>
> Second, RF_SHAREABLE should generally never be used. There's one
> exception. That's for interrupts that can be shared in the hardware.
Actually, this is almost exactly the wrong way up; RF_SHAREABLE should
always be used unless you know that the interrupt _can't_ be shared.
In many cases, the driver can't tell whether it's allocating an interrupt
which is or isn't shareable, and the only code that _can_ make this
determination is in the parent layers. ie. as this request propagates
upwards, the parent bus(ses) code should remove the flag in cases where
it's know the interrupt can't be shared.
> PCI bus is the only bus that does this reliably. Since the PCCARD bus
> can be bridged to the ISA bus or to PCI bus, you can't reliably share
> interrupts there.
... and this is why. The pccard/cardbus bridge code, or the parent bus
code, needs to decide whether the interrupt is or is not shareable - not
the driver.
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