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--- linux-2.6.30.noarch/Documentation/kernel-parameters.txt~	2009-06-24 14:25:04.000000000 -0400
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+++ linux-2.6.30.noarch/Documentation/kernel-parameters.txt	2009-06-24 14:25:32.000000000 -0400
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@@ -1811,6 +1811,9 @@ and is between 256 and 4096 characters. 
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 		check_enable_amd_mmconf [X86] check for and enable
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 				properly configured MMIO access to PCI
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 				config space on AMD family 10h CPU
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+		msi		[MSI] If the PCI_MSI kernel config parameter is
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+				enabled, this kernel boot option can be used to
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+				enable the use of MSI interrupts system-wide.
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 		nomsi		[MSI] If the PCI_MSI kernel config parameter is
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 				enabled, this kernel boot option can be used to
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 				disable the use of MSI interrupts system-wide.
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diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
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index 2a4501d..209758c 100644
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--- a/drivers/pci/Kconfig
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+++ b/drivers/pci/Kconfig
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@@ -21,6 +21,18 @@ config PCI_MSI
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 	   If you don't know what to do here, say N.
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+config PCI_MSI_DEFAULT_ON
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+	def_bool y
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+	prompt "Use Message Signaled Interrupts by default"
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+	depends on PCI_MSI
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+	help
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+	  Selecting this option will enable use of PCI MSI where applicable
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+	  by default. Support for MSI can be disabled through the use of the
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+	  pci=nomsi boot flag. Conversely, if this option is not selected,
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+	  support for PCI MSI can be enabled by passing the pci=msi flag.
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+
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+	  If you don't know what to do here, say N.
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+
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 config PCI_LEGACY
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 	bool "Enable deprecated pci_find_* API"
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 	depends on PCI
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diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
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index 896a15d..53df583 100644
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--- a/drivers/pci/msi.c
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+++ b/drivers/pci/msi.c
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@@ -23,7 +23,11 @@
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 #include "pci.h"
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 #include "msi.h"
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+#ifdef CONFIG_PCI_MSI_DEFAULT_ON
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 static int pci_msi_enable = 1;
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+#else
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+static int pci_msi_enable = 0;
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+#endif /*CONFIG_PCI_MSI_DEFAULT_ON*/
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 /* Arch hooks */
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@@ -786,6 +790,11 @@ int pci_msi_enabled(void)
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 }
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 EXPORT_SYMBOL(pci_msi_enabled);
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+void pci_yes_msi(void)
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+{
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+	pci_msi_enable = 1;
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+}
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+
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 void pci_msi_init_pci_dev(struct pci_dev *dev)
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 {
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 	INIT_LIST_HEAD(&dev->msi_list);
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diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
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index 17bd932..e9bc9fe 100644
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--- a/drivers/pci/pci.c
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+++ b/drivers/pci/pci.c
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@@ -2393,6 +2393,8 @@ static int __init pci_setup(char *str)
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 		if (*str && (str = pcibios_setup(str)) && *str) {
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 			if (!strcmp(str, "nomsi")) {
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 				pci_no_msi();
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+			} else if (!strcmp(str, "msi")) {
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+				pci_yes_msi();
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 			} else if (!strcmp(str, "noaer")) {
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 				pci_no_aer();
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 			} else if (!strcmp(str, "nodomains")) {
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diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
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index 26ddf78..85efe81 100644
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--- a/drivers/pci/pci.h
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+++ b/drivers/pci/pci.h
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@@ -111,9 +111,11 @@ extern unsigned int pci_pm_d3_delay;
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 #ifdef CONFIG_PCI_MSI
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 void pci_no_msi(void);
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+void pci_yes_msi(void);
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 extern void pci_msi_init_pci_dev(struct pci_dev *dev);
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 #else
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 static inline void pci_no_msi(void) { }
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+static inline void pci_yes_msi(void) { }
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 static inline void pci_msi_init_pci_dev(struct pci_dev *dev) { }
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 #endif
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