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Re: [Xen-devel] no-carrier on qlogic 8242 10gig with linux 3.x running xen

  • To: "Kristoffer Harthing Egefelt" <k@xxxxxxx>
  • From: "Jan Beulich" <JBeulich@xxxxxxxx>
  • Date: Wed, 28 Mar 2012 14:06:15 +0100
  • Cc: xen-devel <xen-devel@xxxxxxxxxxxxx>
  • Delivery-date: Wed, 28 Mar 2012 13:05:45 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>

>>> On 28.03.12 at 14:57, Kristoffer Harthing Egefelt <k@xxxxxxx> wrote:
> Good stuff - but can you explain how come, in the BIOS, the NIC and the RAID
> controller share IRQ 15, but in /proc/interrupts they have different irqs:
>   16:       6326  xen-pirq-ioapic-level  megasas
>   38:      83524 xen-pirq-ioapic-level  eth0[0], eth1[0]

The BIOS certainly runs the IO-APICs in legacy mode (required to be
able to boot legacy OSes), using just IRQs 0...15 (on a single IO-APIC).
Once ACPI gets enabled, all IO-APIC pins can be used, and hence
sharing of interrupts is generally not needed if there are sufficiently
many pins (and things are properly wired up on the mainboard).

> Does this mean that there shouldn't be any interrupt collisions using
> pci=nomsi ?



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