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>

2 files changed, 32 insertions, 0 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 96e0c2ebc38..09521332636 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 1485a26ddce..bb1a01f089e 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;
 }