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On 27 Jul, 20:55, John Jordan <j...@xxxxxxxxxxxx> wrote:
> A PCI bus has four IRQ lines (usually
> termed A-D) which are hardwired to slots. Each of these is then mapped
> to one of the PIC IRQ lines, which are frequently shared with other
> devices in modern PCs.
>
> The usual process for shared IRQs is that when the driver's IRQ handler
> is called, it first asks its device whether it triggered the IRQ. If
> not, it hands control to the next driver in the chain. As a result, IRQ
> clashes should only be a problem for modern OSs if a driver is very
> badly written.
The problem is, I'm using a USB keyboard. If I set it (in the BIOS
setup screen) to be handled by the OS, it is unresponsive during the
boot screens of Windows and Linux, because no USB keyboard drivers
have been loaded at that point by the OS.
If I set it to be handled by the BIOS, the BIOS keyboard handling
routines don't seem to support IRQ sharing with the PCI slot on the
same IRQ line. I think it basically emulates a PS/2 keyboard, albeit
with a different IRQ#.
I'm using an Abit NF7-S v2, if that makes any difference.
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