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From: John Baldwin <jhb@freebsd.org>
To: freebsd-stable@freebsd.org
Subject: Re: Shared IRQ on ATOM based Soekris net6501 board
Date: Tue, 14 Jan 2014 11:09:18 -0500
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Cc: Christophe Prevotaux <c.prevotaux@rural-networks.com>,
 freebsd-current@freebsd.org
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On Tuesday, January 14, 2014 10:03:46 am Christophe Prevotaux wrote:
> 
> I have found out that when I use 2 AR9580 mini PCIe board
> some irq (namely in that case irq18 is shared over 3 devices)
> 
> I wonder why it is done like this and if this could be something to fix ? 

You can't fix it.  This is how the interrupts are connected on your 
motherboard.  It's true that in PCI-e there are no longer physical
interrupt lines, but the connections may still be hardcoded in silicon.  The 
only chance you might possibly have is to use ACPI (which doesn't work on your 
board) as if the PCI interrupts are hooked up to an interrupt router prior to 
the I/O APIC you might be able to shuffle things.  A far better idea would be 
to use a board that supports MSI interrupts (and/or fix the driver to use MSI 
if it is not doing so already).

-- 
John Baldwin