Re: interrupts

[Manu Anand <manu.anand@xxxxxxxxx>]

On 9/20/05, raja <vnagaraju@xxxxxxxxxxxx> wrote:

actually i am writing a module to sense the timer interrupt.
Any way for every clock tick the timer updates the system time.I want to
find out the process's information that was running at the time the
timer interrupt occures.

Hi Raja:

Am I write in assuming that u want ur module to sort of hook on to timer interrupt? The idea being that ur module should also be invoked when the timer interrupt handler is invoked.

In that case, the approach you've followed will not work. Timer interrupt is not shared.

When the kernel receives the interrupt, it invokes sequentially each reqistered handler on the line. However in your case the call

request_irq(TIMER_INTERRUPT, timer_interrupt_handler,SA_SHIRQ,DEVICE_NAME,&devNo);

will fail since the IRQ line is already registered for timer interrupt in an exclusive non-shared( specified using SA_INTERRUPT

// Check out http://lxr.linux.no/source/arch/i386/mach-default/setup.c#L74
static struct 
irqaction irq0  = 
{ timer_interrupt, SA_INTERRUPT, 
CPU_MASK_NONE, "timer", NULL, NULL};

Your approach is valid for interrupts specified with SA_SHIRQ flag.


Manu

 

I have registered my handler that prints simply a message when ever the
timer interrupt occures.But it is not working.It is not printing any
message.

I am listing my code below.Will you please help me









#ifndef __KERNEL__
        #define __KERNEL__
#endif

#ifndef MODULE
        #define MODULE
#endif

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/interrupt.h>

MODULE_AUTHOR("RAJA");
MODULE_DESCRIPTION("TIMER INTERRUPT");
MODULE_LICENSE("GPL");

#define DEVICE_NAME "timer_interrupt"
#define TIMER_INTERRUPT 0
static int __init init_timer_interrupt(void);
static void __exit exit_timer_interrupt(void);

static irqreturn_t timer_interrupt_handler(unsigned int,void *, struct
pt_regs *);

int devNo;
struct file_operations fops = {};

static irqreturn_t timer_interrupt_handler(unsigned int irq,void *data,
struct pt_regs *regs)
{
        printk("Timer Interrupt Occured\n");
        return 0;
}

static int __init init_timer_interrupt()
{
        printk("Entered Into init_timer\n");
        devNo = register_chrdev(0,DEVICE_NAME,&fops);

request_irq(TIMER_INTERRUPT,timer_interrupt_handler,SA_SHIRQ,DEVICE_NAME,&devNo);
        printk("Exited From init_timer\n");
        return 0;
}

static void __exit exit_timer_interrupt()
{
        printk("Entered Into exit_timer\n");
        unregister_chrdev(devNo,DEVICE_NAME);
        free_irq(TIMER_INTERRUPT,&devNo);
        printk("Exited From exit_timer\n");
}

module_init(init_timer_interrupt);
module_exit(exit_timer_interrupt);














On Tue, 2005-09-20 at 17:02 +0500, Fawad Lateef wrote:
> On 9/20/05, raja < vnagaraju@xxxxxxxxxxxx> wrote:
> > yaa.
> > I have checked /proc/interrupts.
> > But there it is given the interrupt numbers.
> >
> > actually the requirement is i am writing a module that it senses when
> > ever the interrupt occures and prints the interrupt number.
> >
> > Will you please help me.
> >
> >
>
> What sort of module you are writing ?? How you are going to sense
> interrupts when they occurs ?? I think for getting signal through the
> call-backed function from the kernel you have to register your
> interrupt handlers, so that you can be notified by the kernel ........
>
> Or hack into the kernel, to get notified for each interrupt, but AFAIK
> your module can't get every single interrupt until you register them
> with the kernel ........
>
> Correct me if I m wrong !!!!
>
>


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