netdev
[Top] [All Lists]

[PATCH 1/2] Sysfs net class - infrastructure

To: "David S. Miller" <davem@xxxxxxxxxx>, Patrick Mochel <mochel@xxxxxxxx>
Subject: [PATCH 1/2] Sysfs net class - infrastructure
From: Stephen Hemminger <shemminger@xxxxxxxx>
Date: Thu, 15 May 2003 16:27:17 -0700
Cc: netdev@xxxxxxxxxxx, greg@xxxxxxxxx, mochel@xxxxxxxx, jkenisto@xxxxxxxxxx, lkessler@xxxxxxxxxx, Daniel Stekloff <dsteklof@xxxxxxxxxx>
Organization: Open Source Development Lab
Sender: netdev-bounce@xxxxxxxxxxx
This is the network core infrastructure changes for network device
sysfs support.  Previous /sysfs/net support is removed, it was
just an empty place holder. Places where both ioctl and sysfs need
to access the same value were put into one function.

diff -urNp -X dontdiff linux-2.5/include/linux/netdevice.h 
linux-2.5-sysfs/include/linux/netdevice.h
--- linux-2.5/include/linux/netdevice.h 2003-05-13 09:03:54.000000000 -0700
+++ linux-2.5-sysfs/include/linux/netdevice.h   2003-05-15 14:40:13.000000000 
-0700
@@ -28,7 +28,7 @@
 #include <linux/if.h>
 #include <linux/if_ether.h>
 #include <linux/if_packet.h>
-#include <linux/kobject.h>
+#include <linux/device.h>
 
 #include <asm/atomic.h>
 #include <asm/cache.h>
@@ -229,6 +229,7 @@ struct netdev_boot_setup {
 #define NETDEV_BOOT_SETUP_MAX 8
 
 
+
 /*
  *     The DEVICE structure.
  *     Actually, this whole structure is a big mistake.  It mixes I/O
@@ -444,8 +445,16 @@ struct net_device
        struct divert_blk       *divert;
 #endif /* CONFIG_NET_DIVERT */
 
-       /* generic object representation */
-       struct kobject kobj;
+#ifdef CONFIG_NET_SYSFS
+       /* generic device structure */
+       struct device           *dev;
+
+       /* class_device representation */
+       struct class_device     class_dev;
+
+       /* statistics object */
+       struct kobject          stats_kobj;
+#endif
 };
 
 
@@ -563,12 +572,12 @@ static inline void netif_stop_queue(stru
        set_bit(__LINK_STATE_XOFF, &dev->state);
 }
 
-static inline int netif_queue_stopped(struct net_device *dev)
+static inline int netif_queue_stopped(const struct net_device *dev)
 {
        return test_bit(__LINK_STATE_XOFF, &dev->state);
 }
 
-static inline int netif_running(struct net_device *dev)
+static inline int netif_running(const struct net_device *dev)
 {
        return test_bit(__LINK_STATE_START, &dev->state);
 }
@@ -608,7 +617,9 @@ extern int          netif_rx(struct sk_buff *skb
 #define HAVE_NETIF_RECEIVE_SKB 1
 extern int             netif_receive_skb(struct sk_buff *skb);
 extern int             dev_ioctl(unsigned int cmd, void *);
+extern unsigned                dev_get_flags(const struct net_device *);
 extern int             dev_change_flags(struct net_device *, unsigned);
+extern int             dev_set_mtu(struct net_device *, int);
 extern void            dev_queue_xmit_nit(struct sk_buff *skb, struct 
net_device *dev);
 
 extern void            dev_init(void);
@@ -644,7 +655,7 @@ static inline void dev_put(struct net_de
 
 extern void linkwatch_fire_event(struct net_device *dev);
 
-static inline int netif_carrier_ok(struct net_device *dev)
+static inline int netif_carrier_ok(const struct net_device *dev)
 {
        return !test_bit(__LINK_STATE_NOCARRIER, &dev->state);
 }
@@ -836,6 +847,15 @@ extern int         netdev_fastroute_obstacles;
 extern void            dev_clear_fastroute(struct net_device *dev);
 #endif
 
+/* Set the sysfs physical device reference for the network logical device
+ * if set prior to registration will cause a symlink during initialization.
+ */
+#ifdef CONFIG_NET_SYSFS
+#define SET_NETDEV_DEV(net, pdev)      (net)->dev = (pdev)
+#else
+#define SET_NETDEV_DEV(net, pdev)      do { } while(0)
+#endif
+
 
