linux_old1/Documentation/ABI/testing/sysfs-class-net

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net: add name_assign_type netdev attribute Based on a patch by David Herrmann. The name_assign_type attribute gives hints where the interface name of a given net-device comes from. These values are currently defined: NET_NAME_ENUM: The ifname is provided by the kernel with an enumerated suffix, typically based on order of discovery. Names may be reused and unpredictable. NET_NAME_PREDICTABLE: The ifname has been assigned by the kernel in a predictable way that is guaranteed to avoid reuse and always be the same for a given device. Examples include statically created devices like the loopback device and names deduced from hardware properties (including being given explicitly by the firmware). Names depending on the order of discovery, or in any other way on the existence of other devices, must not be marked as PREDICTABLE. NET_NAME_USER: The ifname was provided by user-space during net-device setup. NET_NAME_RENAMED: The net-device has been renamed from userspace. Once this type is set, it cannot change again. NET_NAME_UNKNOWN: This is an internal placeholder to indicate that we yet haven't yet categorized the name. It will not be exposed to userspace, rather -EINVAL is returned. The aim of these patches is to improve user-space renaming of interfaces. As a general rule, userspace must rename interfaces to guarantee that names stay the same every time a given piece of hardware appears (at boot, or when attaching it). However, there are several situations where userspace should not perform the renaming, and that depends on both the policy of the local admin, but crucially also on the nature of the current interface name. If an interface was created in repsonse to a userspace request, and userspace already provided a name, we most probably want to leave that name alone. The main instance of this is wifi-P2P devices created over nl80211, which currently have a long-standing bug where they are getting renamed by udev. We label such names NET_NAME_USER. If an interface, unbeknown to us, has already been renamed from userspace, we most probably want to leave also that alone. This will typically happen when third-party plugins (for instance to udev, but the interface is generic so could be from anywhere) renames the interface without informing udev about it. A typical situation is when you switch root from an installer or an initrd to the real system and the new instance of udev does not know what happened before the switch. These types of problems have caused repeated issues in the past. To solve this, once an interface has been renamed, its name is labelled NET_NAME_RENAMED. In many cases, the kernel is actually able to name interfaces in such a way that there is no need for userspace to rename them. This is the case when the enumeration order of devices, or in fact any other (non-parent) device on the system, can not influence the name of the interface. Examples include statically created devices, or any naming schemes based on hardware properties of the interface. In this case the admin may prefer to use the kernel-provided names, and to make that possible we label such names NET_NAME_PREDICTABLE. We want the kernel to have tho possibilty of performing predictable interface naming itself (and exposing to userspace that it has), as the information necessary for a proper naming scheme for a certain class of devices may not be exposed to userspace. The case where renaming is almost certainly desired, is when the kernel has given the interface a name using global device enumeration based on order of discovery (ethX, wlanY, etc). These naming schemes are labelled NET_NAME_ENUM. Lastly, a fallback is left as NET_NAME_UNKNOWN, to indicate that a driver has not yet been ported. This is mostly useful as a transitionary measure, allowing us to label the various naming schemes bit by bit. v8: minor documentation fixes v9: move comment to the right commit Signed-off-by: Tom Gundersen <teg@jklm.no> Reviewed-by: David Herrmann <dh.herrmann@gmail.com> Reviewed-by: Kay Sievers <kay@vrfy.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-07-14 22:37:22 +08:00
What: /sys/class/net/<iface>/name_assign_type
Date: July 2014
KernelVersion: 3.17
Contact: netdev@vger.kernel.org
Description:
Indicates the name assignment type. Possible values are:
1: enumerated by the kernel, possibly in an unpredictable way
2: predictably named by the kernel
3: named by userspace
4: renamed
What: /sys/class/net/<iface>/addr_assign_type
Date: July 2010
KernelVersion: 3.2
Contact: netdev@vger.kernel.org
Description:
Indicates the address assignment type. Possible values are:
0: permanent address
1: randomly generated
2: stolen from another device
3: set using dev_set_mac_address
What: /sys/class/net/<iface>/addr_len
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Indicates the hardware address size in bytes.
Values vary based on the lower-level protocol used by the
interface (Ethernet, FDDI, ATM, IEEE 802.15.4...). See
include/uapi/linux/if_*.h for actual values.
What: /sys/class/net/<iface>/address
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Hardware address currently assigned to this interface.
Format is a string, e.g: 00:11:22:33:44:55 for an Ethernet MAC
address.
