Interrupt Handling

[Henning Sudbrock]

Hi,

as far as I know there's the possiblity that certain Interrupt Requests
(IRQs) can be masked, either by hardware or by software.

Assume that some device requests an interrupt while the corresponding
Interrupt Line is masked. What happens then? Is the Interrupt Request
put into some sort of queue? Or is it just dropped and forgotten, so
that the device has to request an interrupt later again?

Does anyone know what happens in that case?

Thanks, Henning

 

[Bob]

as far as I know there's the possiblity that certain Interrupt Requests
(IRQs) can be masked, either by hardware or by software.

Assume that some device requests an interrupt while the corresponding
Interrupt Line is masked. What happens then? Is the Interrupt Request
put into some sort of queue? Or is it just dropped and forgotten, so
that the device has to request an interrupt later again?

Does anyone know what happens in that case?

Typically hardware interrupts are handled by a "priority interrupt
controller".

There are two common problems with interrupts:

1) The interrupt process takes too much time to execute before more
critical interrupts are executed. Sometimes that results in race
conditions.

2) As long as the interrupt flag is set, no other interrupts can be
executed. Failure to clear the flag results in critical interrupts
being held up.

Most of the crashes in Windows are caused by poor interrupt handling.