23 lines
962 B
Plaintext
23 lines
962 B
Plaintext
What is an IRQ?
|
|
|
|
An IRQ is an interrupt request from a device.
|
|
Currently they can come in over a pin, or over a packet.
|
|
Several devices may be connected to the same pin thus
|
|
sharing an IRQ.
|
|
|
|
An IRQ number is a kernel identifier used to talk about a hardware
|
|
interrupt source. Typically this is an index into the global irq_desc
|
|
array, but except for what linux/interrupt.h implements the details
|
|
are architecture specific.
|
|
|
|
An IRQ number is an enumeration of the possible interrupt sources on a
|
|
machine. Typically what is enumerated is the number of input pins on
|
|
all of the interrupt controller in the system. In the case of ISA
|
|
what is enumerated are the 16 input pins on the two i8259 interrupt
|
|
controllers.
|
|
|
|
Architectures can assign additional meaning to the IRQ numbers, and
|
|
are encouraged to in the case where there is any manual configuration
|
|
of the hardware involved. The ISA IRQs are a classic example of
|
|
assigning this kind of additional meaning.
|