我用cortex-A9开发板做了一些实验。我使用gpio_to_irq（）来获取一个irq
num，然后我请求了irq并编写了一个小驱动程序，在syslog中为196。我在asm_do_IRQ中添加了一些printks。当我触发gpio中断时，驱动程序工作正常，但是asm_do_IRQ中的irq
num是62。我不明白。为什么irq号码与我要求的号码不同？驱动程序如下：

    #include <linux/module.h>
    #include <linux/interrupt.h>
    #include <linux/irq.h>
    #include <linux/gpio.h>

    #define GPIO_N 36     //gpio number

    int flag = 0;

    static irqreturn_t handler(int irq,void *dev_id)
    {
            printk("hello world hahahahahhahahah \n\n");
            return 0;
    }

    static int __init gpio_test_init(void)
    {
            if(gpio_request_one(GPIO_N,GPIOF_DIR_IN,"some test")<0)
            {
                    printk(KERN_ERR "Oops! BAD! BAD! BAD!\n\n");
                    return 0;
            }

            int irq,irq2;
            irq = OMAP_GPIO_IRQ(TEST_GPIO);
            printk("irq : %d \n",irq,irq2);
            // ..................
            // irq : 196 in dmesg 
            //......................
            set_irq_type(irq,IRQ_TYPE_EDGE_FALLING);
            enable_irq(gpio_to_irq(GPIO_N));
            int err;
            // request the irq ...
            if((err = request_irq(irq,&handler,0,NULL,NULL))<0)
            {
                    printk("err : %d\n",err);
                    return 0;
            }
            printk("gpio test init success!\n");
            flag = 1;
            return 0;
    }
    static void __exit gpio_test_exit(void)
    {
            int irq = gpio_to_irq(TEST_GPIO);
            if(flag == 1)free_irq(irq,NULL);
            gpio_free(TEST_GPIO);
            printk("gpio test exit byebye!\n");
    }

    module_init(gpio_test_init);
    module_exit(gpio_test_exit);
    MODULE_LICENSE("GPL");

在arch / arm / kernel / irq.c中的asm_do_IRQ

    asmlinkage void __exception_irq_entry
    asm_do_IRQ(unsigned int irq, struct pt_regs *regs)
    {
            struct pt_regs *old_regs = set_irq_regs(regs);
            printk("the irq : %d\n",irq);  
            //............... 
            // I get 62 here
            //...............
            irq_enter();

            /*
             * Some hardware gives randomly wrong interrupts.  Rather
             * than crashing, do something sensible.
             */
            if (unlikely(irq >= nr_irqs)) {
                    if (printk_ratelimit())
                            printk(KERN_WARNING "Bad IRQ%u\n", irq);
                    ack_bad_irq(irq);
            } else {
                    generic_handle_irq(irq);
            }

            /* AT91 specific workaround */
            irq_finish(irq);

            irq_exit();

            set_irq_regs(old_regs);

    }