 #endif /* __KERNEL__ */
 
diff -urNp -X dontdiff linux-2.5/net/core/dev.c linux-2.5-sysfs/net/core/dev.c
--- linux-2.5/net/core/dev.c    2003-05-14 10:41:43.000000000 -0700
+++ linux-2.5-sysfs/net/core/dev.c      2003-05-15 14:49:15.000000000 -0700
@@ -201,7 +201,12 @@ int netdev_fastroute;
 int netdev_fastroute_obstacles;
 #endif
 
-static struct subsystem net_subsys;
+#ifdef CONFIG_NET_SYSFS
+extern struct class net_class;
+extern int netdev_create_sysfs(struct net_device *);
+#else
+#define netdev_create_sysfs(net)       ((void)(net), 0)
+#endif
 
 
 
/*******************************************************************************
@@ -2101,6 +2106,22 @@ void dev_set_allmulti(struct net_device 
                dev_mc_upload(dev);
 }
 
+unsigned dev_get_flags(const struct net_device *dev)
+{
+       unsigned flags;
+
+       flags = (dev->flags & ~(IFF_PROMISC |
+                               IFF_ALLMULTI |
+                               IFF_RUNNING)) | 
+               (dev->gflags & (IFF_PROMISC |
+                               IFF_ALLMULTI));
+
+       if (netif_running(dev) && netif_carrier_ok(dev))
+               flags |= IFF_RUNNING;
+
+       return flags;
+}
+
 int dev_change_flags(struct net_device *dev, unsigned flags)
 {
        int ret;
@@ -2163,6 +2184,32 @@ int dev_change_flags(struct net_device *
        return ret;
 }
 
+int dev_set_mtu(struct net_device *dev, int new_mtu)
+{
+       int err;
+
+       if (new_mtu == dev->mtu)
+               return 0;
+
+       /*      MTU must be positive.    */
+       if (new_mtu < 0)
+               return -EINVAL;
+
+       if (!netif_device_present(dev))
+               return -ENODEV;
+
+       err = 0;
+       if (dev->change_mtu)
+               err = dev->change_mtu(dev, new_mtu);
+       else
+               dev->mtu = new_mtu;
+       if (!err && dev->flags & IFF_UP)
+               notifier_call_chain(&netdev_chain,
+                                   NETDEV_CHANGEMTU, dev);
+       return err;
+}
+
+
 /*
  *     Perform the SIOCxIFxxx calls.
  */
@@ -2176,13 +2223,7 @@ static int dev_ifsioc(struct ifreq *ifr,
 
        switch (cmd) {
                case SIOCGIFFLAGS:      /* Get interface flags */
-                       ifr->ifr_flags = (dev->flags & ~(IFF_PROMISC |
-                                                        IFF_ALLMULTI |
-                                                        IFF_RUNNING)) | 
-                                        (dev->gflags & (IFF_PROMISC |
-                                                        IFF_ALLMULTI));
-                       if (netif_running(dev) && netif_carrier_ok(dev))
-                               ifr->ifr_flags |= IFF_RUNNING;
+                       ifr->ifr_flags = dev_get_flags(dev);
                        return 0;
 
                case SIOCSIFFLAGS:      /* Set interface flags */
@@ -2202,27 +2243,7 @@ static int dev_ifsioc(struct ifreq *ifr,
                        return 0;
 
                case SIOCSIFMTU:        /* Set the MTU of a device */
-                       if (ifr->ifr_mtu == dev->mtu)
-                               return 0;
-
-                       /*
-                        *      MTU must be positive.
-                        */
-                       if (ifr->ifr_mtu < 0)
-                               return -EINVAL;
-
-                       if (!netif_device_present(dev))
-                               return -ENODEV;
-
-                       err = 0;
-                       if (dev->change_mtu)
-                               err = dev->change_mtu(dev, ifr->ifr_mtu);
-                       else
-                               dev->mtu = ifr->ifr_mtu;
-                       if (!err && dev->flags & IFF_UP)
-                               notifier_call_chain(&netdev_chain,
-                                                   NETDEV_CHANGEMTU, dev);
-                       return err;
+                       return dev_set_mtu(dev, ifr->ifr_mtu);
 
