2 files changed, 32 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 96e0c2ebc388..09521332636b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -665,6 +665,30 @@ config X86_VISWS_APIC
         def_bool y
         depends on X86_32 && X86_VISWS
 
+config X86_REROUTE_FOR_BROKEN_BOOT_IRQS
+        bool "Reroute for broken boot IRQs"
+        default n
+        depends on X86_IO_APIC
+        help
+          This option enables a workaround that fixes a source of
+          spurious interrupts. This is recommended when threaded
+          interrupt handling is used on systems where the generation of
+          superfluous "boot interrupts" cannot be disabled.
+
+          Some chipsets generate a legacy INTx "boot IRQ" when the IRQ
+          entry in the chipset's IO-APIC is masked (as, e.g. the RT
+          kernel does during interrupt handling). On chipsets where this
+          boot IRQ generation cannot be disabled, this workaround keeps
+          the original IRQ line masked so that only the equivalent "boot
+          IRQ" is delivered to the CPUs. The workaround also tells the
+          kernel to set up the IRQ handler on the boot IRQ line. In this
+          way only one interrupt is delivered to the kernel. Otherwise
+          the spurious second interrupt may cause the kernel to bring
+          down (vital) interrupt lines.
+
+          Only affects "broken" chipsets. Interrupt sharing may be
+          increased on these systems.
+
 config X86_MCE
         bool "Machine Check Exception"
         depends on !X86_VOYAGER
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 1485a26ddcef..bb1a01f089e2 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -24,7 +24,11 @@ unsigned int pci_early_dump_regs;
 static int pci_bf_sort;
 int pci_routeirq;
 int noioapicquirk;
+#ifdef CONFIG_X86_REROUTE_FOR_BROKEN_BOOT_IRQS
+int noioapicreroute = 0;
+#else
 int noioapicreroute = 1;
+#endif
 int pcibios_last_bus = -1;
 unsigned long pirq_table_addr;
 struct pci_bus *pci_root_bus;
@@ -528,6 +532,10 @@ char * __devinit  pcibios_setup(char *str)
                 if (noioapicreroute != -1)
                         noioapicreroute = 0;
                 return NULL;
+        } else if (!strcmp(str, "noioapicreroute")) {
+                if (noioapicreroute != -1)
+                        noioapicreroute = 1;
+                return NULL;
         }
         return str;
 }