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Message-ID: <20070526235515.GA31023@colo.lackof.org>
Date: Sat, 26 May 2007 17:55:15 -0600
From: Grant Grundler <grundler@...isc-linux.org>
To: David Miller <davem@...emloft.net>
Cc: abraham.manu@...il.com, rdreier@...co.com, greg@...ah.com,
linux-pci@...ey.karlin.mff.cuni.cz, linux-kernel@...r.kernel.org
Subject: Re: PCIE
On Sat, May 26, 2007 at 03:49:10PM -0700, David Miller wrote:
> From: Manu Abraham <abraham.manu@...il.com>
> Date: Sat, 26 May 2007 19:03:12 +0400
>
> > i presume then i shouldn't be using IRQF_SHARED, if using MSI.
>
> That's actually a really good question.
>
> It is likely architecture dependant whether the PCI controller wires
> unique MSI interrupts to shared cpu interrupt lines.
MSI (and MSI-X) vectors are required to be exclusive.
I submitted that change to pci.txt last year:
http://lkml.org/lkml/2006/12/25/2
and ISTR I've posted that bit of the PCI spec a few years ago.
But it probably was to linux-pci mailing list only.
> I can imagine many systems where the cpu simply doesn't have enough
> interrupt pins to uniquely identify every possible MSI interrupt
> source.
The cpus haven't been using interrupt pins for a long time now.
Anything with a Local-xAPIC is already using transactions to
signal interrupts even if the OS isn't aware of it.
hth,
grant
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