                case SIOCGIFHWADDR:
                        memcpy(ifr->ifr_hwaddr.sa_data, dev->dev_addr,
@@ -2310,6 +2331,9 @@ static int dev_ifsioc(struct ifreq *ifr,
                                return -EEXIST;
                        memcpy(dev->name, ifr->ifr_newname, IFNAMSIZ);
                        dev->name[IFNAMSIZ - 1] = 0;
+#ifdef CONFIG_NET_SYSFS
+                       snprintf(dev->class_dev.class_id, BUS_ID_SIZE, 
dev->name);
+#endif
                        notifier_call_chain(&netdev_chain,
                                            NETDEV_CHANGENAME, dev);
                        return 0;
@@ -2556,6 +2580,7 @@ int dev_new_index(void)
        }
 }
 
+       
 static int dev_boot_phase = 1;
 
 /**
@@ -2613,11 +2638,10 @@ int register_netdevice(struct net_device
                if (d == dev || !strcmp(d->name, dev->name))
                        goto out_err;
        }
-       snprintf(dev->kobj.name,KOBJ_NAME_LEN,dev->name);
-       kobj_set_kset_s(dev,net_subsys);
-       if ((ret = kobject_register(&dev->kobj)))
-               goto out_err;
        
+       if ((ret = netdev_create_sysfs(dev)))
+           goto out_err;
+
        /* Fix illegal SG+CSUM combinations. */
        if ((dev->features & NETIF_F_SG) &&
            !(dev->features & (NETIF_F_IP_CSUM |
@@ -2843,7 +2867,9 @@ int unregister_netdevice(struct net_devi
                }
        }
 out:
-       kobject_unregister(&dev->kobj);
+#ifdef CONFIG_NET_SYSFS
+       class_device_unregister(&dev->class_dev);
+#endif
        dev_put(dev);
        return 0;
 }
@@ -2862,8 +2888,6 @@ extern void ip_auto_config(void);
 extern void dv_init(void);
 #endif /* CONFIG_NET_DIVERT */
 
-static decl_subsys(net,NULL,NULL);
-
 
 /*
  *       This is called single threaded during boot, so no need
@@ -2879,7 +2903,10 @@ static int __init net_dev_init(void)
        if (dev_proc_init())
                goto out;
 
-       subsystem_register(&net_subsys);
+#ifdef CONFIG_NET_SYSFS
+       if (class_register(&net_class))
+               goto out;
+#endif
 
        INIT_LIST_HEAD(&ptype_all);
        for (i = 0; i < 16; i++) 
@@ -2953,7 +2980,7 @@ static int __init net_dev_init(void)
                 */
                netdev_boot_setup_check(dev);
 
-               if (dev->init && dev->init(dev)) {
+               if ((dev->init && dev->init(dev)) || netdev_create_sysfs(dev)) {
                        /*
                         * It failed to come up. It will be unhooked later.
                         * dev_alloc_name can now advance to next suitable
@@ -3042,3 +3069,4 @@ static int net_run_sbin_hotplug(struct n
        return call_usermodehelper(argv [0], argv, envp, 0);
 }
 #endif
+
diff -urNp -X dontdiff linux-2.5/net/core/Makefile 
linux-2.5-sysfs/net/core/Makefile
--- linux-2.5/net/core/Makefile 2003-04-29 11:54:39.000000000 -0700
+++ linux-2.5-sysfs/net/core/Makefile   2003-05-15 15:04:20.000000000 -0700
@@ -12,6 +12,7 @@ endif
 
 obj-$(CONFIG_NET) += dev.o dev_mcast.o dst.o neighbour.o rtnetlink.o utils.o 
link_watch.o filter.o
 
