Help with missing IRQs

Discussion in 'Asus' started by Kleptic, Dec 31, 2012.

  1. Kleptic

    Kleptic Guest


    Having a problem finding where my IRQs are hiding. On my board -P5QL
    I have turned off the com ports, the lpt port,the onboard sound and
    video. But when I boot into windows and go to device manager and list
    the IRQ assignments the ones listed are 0,8,9.13.15 thru 21 & 23 along
    with a pile of virtual IRQs (81 to 190). Why aren't the freed IRQ's (2
    thru 7) being utilized? Is the board turning them off when I turn off
    the things usually associated with those IRQs or is it something in
    windows itself keeping those IRQs unused?
    Plugged into the board I have a PCIe graphics card and an ISA
    soundblaster card. On the board I still have the Network adapter
    working and they are all tethered to 16 & 17 which is causing problems
    with the adapter ( I need to constantly reset it). Any pointers

    Kleptic, Dec 31, 2012
    1. Advertisements

  2. Kleptic

    Paul Guest

    If you want some fun, try the ACPI APIC setting.
    That switches from 0..infinity to 0..15 for IRQs.
    Should make for interesting results. It might even
    result in all interrupt servicing, terminating on Core0.

    With regard to things "all tethered on 16 and 17", the things
    connected to 16 could be on the same physical wire. Which makes
    preventing them from sharing, impossible if they're both soldered
    to the motherboard.

    16 ----+-----+ 17 ----+-----+
    | | | |
    Dev1 Dev2 Dev3 Dev4

    Say I have NIC on 16 and Firewire on 16. Then chances are, both chips
    are soldered to the same copper track. The system then, cannot on a
    whim, assign Firewire to 19. Because they're actually, physically
    joined together, and their identities are forever chained together
    as well. If I made Firewire 19, then NIC becomes 19 instantly. They
    cannot be separated.

    With IOAPIC enabled, 16 through 24 or so, are used for peripheral
    bus chips. In the past, that would include devices inside the
    Southbridge (USB), as well as external NIC chips or PCI slot sound
    card. They're in that range. Things joined to the same wires
    (like two PCI cards sharing INTA), are going to be assigned
    the same number. If they're not on the same physical wire,
    then the system can balance the numbers if it wishes.

    The PCI Express cards can use message based interrupts, so while
    your manual has a table showing them "sharing", that probably
    isn't correct. It could be, that the thing that consolidates the
    PCI Express, is wired to a conventional interrupt at some point.
    At that point, there might be some sharing. But not in the nature
    shown by the manual.

    The same comments might apply about the table in the manual,
    regarding the PCI slots. A typical card (one chip on a PCB),
    probably uses INTA, and it's up to the motherboard wiring to
    "swizzle" them. And then, the motherboard manual should show
    a PCI card "assigned" to a particular signal - on the assumption
    that the card uses INTA, and the motherboard rewires that INTA
    signal for balancing (that's the swizzling part). Swizzling
    is the "official" term :)

    I see nothing in the manual to suggest you have the ability to
    edit assignments in 0..15. On older motherboards for example,
    you could move a sound card by such editing (at least, if it
    wasn't sharing with something). Back in the old days, you'd
    use the Asus table in the manual, to find an unshared PCI slot,
    put the sound card in it, then edit the assignments in the BIOS.

    My guess is, your hands are well and truly tied. A PCI or PCI
    Express NIC might help you, a separate purchase. Using the sharing
    table in the manual, you can experiment with making changes that
    way. I would really hope though, that such isn't needed. It all
    should have "just worked", in the year 2012. I could understand
    it being broken, 12 years ago, but not now.

    Paul, Dec 31, 2012
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.