Re: Interrupt storm

John Baldwin <jhb_at_FreeBSD.org> wrote:
> Yes, I am.  However, what this is doing is going and looking to see if the 
> BIOS has programmed a valid IRQ into any of the devices routed by this IRQ, 
> and if so, we (currently) trust what the BIOS says over what the link claims 
> as far as what the best IRQ to use is.  If the BIOS is just confused but the 
> BIOS IRQ is still valid in _PRS then the fact that we always do an _SRS means 
> we are still ok.  The real problem here is that for this machine, calling 
> _DIS seems to permanently break the link devices.  I think we'll have to add 
> a quirk to disable calling _DIS.  I wonder if Linux already has such a quirk 
> for this box or if they are more selective about how and when they call _DIS.

Hi,

I was wondering why ACPI pci link code from RELENG_5 worked (it called
_DIS too) and I noticed this in my dmesg:
- pci_link[0-14] are attached
- then pci0, pcib0 and other devices are attached
- then pci_link[15-31] are attached
- then other devices are attached

I thought that perhaps the problem was that _DIS was called after
devices had already been attached and had allocated an irq.

So I tried this patch:

%%%
Index: acpi_pci_link.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/acpica/acpi_pci_link.c,v
retrieving revision 1.44
diff -u -p -r1.44 acpi_pci_link.c
--- acpi_pci_link.c     18 Jan 2005 20:18:46 -0000      1.44
+++ acpi_pci_link.c     8 Apr 2005 11:19:29 -0000
_at__at_ -511,7 +511,8 _at__at_ acpi_pci_link_attach(device_t dev)
 	 * run _DIS (i.e., the method doesn't exist), assume the initial
 	 * IRQ was routed by the BIOS. */
-	if (ACPI_SUCCESS(AcpiEvaluateObject(acpi_get_handle(dev), "_DIS", NULL,
+	if (device_get_unit(dev) <= 14 &&
+	    ACPI_SUCCESS(AcpiEvaluateObject(acpi_get_handle(dev), "_DIS", NULL,
 	    NULL)))
 		for (i = 0; i < sc->pl_num_links; i++)
 			sc->pl_links[i].l_irq = PCI_INVALID_IRQ;
%%%

With this patch, sk0 uses irq9 but everything works fine (no timeouts,
no interrupt storms).
I don't know if my idea is totally silly or not ...
Perhaps the pci links should be all attached before other devices are
attached ?

Cheers,

Antoine