On Wed, 13 Dec 2006, Jan Engelhardt wrote:
>
> For the sharing case, some sort of softirq should be created. That is, when a
> hard interrupt is generated and the irq handler is executed, set a flag that at
> some other point in time, the irq is delivered to userspace. Like you do with
> signals in userspace:
NO.
The whole point is, YOU CANNOT DO THIS.
You need to shut the device up. Otherwise it keeps screaming.
Please, people, don't confuse the issue any further. A hardware driver
ABSOLUTELY POSITIVELY HAS TO
have an in-kernel irq handler that knows how to turn the irq off.
End of story. No ifs, buts, maybes about it.
You cannot have a generic kernel driver that doesn't know about the
low-level hardware (not with current hardware - you could make the "shut
the f*ck up" a generic thing if you designed hardware properly, but that
simply does not exist in general right now).
In short: a user-space device driver has exactly TWO choices:
- don't use interrupts at all, just polling
- have an in-kernel irq handler that at a minimum knows how to test
whether the irq came from that device and knows how to shut it up.
This means NOT A GENERIC DRIVER. That simply isn't an option on the
table, no matter how much people would like it to be.
Linus
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