The preempt_rt kernel forces all irq interrupts to be threaded,
but special interrupts can be excluded from this conversion.
The cascade interrupt should be part of these exceptions.
In this case, irq2 is initialized before "kthreadd" task, which
converts irq interrupt to threaded.
If this irq is threaded, the kernel calls "try_to_wake_up" function
to wake up "kthreadd" task, but at that moment, "kthreadd" task
has no been initialize and try_to_wake_up wakes up a NULL task.
Signed-off-by: Liming Wang <liming.wang@windriver.com>
]
Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
