From mboxrd@z Thu Jan  1 00:00:00 1970
From: ebiederm@xmission.com (Eric W. Biederman)
Subject: [PATCH 0/25] Decouple IRQ issues (MSI, i386, x86_64, ia64)
Date: Tue, 20 Jun 2006 16:24:35 -0600
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Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz, discuss@x86-64.org, Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>, Andi Kleen <ak@suse.de>, Natalie Protasevich <Natalie.Protasevich@UNISYS.com>, Len Brown <len.brown@intel.com>, Kimball Murray <kimball.murray@gmail.com>, Brice Goglin <brice@myri.com>, Greg Lindahl <greg.lindahl@qlogic.com>, Dave Olson <olson@unixfolk.com>, Jeff Garzik <jeff@garzik.org>, Greg KH <gregkh@suse.de>, Grant Grundler <iod00d@hp.com>, "bibo,mao" <bibo.mao@intel.com>, Rajesh Shah <rajesh.shah@intel.com>, Mark Maule <maule@sgi.com>, Jesper Juhl <jesper.juhl@gmail.com>, Shaohua Li <shaohua.li@intel.com>, Matthew Wilcox <matthew@wil.cx>, "Michael S. Tsirkin" <mst@mellanox.co.il>, Ashok Raj <ashok.raj@intel.com>, Randy Dunlap <rdunlap@xenotime.net>Roland Dreier <rd>


The following patchset is against 2.6.17-rc6-mm2.
It was the only easy place I could get everyones work who has been
touching relevant code.

The primary aim of this patch is to remove maintenances problems caused
by the irq infrastructure.  The two big issues I address are an
artificially small cap on the number of irqs, and that MSI assumes
vector == irq.  My primary focus is on x86_64 but I have touched
other architectures where necessary to keep them from breaking.

- To increase the number of irqs I modify the code to look at
  the (cpu, vector) pair instead of just  looking at the vector.

  With a large number of irqs available systems with a large irq
  count no longer need to compress their irq numbers to fit.
  Removing a lot of brittle special cases.

  For acpi guys the result is that irq == gsi.

- Addressing the fact that MSI assumes irq == vector takes a few more
  patches.  But suffice it to say when I am done none of the generic
  irq code even knows what a vector is.

In quick testing on a large Unisys x86_64 machine we stumbled over at
least one driver that assumed that NR_IRQS could always fit into an 8
bit number.  This driver is clearly buggy today.  But this has become
a class of bugs that it is now much easier to hit. 

I've done my best but if this patchset wasn't perfect it won't
surprise me.  But I'm pretty certain I have succeeded in decoupling
any fixes should be small and well contained.

Eric