for 'a' would never be invoked, since interrupts are disabled in the critical section or the interrupt will be handled by the os but delayed, until interrupts are enabled again. Specifically, will the user need to press 'a' again, if the first time

How to trap ERR when using 'set -e' in Bash

阅读更多关于 How to trap ERR when using 'set -e' in Bash

问题 I have a simple script : #!/bin/bash set -e trap "echo BOO!" ERR function func(){ ls /root/ } func I would like to trap ERR if my script fails (as it will here b/c I do not have the permissions to look into /root). However, when using set -e it is not trapped. Without set -e ERR is trapped. According to the bash man page, for set -e : ... A trap on ERR, if set, is executed before the shell exits. ... Why isn't my trap executed? From the man page it seems like it should. 回答1: chepner's answer

Interrupts, Instruction Pointer, and Instruction Queue in 8086

阅读更多关于 Interrupts, Instruction Pointer, and Instruction Queue in 8086

Suppose an external interrupt request is made to 8086. Processor will handle the interrupt after completing the current instruction being executed (if any). Before handling of the interrupt, the state of the program will also be saved (PSW flag, registers etc.) by pushing data onto the stack segment. Now, most tutorials/documents describe that instruction pointer is also pushed onto the stack segment, which is okay because it was pointing to the next byte of instruction in the code segment (just before interrupt request was made). But what happens to the instruction queue? Is it also pushed

Detecting the type of iPhone interrupt

阅读更多关于 Detecting the type of iPhone interrupt

I can detect that the iPhone went to sleep and came back from sleep, by using the applicationWillResignActive and applicationDidBecomeActive. But how do I find out what kind of interrupt it was. I am making an audio player application, and need to keep the audio playing when the iPhone goes to sleep (which I know how to do). But I need to interrupt the audio when a message, alarm or low battery interrupt occurs. Also I need to resume the audio when the event is over. So how do I differentiate between these different interrupts. benzado That information is probably not available to your app,

How can we detect call interruption in our iphone application? [closed]

阅读更多关于 How can we detect call interruption in our iphone application? [closed]

问题 I need to detect incoming call interruption in my application. When application is in active state and there is any incoming call or SMS, my application grab the calling number in case if call and all details in case of SMS. I want to store these in my application. Is this possible to detect Call interruption and incoming SMS alert in our iPhone application? 回答1: You will have to use CoreTelephony Framework You can get information about the state of the call by using the CTCall class. the

Future.cancel() method is not working

阅读更多关于 Future.cancel() method is not working

问题 The code that I have creates a Callable instance and using ExecutorService a new thread is being created. I want to kill this thread after certain amount of time if the thread is not done with its execution. After going through the jdk documentation I've realized that Future.cancel() method can be used to stop the execution of the thread, but to my dismay its not working. Of course future.get() method is sending an interrupt to the Thread after the stipulated time (in my case its 2 seconds)

Uninterruptable process in Windows(or Linux)?

阅读更多关于 Uninterruptable process in Windows(or Linux)?

Is there any way to make a program that cannot be interrupted (an uninterrupted program)? By that, I mean a process that can't be terminated by any signal, kill command, or any other key combinations in any System: Linux, windows etc. First, I am interested to know whether it's possible or not. And if yes, upto what extend it is possible? I mostly write code in C, C++, and python; but I don't know any of such command(s) available in these programming languages. Is it possible with assembly language, & how ? Or in high level language c with embedded assembly code(inline assembly)? I know some

what is meant by disabling interrupts?

阅读更多关于 what is meant by disabling interrupts?

问题 When entering an inteerupt handler, we first "disable interrupts" on that cpu(using something like the cli instruction on x86). During the time that interrupts are disabled, assume say the user pressed the letter 'a' on the keyboard that would usually cause an interrupt. But since interrupts are disabled, does that mean that: the interrupt handler for 'a' would never be invoked, since interrupts are disabled in the critical section or the interrupt will be handled by the os but delayed, until

Interrupts, Instruction Pointer, and Instruction Queue in 8086

阅读更多关于 Interrupts, Instruction Pointer, and Instruction Queue in 8086

问题 Suppose an external interrupt request is made to 8086. Processor will handle the interrupt after completing the current instruction being executed (if any). Before handling of the interrupt, the state of the program will also be saved (PSW flag, registers etc.) by pushing data onto the stack segment. Now, most tutorials/documents describe that instruction pointer is also pushed onto the stack segment, which is okay because it was pointing to the next byte of instruction in the code segment