From: Eric W. Biederman <[email protected]> Signed-off-by: Eric W. Biederman <[email protected]> --- Documentation/IRQ.txt | 22 ++++++++++++++++++++++ 1 files changed, 22 insertions(+), 0 deletions(-) diff --git a/Documentation/IRQ.txt b/Documentation/IRQ.txt new file mode 100644 index 0000000..237235d --- /dev/null +++ b/Documentation/IRQ.txt @@ -0,0 +1,22 @@ +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. -- 1.4.0.gc07e - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
- References:
- [PATCH 0/25] Decouple IRQ issues (MSI, i386, x86_64, ia64)
- From: [email protected] (Eric W. Biederman)
- [PATCH 1/25] irq: Convert the move_irq flag from a 32bit word to a single bit
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 2/25] irq: Add moved_masked_irq
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 3/25] x86_64 irq: Reenable migrating irqs to other cpus.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 4/25] msi: Simplify msi enable and disable.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 5/25] msi: Make the msi boolean tests return either 0 or 1.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 6/25] msi: Implement helper functions read_msi_msg and write_msi_msg.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 7/25] msi: Refactor the msi_ops.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 8/25] msi: Simplify the msi irq limit policy.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 9/25] irq: Add a dynamic irq creation API
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 10/25] ia64 irq: Dynamic irq support
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 11/25] i386 irq: Dynamic irq support
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 12/25] x86_64 irq: Dynamic irq support
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 13/25] msi: Make the msi code irq based and not vector based.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 14/25] x86_64 irq: Move msi message composition into io_apic.c
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 15/25] i386 irq: Move msi message composition into io_apic.c
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 16/25] msi: Only build msi-apic.c on ia64
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 17/25] x86_64 irq: Remove the msi assumption that irq == vector
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 19/25] irq: Remove msi hacks
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 20/25] irq: Generalize the check for HARDIRQ_BITS.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 21/25] x86_64 irq: Make the external irq handlers report their vector, not the irq number.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 22/25] x86_64 irq: make vector_irq per cpu.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 23/25] x86_64 irq: Kill gsi_irq_sharing.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 24/25] x86_64 irq: Kill irq compression.
- From: "Eric W. Biederman" <[email protected]>
- [PATCH 0/25] Decouple IRQ issues (MSI, i386, x86_64, ia64)
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