[uClinux-dev] Re:Re: [uClinux-dev] question about Interrupt handler

JoeyShen shen_zl at 263.net
Mon Nov 19 03:10:51 EST 2001

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Thanks, Greg!
I think I know what you meant. But if I want to "tell" my applications the interrupt has occured, what can I do? Using FIFO, sending msg or some other kinds of IPCs?
Can interrupt handler creat a FIFO which would be read by process? 
Hm....maybe what I need is just polling.

>Hi Joey,
>JoeyShen wrote:
>>   Following Alessandro's book of device driver, I finally succeed in making the handler respond to the external interrupt. Thanks for Alessandro's great job!
>>   There still remains a question puzzled me. Alessandro said in the chapter of interrupt handling that "A handler can’t transfer data to or from user space". I wonder if the handler can send messages or signals to the user space applications. If it can not, I would wake up another kernel process which has slept on a certain signal, then the woken process would communicate with the user applications. Am I right?
>Yes. You cannot write to user space during an interrupt.
>Interrupts occur asynchronously to the running of applications.
>It is most likely the application that you want to write
>into won't be running when you get the interrupt.


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