+obj-$(CONFIG_NET_SYSFS) += net-sysfs.o 
 obj-$(CONFIG_NETFILTER) += netfilter.o
 obj-$(CONFIG_NET_DIVERT) += dv.o
 obj-$(CONFIG_NET_PROFILE) += profile.o
diff -urNp -X dontdiff linux-2.5/net/core/net-sysfs.c 
linux-2.5-sysfs/net/core/net-sysfs.c
--- linux-2.5/net/core/net-sysfs.c      1969-12-31 16:00:00.000000000 -0800
+++ linux-2.5-sysfs/net/core/net-sysfs.c        2003-05-15 16:03:12.000000000 
-0700
@@ -0,0 +1,327 @@
+/*
+ * net-sysfs.c - network device class and attributes
+ *
+ * Copyright (c) 2003 Stephen Hemminber <shemminger@xxxxxxxx>
+ * 
+ *
+ * TODO:
+ * state
+ * last_tx
+ * last_rx
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <net/sock.h>
+#include <linux/rtnetlink.h>
+
+#define to_net_dev(class) container_of((class), struct net_device, class_dev)
+
+/* generate a show function for  simple field */
+#define NETDEVICE_SHOW(field, format_string)                           \
+static ssize_t show_##field(struct class_device *dev, char *buf)       \
+{                                                                      \
+       return sprintf(buf, format_string, to_net_dev(dev)->field);     \
+}
+
+/* generate a store function for a field with locking */
+#define NETDEVICE_STORE(field)                                         \
+static ssize_t                                                                 
\
+store_##field(struct class_device *dev, const char *buf, size_t len)   \
+{                                                                      \
+       char *endp;                                                     \
+       long new = simple_strtol(buf, &endp, 16);                       \
+                                                                       \
+       if (endp == buf || new < 0)                                     \
+               return -EINVAL;                                         \
+                                                                       \
+       if (!capable(CAP_NET_ADMIN))                                    \
+               return -EPERM;                                          \
+                                                                       \
+       rtnl_lock();                                                    \
+       to_net_dev(dev)->field = new;                                   \
+       rtnl_unlock();                                                  \
+       return len;                                                     \
+}
+
+/* generate a read-only network device class attribute */
+#define NETDEVICE_ATTR(field, format_string)                           \
+NETDEVICE_SHOW(field, format_string)                                   \
+static CLASS_DEVICE_ATTR(field, S_IRUGO, show_##field, NULL)           \
+
+NETDEVICE_ATTR(type, "%d\n");
+NETDEVICE_ATTR(addr_len, "%d\n");
+NETDEVICE_ATTR(features, "%#x\n");
+
+/* TODO: only a few devices set this now should fix others. */
+static ssize_t show_port(struct class_device *dev, char *buf)
+{
+       unsigned char port = to_net_dev(dev)->if_port;
+       if (port > IF_PORT_100BASEFX)
+               return sprintf(buf, "%d\n", port);
+       else
+               return sprintf(buf, "%s\n", if_port_text[port]);
+}
+
+static CLASS_DEVICE_ATTR(if_port, S_IRUGO, show_port, NULL);
+
+static ssize_t format_addr(char *buf, const unsigned char *addr, int len)
+{
+       int i;
+       char *cp = buf;
+
+       read_lock(&dev_base_lock);
+       for (i = 0; i < len; i++)
+               cp += sprintf(cp, "%02x%c", addr[i],
+                             i == (len - 1) ? '\n' : ':');
+       read_unlock(&dev_base_lock);
+       return cp - buf;
+}
+
+static ssize_t show_address(struct class_device *dev, char *buf)
+{
+       struct net_device *net = to_net_dev(dev);
+       return format_addr(buf, net->dev_addr, net->addr_len);
+}
+
+static ssize_t show_broadcast(struct class_device *dev, char *buf)
+{
+       struct net_device *net = to_net_dev(dev);
+       return format_addr(buf, net->broadcast, net->addr_len);
+}
+
+static CLASS_DEVICE_ATTR(address, S_IRUGO, show_address, NULL);
