中断函数和printk()

[yongyuan10cn]

1，中断处理函数的返回值和形参类型都必须是void吗？
2，printk()函数是内核的打印，可以在终端上打印出来吗？
谢谢！

[jiangyue009]

printk的信息可以在终端显示

[yongyuan10cn]

那关于中断函数的呢，继续请教

[joyself]

看看 2.4和 2.6的内核的request_irq原型就知道了。

2.4：
int request_irq(unsigned int irq,
void (*handler)(int, void *, struct pt_regs *),
unsigned long flags,
const char *dev_name,
void *dev_id);

2.6：
int request_irq(unsigned int irq,
irqreturn_t (*handler)(int, void *, struct pt_regs *),
unsigned long flags,
const char *dev_name,
void *dev_id);

下面是LDD3（2.6kernel）上摘录下来的：

Interrupt handlers should return a value indicating whether there was actually an interrupt to handle. If the handler found that its device did, indeed, need attention, it should return IRQ_HANDLED; otherwise the return value should be IRQ_NONE. You can also generate the return value with this macro:

IRQ_RETVAL(handled)
where handled is nonzero if you were able to handle the interrupt. The return value is used by the kernel to detect and suppress spurious interrupts. If your device gives you no way to tell whether it really interrupted, you should return IRQ_HANDLED.