Re: IRQ 255?

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On Tue, 27 Jan 1998, Bernhard Rosenkraenzer wrote:

>> Bus 0, device 2, function 0:
>> VGA compatible controller: Cirrus Logic GD 7548 (rev 0).
>> Fast devsel. IRQ 255.
>>
>> Note that the video device is on IRQ 255. Is this possibly a bug somewhere?
>
>IRQ 255 doesn't exist, but it looks like a (unsigned char) -1.
>My guess is that your VGA card doesn't use an IRQ, and IRQ 255 is the PCI
>driver's way to display this.

PCI controller sets -1 ( 255 ) IRQ in two cases :
a) The PCI device doesn't need an IRQ.
b) There is no available IRQ to assign to this device.

Bye.

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