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

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

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.