+static CLASS_DEVICE_ATTR(broadcast, S_IRUGO, show_broadcast, NULL);
+
+
+/* read-write attributes */
+NETDEVICE_SHOW(mtu, "%d\n");
+
+static ssize_t store_mtu(struct class_device *dev, const char *buf, size_t len)
+{
+       char *endp;
+       int new_mtu;
+       int err;
+
+       new_mtu = simple_strtoul(buf, &endp, 10);
+       if (endp == buf) 
+               return -EINVAL;
+
+       if (!capable(CAP_NET_ADMIN))
+               return -EPERM;
+       
+       rtnl_lock();
+       err = dev_set_mtu(to_net_dev(dev), new_mtu);
+       rtnl_unlock();
+
+       return err == 0 ? len : err;
+}
+
+static CLASS_DEVICE_ATTR(mtu, S_IRUGO | S_IWUSR, show_mtu, store_mtu);
+
+static ssize_t show_flags(struct class_device *dev, char *buf)
+{
+       return sprintf(buf, "%#x\n", dev_get_flags(to_net_dev(dev)));
+}
+
+static ssize_t store_flags(struct class_device *dev, const char *buf, size_t 
len)
+{
+       unsigned long new_flags;
+       char *endp;
+       int err = 0;
+
+       new_flags = simple_strtoul(buf, &endp, 16);
+       if (endp == buf)
+               return -EINVAL;
+
+       if (!capable(CAP_NET_ADMIN))
+               return -EPERM;
+       
+       rtnl_lock();
+       err = dev_change_flags(to_net_dev(dev), new_flags);
+       rtnl_unlock();
+
+       return err ? err : len;
+}
+
+static CLASS_DEVICE_ATTR(flags, S_IRUGO | S_IWUSR, show_flags, store_flags);
+
+
+NETDEVICE_SHOW(tx_queue_len, "%lu\n");
+NETDEVICE_STORE(tx_queue_len);
+
+static CLASS_DEVICE_ATTR(tx_queue_len, S_IRUGO | S_IWUSR, show_tx_queue_len, 
+                        store_tx_queue_len);
+
+NETDEVICE_SHOW(ifindex, "%d\n");
+NETDEVICE_STORE(ifindex);
+
+static CLASS_DEVICE_ATTR(ifindex, S_IRUGO | S_IWUSR, show_ifindex, 
+                        store_ifindex);
+
+struct class net_class = {
+       .name = "net",
+};
+
+
+static struct class_device_attribute *net_class_attributes[] = {
+       &class_device_attr_ifindex,
+       &class_device_attr_addr_len,
+       &class_device_attr_tx_queue_len,
+       &class_device_attr_features,
+       &class_device_attr_mtu,
+       &class_device_attr_flags,
+       &class_device_attr_if_port,
+       &class_device_attr_type,
+       &class_device_attr_address,
+       &class_device_attr_broadcast,
+       NULL
+};
+
+struct netstat_fs_entry {
+       struct attribute attr;
+       ssize_t (*show)(const struct net_device_stats *, char *);
+       ssize_t (*store)(struct net_device_stats *, const char *, size_t);
+};
+
+static ssize_t net_device_stat_show(unsigned long var, char *buf)
+{
+       return sprintf(buf, "%ld\n", var);
+}
+
+/* generate a read-only statistics attribute */
+#define NETDEVICE_STAT(_NAME)                                          \
+static ssize_t show_stat_##_NAME(const struct net_device_stats *stats, \
+                                char *buf)                             \
+{                                                                      \
+       return net_device_stat_show(stats->_NAME, buf);                 \
+}                                                                      \
+static struct netstat_fs_entry net_stat_##_NAME  = {                   \
+       .attr = {.name = __stringify(_NAME), .mode = S_IRUGO },         \
+       .show = show_stat_##_NAME,                                      \
+}
+
+NETDEVICE_STAT(rx_packets);
+NETDEVICE_STAT(tx_packets);
+NETDEVICE_STAT(rx_bytes);
+NETDEVICE_STAT(tx_bytes);
+NETDEVICE_STAT(rx_errors);
+NETDEVICE_STAT(tx_errors);
+NETDEVICE_STAT(rx_dropped);
+NETDEVICE_STAT(tx_dropped);
+NETDEVICE_STAT(multicast);
+NETDEVICE_STAT(collisions);
+NETDEVICE_STAT(rx_length_errors);
+NETDEVICE_STAT(rx_over_errors);
+NETDEVICE_STAT(rx_crc_errors);
+NETDEVICE_STAT(rx_frame_errors);
+NETDEVICE_STAT(rx_fifo_errors);
+NETDEVICE_STAT(rx_missed_errors);
+NETDEVICE_STAT(tx_aborted_errors);
+NETDEVICE_STAT(tx_carrier_errors);
+NETDEVICE_STAT(tx_fifo_errors);
+NETDEVICE_STAT(tx_heartbeat_errors);
+NETDEVICE_STAT(tx_window_errors);
+NETDEVICE_STAT(rx_compressed);
+NETDEVICE_STAT(tx_compressed);
