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Date:      Tue, 27 Jan 2009 16:34:54 -0600
From:      Dan Nelson <dnelson@allantgroup.com>
To:        patrick <gibblertron@gmail.com>
Cc:        FreeBSD Questions Mailing List <freebsd-questions@freebsd.org>
Subject:   Re: Control IRQ assignment?
Message-ID:  <20090127223453.GC63837@dan.emsphone.com>
In-Reply-To: <b043a4850901271232q5abe8d86oc04e6bcd5c3eb6a0@mail.gmail.com>
References:  <b043a4850901271232q5abe8d86oc04e6bcd5c3eb6a0@mail.gmail.com>

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In the last episode (Jan 27), patrick said:
> I'm running FreeBSD 7.1 on a new Dell Inspiron 530s. I'm having an issue
> where the same IRQ is being assigned for multiple devices, and I have a
> device that absolutely needs its own IRQ.  The BIOS is very limiting, and
> won't allow me to disable shared IRQ assignment.  Some suggestions I've
> read about booting FreeBSD with ACPI hasn't been an option, because
> without it enabled, FreeBSD does not see the SATA controllers/disks, and
> thus won't boot.  Linux has a utility called irqbalance
> (http://www.irqbalance.org/) that seems like it could be promising, but of
> course it is Linux-specific.  Is there any way in FreeBSD that I can help
> the system decide which IRQs to assign to what?

irqbalance doesn't do what you think it does; it simply pins interrupt
handlers on particular CPUs.  The only way to ensure that a given device has
an IRQ line to itself is to look at your motherboard documentation,
determine which IRQs are wired to which PCI slots, and rearrange your cards
to assign your troublesome device an IRQ of its own.  Some motherboards let
you assign onboard devices (NICs, parallel port, etc) to different
interrupts, too.

-- 
	Dan Nelson
	dnelson@allantgroup.com



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