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SubjectRe: raw memory & PCI bus access
pavel@rts.loniis.ru wrote:
>
> Hi all
>
> Say I have a driver that realizes a "virtual irq" (/dev/irq).

I think Pavel Machek may have already written something like this?


> User application waits for interrupts by calling select() for
> that device. Obviously such a driver doesn't need much of code.
> What a maximum latency between irq occurance and
> userapp reaction I should expect?

In modern machines it shouldn't be too bad -- but if you are concerned
about it, a better course may be to at least put your interrupt handler
in kernel space.

Another possibility is have your user space driver pass information to
/dev/irq, which tells the generic /dev/irq how to acknowledge
interrupts, read data into a buffer, and other simple operations like
that.

Jeff

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