PCI IRQ routing table

PCI IRQ routing table

[art stallone]

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Hi all,

 Do ACPI caches PCI IRQ routing table (PIR).
 Is there any ioctl so user space can get that table?

regards,
ART.

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Re: PCI IRQ routing table

[Bjorn Helgaas]

On Thu, 2005-03-31 at 09:58 +0000, art stallone wrote:
> Do ACPI caches PCI IRQ routing table (PIR).
> Is there any ioctl so user space can get that table?

I don't know much about the PIR.  ACPI uses a PCI Routing
Table (_PRT).  ACPI supplies a _PRT for every PCI root bridge.
The ACPI PCI root bridge driver (drivers/acpi/pci_root.c)
parses the _PRT when it claims a new bridge (see the
acpi_pci_root_add() -> acpi_pci_irq_add_prt() path).

There is no convenient user-space mechanism to get the
_PRT.  The _PRT is stored in the DSDT, which you *can*
get, via /proc/acpi/dsdt.  But then you have to disassemble
the DSDT and parse the _PRT yourself.  I.e., you would do
something like "cp /proc/acpi/dsdt dsdt; iasl -d dsdt;
cat dsdt.dsl".

You can get iasl here:
    http://www.intel.com/technology/IAPC/acpi/downloads.htm



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