[uClinux-dev] question about Interrupt handler

Greg Ungerer gerg at snapgear.com
Sun Nov 18 21:50:37 EST 2001


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.

Regards
Greg


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