Allows msi to be selected as a preferred mode.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

--- a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c	2014-07-18 08:47:24.713604900 -0700
+++ b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c	2014-07-18 08:47:24.709604886 -0700
@@ -646,7 +646,7 @@ fail_release_iomem:
 	igbuio_pci_release_iomem(&udev->info);
 	if (udev->mode == RTE_INTR_MODE_MSIX)
 		pci_disable_msix(udev->pdev);
-	if (udev->mode == RTE_INTR_MODE_MSI)
+	else if (udev->mode == RTE_INTR_MODE_MSI)
 		pci_disable_msi(udev->pdev);
 	pci_release_regions(dev);
 fail_disable:
@@ -661,6 +661,7 @@ static void
 igbuio_pci_remove(struct pci_dev *dev)
 {
 	struct uio_info *info = pci_get_drvdata(dev);
+	struct rte_uio_pci_dev *udev = igbuio_get_uio_pci_dev(info);
 
 	if (info->priv == NULL) {
 		pr_notice("Not igbuio device\n");
@@ -670,9 +671,10 @@ igbuio_pci_remove(struct pci_dev *dev)
 	sysfs_remove_group(&dev->dev.kobj, &dev_attr_grp);
 	uio_unregister_device(info);
 	igbuio_pci_release_iomem(info);
-	if (((struct rte_uio_pci_dev *)info->priv)->mode ==
-			RTE_INTR_MODE_MSIX)
+	if (udev->mode == RTE_INTR_MODE_MSIX)
 		pci_disable_msix(dev);
+	else if (udev->mode == RTE_INTR_MODE_MSI)
+		pci_disable_msi(dev);
 	pci_release_regions(dev);
 	pci_disable_device(dev);
 	pci_set_drvdata(dev, NULL);
@@ -690,6 +692,9 @@ igbuio_config_intr_mode(char *intr_str)
 	if (!strcmp(intr_str, RTE_INTR_MODE_MSIX_NAME)) {
 		igbuio_intr_mode_preferred = RTE_INTR_MODE_MSIX;
 		pr_info("Use MSIX interrupt\n");
+	} else if (!strcmp(intr_str, RTE_INTR_MODE_MSI_NAME)) {
+		igbuio_intr_mode_preferred = RTE_INTR_MODE_MSI;
+		pr_info("Use MSI interrupt\n");
 	} else if (!strcmp(intr_str, RTE_INTR_MODE_LEGACY_NAME)) {
 		igbuio_intr_mode_preferred = RTE_INTR_MODE_LEGACY;
 		pr_info("Use legacy interrupt\n");
@@ -733,6 +738,7 @@ module_param(intr_mode, charp, S_IRUGO);
 MODULE_PARM_DESC(intr_mode,
 "igb_uio interrupt mode (default=msix):\n"
 "    " RTE_INTR_MODE_MSIX_NAME "       Use MSIX interrupt\n"
+"    " RTE_INTR_MODE_MSI_NAME "       Use MSI interrupt\n"
 "    " RTE_INTR_MODE_LEGACY_NAME "     Use Legacy interrupt\n"
 "\n");