x86, pci: introduce config option for pci reroute quirks (was: [PATCH 0/3] Boot IRQ quirks for Broadcom and AMD/ATI)

This is against linux-2.6-tip, branch pci-ioapic-boot-irq-quirks.

From: Stefan Assmann <sassmann@suse.de>
Subject: Introduce config option for pci reroute quirks

The config option X86_REROUTE_FOR_BROKEN_BOOT_IRQS is introduced to
enable (or disable) the redirection of the interrupt handler to the boot
interrupt line by default. Depending on the existence of interrupt
masking / threaded interrupt handling in the kernel (vanilla, rt, ...)
and the maturity of the rerouting patch, users can enable or disable the
redirection by default.

This means that the reroute quirk can be applied to any kernel without
changing it.

Interrupt sharing could be increased if this option is enabled. However this
option is vital for threaded interrupt handling, as done by the RT kernel.
It should simplify the consolidation with the RT kernel.

The option can be overridden by either pci=ioapicreroute or
pci=noioapicreroute.
Signed-off-by: Stefan Assmann <sassmann@suse.de>
Signed-off-by: Olaf Dabrunz <od@suse.de>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Jon Masters <jonathan@jonmasters.org>
Cc: Ihno Krumreich <ihno@suse.de>
Cc: Sven Dietrich <sdietrich@suse.de>
Cc: Daniel Gollub <dgollub@suse.de>
Cc: Felix Foerster <ffoerster@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>