x86, pci: introduce pci=ioapicreroute kernel cmdline option

Introduce pci=ioapicreroute kernel cmdline option to enable rerouting of boot
interrupts to the primary io-apic.

Signed-off-by: Stefan Assmann <sassmann@suse.de>
Signed-off-by: Olaf Dabrunz <od@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1aebe9d..df262b3 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1521,6 +1521,10 @@
 		noioapicquirk	[APIC] Disable all boot interrupt quirks.
 				Safety option to keep boot IRQs enabled. This
 				should never be necessary.
+		ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
+				primary IO-APIC for bridges that cannot disable
+				boot IRQs. This fixes a source of spurious IRQs
+				when the system masks IRQs.
 		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
 				routing table. These calls are known to be buggy
 				on several machines and they hang the machine