Re: [Qemu-devel] IRQ number, interrupt number, interrupt line & GPIO[in/out]

[Zhi Yong Wu]

On Sat, Mar 3, 2012 at 12:41 AM, Peter Maydell <address@hidden> wrote:
> On 2 March 2012 16:01, Anthony Liguori <address@hidden> wrote:
>> On 03/02/2012 06:38 AM, Zhi Yong Wu wrote:
>>> 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.
>
> The other point to note here is that there are two different sets
> of terminology:
> (1) real world terminology, which is roughly what Anthony is describing
> (2) QEMU qdev and sysbus terms, which don't necessarily always map
> quite cleanly to (1)
Yeah, i also found that they don't cleanly map to real world
teminology. so many interrupt concepts make me get confused.

By the way, i have one question about MSI[-X].
How does Root Complex know if one write transaction is used for
MSI[-X]. When it recieves this transaction request, how it convert it
to one interrupt which CPU can identify?

>
> In particular the QEMU type 'qemu_irq' is really just an arbitrary signal
> (and would be better named GPIO) -- it is not always used for an
> actual interrupt line.
Can you elaborate this?
>
> -- PMM



-- 
Regards,

Zhi Yong Wu