Re: device driver / char module interrupt vector -> user space code

From: Alan Cox (alan@lxorguk.ukuu.org.uk)
Date: Fri Aug 09 2002 - 05:34:00 EST


On Fri, 2002-08-09 at 09:49, SA wrote:
> I am writing a char module for a PCI stage controller and want to add the
> following functionality;
>
> The device will generate an interrupt (or software trigger) and I want this to
> run a bit of user code with relatively latency. (<1ms). I am unclear how to
> do this while still separating the user from the kernel code and maintaining
> security - would this usually be handled by issuing a signal to the user space
> process? if so how and what latency can I expect?

You could deliver a signal, or if appropriate you can have a system call
that blocks until the IRQ. To get good reliable latency, mlockall() the
process you need to be real time, and set it to a real time scheduling
priority.

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