pci: add option --create-uio-dev to run without hotplug

When the user specifies --create-uio-dev in dpdk eal start options, the
DPDK will create the /dev/uioX instead of waiting that a program does it
(which is usually hotplug).

This option is useful in embedded environments where there is no hotplug
to do the work.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>

lib/librte_eal/linuxapp/eal/eal.c

@@ -94,6 +94,7 @@
 #define OPT_SYSLOG      "syslog"
 #define OPT_BASE_VIRTADDR   "base-virtaddr"
 #define OPT_XEN_DOM0    "xen-dom0"
+#define OPT_CREATE_UIO_DEV "create-uio-dev"
 
 #define RTE_EAL_BLACKLIST_SIZE	0x100
 
@@ -355,6 +356,7 @@ eal_usage(const char *prgname)
 	       "  --"OPT_VMWARE_TSC_MAP": use VMware TSC map instead of "
 	    		   "native RDTSC\n"
 	       "  --"OPT_BASE_VIRTADDR": specify base virtual address\n"
+	       "  --"OPT_CREATE_UIO_DEV": create /dev/uioX (usually done by hotplug)\n"
 	       "\nEAL options for DEBUG use only:\n"
 	       "  --"OPT_NO_HUGE"  : use malloc instead of hugetlbfs\n"
 	       "  --"OPT_NO_PCI"   : disable pci\n"
@@ -638,6 +640,7 @@ eal_parse_args(int argc, char **argv)
 		{OPT_SYSLOG, 1, NULL, 0},
 		{OPT_BASE_VIRTADDR, 1, 0, 0},
 		{OPT_XEN_DOM0, 0, 0, 0},
+		{OPT_CREATE_UIO_DEV, 1, NULL, 0},
 		{0, 0, 0, 0}
 	};
 	struct shared_driver *solib;
@@ -797,6 +800,9 @@ eal_parse_args(int argc, char **argv)
 					return -1;
 				}
 			}
+			else if (!strcmp(lgopts[option_index].name, OPT_CREATE_UIO_DEV)) {
+				internal_config.create_uio_dev = 1;
+			}
 			break;
 
 		default:

lib/librte_eal/linuxapp/eal/eal_pci.c

@@ -460,6 +460,47 @@ pci_uio_map_secondary(struct rte_pci_device *dev)
 	return -1;
 }
 
+static int pci_mknod_uio_dev(const char *sysfs_uio_path, unsigned uio_num)
+{
+	FILE *f;
+	char filename[PATH_MAX];
+	int ret;
+	unsigned major, minor;
+	dev_t dev;
+
+	/* get the name of the sysfs file that contains the major and minor
+	 * of the uio device and read its content */
+	rte_snprintf(filename, sizeof(filename), "%s/dev", sysfs_uio_path);
+
+	f = fopen(filename, "r");
+	if (f == NULL) {
+		RTE_LOG(ERR, EAL, "%s(): cannot open sysfs to get major:minor\n",
+			__func__);
+		return -1;
+	}
+
+	ret = fscanf(f, "%d:%d", &major, &minor);
+	if (ret != 2) {
+		RTE_LOG(ERR, EAL, "%s(): cannot parse sysfs to get major:minor\n",
+			__func__);
+		fclose(f);
+		return -1;
+	}
+	fclose(f);
+
+	/* create the char device "mknod /dev/uioX c major minor" */
+	rte_snprintf(filename, sizeof(filename), "/dev/uio%u", uio_num);
+	dev = makedev(major, minor);
+	ret = mknod(filename, S_IFCHR | S_IRUSR | S_IWUSR, dev);
+	if (f == NULL) {
+		RTE_LOG(ERR, EAL, "%s(): mknod() failed %s\n",
+			__func__, strerror(errno));
+		return -1;
+	}
+
+	return ret;
+}
+
 /*
  * Return the uioX char device used for a pci device. On success, return
  * the UIO number and fill dstbuf string with the path of the device in
@@ -529,7 +570,11 @@ static int pci_get_uio_dev(struct rte_pci_device *dev, char *dstbuf,
 	if (e == NULL)
 		return -1;
 
-	return 0;
+	/* create uio device if we've been asked to */
+	if (internal_config.create_uio_dev && pci_mknod_uio_dev(dstbuf, uio_num) < 0)
+		RTE_LOG(WARNING, EAL, "Cannot create /dev/uio%u\n", uio_num);
+
+	return uio_num;
 }
 
 /* map the PCI resource of a PCI device in virtual memory */

lib/librte_eal/linuxapp/eal/include/eal_internal_cfg.h

@@ -69,6 +69,7 @@ struct internal_config {
 	volatile unsigned vmware_tsc_map; /**< true to use VMware TSC mapping
 										* instead of native TSC */
 	volatile unsigned no_shconf;      /**< true if there is no shared config */
+	volatile unsigned create_uio_dev; /**< true to create /dev/uioX devices */
 	volatile enum rte_proc_type_t process_type; /**< multi-process proc type */
 	/** true to try allocating memory on specific sockets */
 	volatile unsigned force_sockets;