+
+static struct attribute *default_attrs[] = {
+       &net_stat_rx_packets.attr,
+       &net_stat_tx_packets.attr,
+       &net_stat_rx_bytes.attr,
+       &net_stat_tx_bytes.attr,
+       &net_stat_rx_errors.attr,
+       &net_stat_tx_errors.attr,
+       &net_stat_rx_dropped.attr,
+       &net_stat_tx_dropped.attr,
+       &net_stat_multicast.attr,
+       &net_stat_collisions.attr,
+       &net_stat_rx_length_errors.attr,
+       &net_stat_rx_over_errors.attr,
+       &net_stat_rx_crc_errors.attr,
+       &net_stat_rx_frame_errors.attr,
+       &net_stat_rx_fifo_errors.attr,
+       &net_stat_rx_missed_errors.attr,
+       &net_stat_tx_aborted_errors.attr,
+       &net_stat_tx_carrier_errors.attr,
+       &net_stat_tx_fifo_errors.attr,
+       &net_stat_tx_heartbeat_errors.attr,
+       &net_stat_tx_window_errors.attr,
+       &net_stat_rx_compressed.attr,
+       &net_stat_tx_compressed.attr,
+       NULL
+};
+
+
+static ssize_t
+netstat_attr_show(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+       struct netstat_fs_entry *entry
+               = container_of(attr, struct netstat_fs_entry, attr);
+       struct class_device *class_dev
+               = container_of(kobj->parent, struct class_device, kobj);
+       struct net_device *dev
+               = to_net_dev(class_dev);
+       struct net_device_stats *stats 
+               = dev->get_stats ? dev->get_stats(dev) : NULL;
+
+       if (stats && entry->show) 
+               return entry->show(stats, buf);
+       return -EINVAL;
+}
+
+static struct sysfs_ops netstat_sysfs_ops = {
+       .show = netstat_attr_show,
+};
+
+static struct kobj_type netstat_ktype = {
+       .sysfs_ops      = &netstat_sysfs_ops,
+       .default_attrs  = default_attrs,
+};
+
+/* Create sysfs entries for network device. */
+int netdev_create_sysfs(struct net_device *net)
+{
+       struct class_device *class_dev = &(net->class_dev);
+       int i;
+       struct class_device_attribute *attr;
+       int ret;
+
+       memset(class_dev, 0, sizeof(struct class_device)); 
+       class_dev->class = &net_class;
+       class_dev->dev = net->dev;
+       class_dev->class_data = net;
+
+       snprintf(class_dev->class_id, BUS_ID_SIZE, net->name);
+       if ((ret = class_device_register(class_dev)))
+               goto out;
+
+       for (i = 0; (attr = net_class_attributes[i]); i++) {
+               if ((ret = class_device_create_file(class_dev, attr)))
+                   goto out_unreg;
+       }
+
+       if (net->get_stats) {
+               struct kobject *k = &net->stats_kobj;
+
+               memset(k, 0, sizeof(*k));
+               k->parent = kobject_get(&class_dev->kobj);
+               if (!k->parent) {
+                       ret = -EBUSY;
+                       goto out_unreg;
+               }
+
+               snprintf(k->name, KOBJ_NAME_LEN, "%s", "statistics");
+               k->ktype = &netstat_ktype;
+
+               if((ret = kobject_register(k))) 
+                        goto out_unreg; 
+       }
+
+out:
+       return ret;
+out_unreg:
+       class_device_unregister(class_dev);
+       goto out;
+}
diff -urNp -X dontdiff linux-2.5/net/Kconfig linux-2.5-sysfs/net/Kconfig
--- linux-2.5/net/Kconfig       2003-05-14 10:41:43.000000000 -0700
+++ linux-2.5-sysfs/net/Kconfig 2003-05-15 14:51:59.000000000 -0700
@@ -58,6 +58,18 @@ config NETLINK_DEV
          the real netlink socket.
          This is a backward compatibility option, choose Y for now.
 
+config NET_SYSFS
+       bool "Sysfs support for network devices"
+       default y
+       ---help---
+          Show network devices in the sysfs virtual file system.
+          This allows accessing network device information through
+          files, for example /sys/class/net/eth0/address contains
+          the Ethernet address.
+
+          Some parameters (like MTU) can also be set through this
+          interface.
+
 config NETFILTER
        bool "Network packet filtering (replaces ipchains)"
        ---help---

<Prev in Thread] Current Thread [Next in Thread>