devices hooked up to the HPI pin.
HPIs cannot be masked at the interrupt controller; they can only be masked
by disabling IRQs in the XScale core. To deal with this, we tweak the
interrupt frame so that IRQs are disabled when the interrupt dispatcher
returns due to a masked HPI interrupt. IRQs will be re-enabled by a
subsequent splx(9).
Fortunately the only instance where HPI is used is for the console UART
on a couple of boards, so this hack does not adversely affect performance.
Contributed by Wasabi Systems.
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