Revision 74807afd3f4eb403e490b5db7af1ece117262f5b authored by Linus Torvalds on 27 September 2014, 21:42:18 UTC, committed by Linus Torvalds on 27 September 2014, 21:42:18 UTC
Pull MIPS fixes from Ralf Baechle: "The final round of fixes. One corner case in the math emulator and another one in the mcount function for ftrace" * 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: MIPS: mcount: Adjust stack pointer for static trace in MIPS32 MIPS: Fix MFC1 & MFHC1 emulation for 64-bit MIPS systems
IRQ.txt
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.
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