HI, anthony. On Sat, Mar 3, 2012 at 12:01 AM, Anthony Liguori <anth...@codemonkey.ws> wrote: > Hi Zhi Yong, > > > On 03/02/2012 06:38 AM, Zhi Yong Wu wrote: >> >> HI, >> >> Can anyone explain their relationship and difference among them? It >> is very appreciated if you can make some comments. thanks. > > > IRQ == interrupt. > > GPIO is just another name for an input or output pin on a chip which could > be a IRQ line. > > Interrupt controllers can receive interrupts from one or more devices. > Usually, the input pins on an interrupt controller can be numbered > sequentially. When we say that the first UART is on IRQ number 3, what that > really means is that the IRQ output pin on the UART chip is connected to pin > number 3 on the interrupt controller with a wire. > > But there never is a single interrupt controller in a real system. For > instance, a PCI bus has it's own interrupt controller that has four input > pins (called LNKs) that are oddly labeled A, B, C, D. thanks, i got what they mean. > > For the I440FX PCI bus, those four input pins are mapped to two IRQs which > are then connected to the I/O APIC. What do two IRQs mean here? how will those four input pins be mapped to two IRQs? For example, 8259 interrupt controller is connected to I/O APIC. How will these two IRQs be connected to I/O APIC? i think that those four input pins are connected to I/O APIC with wire, right? Can you elaborate them if you are available? > > Regards, > > Anthony Liguori
-- Regards, Zhi Yong Wu
