Re: How does OS assign IRQ?
From: KM (konstmor_at_nospam_yahoo.com)
Date: 01/30/05
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Date: Sun, 30 Jan 2005 03:07:53 -0800
Hawk,
> If I can reserve one IRQ from pci card, maybe my problem will disappear.
> During my work, I find some registy keys whose name tell me they may be
> related to reserve some IRQ or Assignment order.
>
> [ HKLM\System\CurrentControlSet\Control\Arbiters\AllocationOrder ]
> [ HKLM\System\CurrentControlSet\Control\Arbiters\ReservedResources ]
>
> [ HKLM\System\CurrentControlSet\Control\SystemResources\AssignmentOrdering ]
> [ HKLM\System\CurrentControlSet\Control\SystemResources\ReservedResources ]
>
> Unfortunately, no change occur even if I change them in my XPe
> configuration.
> and all registry keys return original value.
These registry entries are set by "PnP (Kernel-mode)" component. So if you want to change the entries through your component, make
sure that the component's build order is set above the "PnP (Kernel-mode)" build order.
Or just change the registry values directly at the "PnP (Kernel-mode)" component registry section in TD.
I don't have a clue if it will help you to change the Irq assigment order (it may be easier to test the reg.changes on XP Pro).
--
Regards,
KM
> Furthermore, I find the following registy:
> [ HKLM\System\CurrentControlSet\Control\PnP\PciIrqRouting ]
> I wonder how they work in Windows OS,and
> why my change on above registry value is recovered.
> Best Regards
> Hawk
>
>
> "Slobodan Brcin (eMVP)" <sbrcin@ptt.yu> wrote in message
> news:uOodHQhBFHA.2076@TK2MSFTNGP15.phx.gbl...
> > Hi Hawk,
> >
> > This is tough question.
> >
> > For instance all PCI slots and usually AGP share only 4 wires for IRQ on
> > most motherboards.
> > ISA as legacy might go trough ISA2PCI bridge and share those 4 wires as
> > well.
> >
> > As you can see if you have more than 4 devices some physical int level
> > sharing must be done.
> >
> > Per PCI standard each PCI card can have up to 4 level triggered
> > interrupts. Interrupts are named as INTA# INTB# INTC# INTD#.
> > Most simpler PCI cards are hardwired to use INTA# line and that mean that
> > you can not reassign its interrupt trough software.
> >
> > On motherboards there are usually four lines that connect these lines in
> > some cyclic order. Lines are named IRQW IRQX IRQY IRQZ
> >
> > Following will illustrate how each PCI card in some slot is mapped to MB:
> > IRQW IRQX IRQY IRQZ
> > 0 INTA# INTB# INTC# INTD#.
> > 1 INTB# INTC# INTD# INTA#.
> > 2 INTC# INTD# INTA# INTB#.
> > 3 INTD# INTA# INTB# INTC#.
> > 4 INTA# INTB# INTC# INTD#.
> > ...
> >
> > These lines are connected to APIC that can translate these signals to some
> > IRQ numbers that windows tell it to. But only as long as
> > you do not have hardware IRQ conflict since then IRQ are shared physically
> > not trough software.
> > Some "smarter" PCI cards that use all four IRQ lines allow you to chose
> > one that will be used INTA#..INTD#. So you can avoid
> > collision trough software instead of repluging cards.
> >
> > Also all level triggered interrupts are intended to work together on same
> > IRQ line trough sharing. Each driver then examine hardware
> > that it cover and try to figure out if it should handle that IRQ.
> >
> > There is much more to this, and you should look for it on the net.
> >
> > Depending on your hardware capabilities you should examine:
> > http://search.microsoft.com/search/results.aspx?st=b&na=88&View=en-us&qu=IRQConfig
> >
> > Or rearrange PCI card positions.
> >
> > Regards,
> > Slobodan
> >
> >
> >
> > "Hawk Gauss" <gao.chao@advantech.com.cn> wrote in message
> > news:uToDjHeBFHA.1004@TK2MSFTNGP15.phx.gbl...
> >> Dear All,
> >>
> >> I encounter a problem about IRQ conflict problem.
> >>
> >> BIOS print IRQ15 is assigned to serial bus controller.
> >> But OS re-assign IRQ9 to it, and conflict occur when I insert my PC card
> >> which use ISA IRQ9.
> >> I found USB controller try to change its IRQ9 to IRQ11, which is used by
> >> a
> >> bad device driver. Then the system screen turn blue.:-(
> >>
> >> I can adjust IRQ resource in my BIOS, but there are too many hardware to
> >> modify.
> >> So I decide to find resolution in XPe configuration quickly.
> >>
> >> How does OS manage IRQs for its driver?
> >> Is there any orders for OS to assign IRQ to its PCI devices?
> >>
> >> I am so confused about such problem because it is urgent in my schedule.
> >>
> >> Any help will be appreciated.
> >> Thanks
> >>
> >>
> >
> >
>
>
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