What: /sys/class/net/<bridge iface>/bridge/group_fwd_mask
Date: January 2012
KernelVersion: 3.2
Contact: netdev@vger.kernel.org
Description:
Bitmask to allow forwarding of link local frames with address
01-80-C2-00-00-0X on a bridge device. Only values that set bits
not matching BR_GROUPFWD_RESTRICTED in net/bridge/br_private.h
allowed.
Default value 0 does not forward any link local frames.
Restricted bits:
0: 01-80-C2-00-00-00 Bridge Group Address used for STP
1: 01-80-C2-00-00-01 (MAC Control) 802.3 used for MAC PAUSE
2: 01-80-C2-00-00-02 (Link Aggregation) 802.3ad
Any values not setting these bits can be used. Take special
care when forwarding control frames e.g. 802.1X-PAE or LLDP.
What: /sys/class/net/<iface>/broadcast
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Hardware broadcast address for this interface. Format is a
string, e.g: ff:ff:ff:ff:ff:ff for an Ethernet broadcast MAC
address.
What: /sys/class/net/<iface>/carrier
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Indicates the current physical link state of the interface.
Posssible values are:
0: physical link is down
1: physical link is up
Note: some special devices, e.g: bonding and team drivers will
allow this attribute to be written to force a link state for
operating correctly and designating another fallback interface.
What: /sys/class/net/<iface>/dev_id
Date: April 2008
KernelVersion: 2.6.26
Contact: netdev@vger.kernel.org
Description:
Indicates the device unique identifier. Format is an hexadecimal
value. This is used to disambiguate interfaces which might be
stacked (e.g: VLAN interfaces) but still have the same MAC
address as their parent device.
What: /sys/class/net/<iface>/dormant
Date: March 2006
KernelVersion: 2.6.17
Contact: netdev@vger.kernel.org
Description:
Indicates whether the interface is in dormant state. Possible
values are:
0: interface is not dormant
1: interface is dormant
This attribute can be used by supplicant software to signal that
the device is not usable unless some supplicant-based
authentication is performed (e.g: 802.1x). 'link_mode' attribute
will also reflect the dormant state.
What: /sys/clas/net/<iface>/duplex
Date: October 2009
KernelVersion: 2.6.33
Contact: netdev@vger.kernel.org
Description:
Indicates the interface latest or current duplex value. Possible
values are:
half: half duplex
full: full duplex
Note: This attribute is only valid for interfaces that implement
the ethtool get_settings method (mostly Ethernet).
What: /sys/class/net/<iface>/flags
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Indicates the interface flags as a bitmask in hexadecimal. See
include/uapi/linux/if.h for a list of all possible values and
the flags semantics.
What: /sys/class/net/<iface>/ifalias
Date: September 2008
KernelVersion: 2.6.28
Contact: netdev@vger.kernel.org
Description:
Indicates/stores an interface alias name as a string. This can
be used for system management purposes.
What: /sys/class/net/<iface>/ifindex
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Indicates the system-wide interface unique index identifier as a
decimal number. This attribute is used for mapping an interface
identifier to an interface name. It is used throughout the
networking stack for specifying the interface specific
requests/events.
What: /sys/class/net/<iface>/iflink
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Indicates the system-wide interface unique index identifier a
the interface is linked to. Format is decimal. This attribute is
used to resolve interfaces chaining, linking and stacking.
Physical interfaces have the same 'ifindex' and 'iflink' values.
What: /sys/class/net/<iface>/link_mode
Date: March 2006
KernelVersion: 2.6.17
Contact: netdev@vger.kernel.org
Description:
Indicates the interface link mode, as a decimal number. This
attribute should be used in conjunction with 'dormant' attribute
to determine the interface usability. Possible values:
0: default link mode
1: dormant link mode
What: /sys/class/net/<iface>/mtu
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Indicates the interface currently configured MTU value, in
bytes, and in decimal format. Specific values depends on the
lower-level interface protocol used. Ethernet devices will show
a 'mtu' attribute value of 1500 unless changed.
What: /sys/class/net/<iface>/netdev_group
Date: January 2011
KernelVersion: 2.6.39
Contact: netdev@vger.kernel.org
Description:
Indicates the interface network device group, as a decimal
integer. Default value is 0 which corresponds to the initial
network devices group. The group can be changed to affect
routing decisions (see: net/ipv4/fib_rules and
net/ipv6/fib6_rules.c).
What: /sys/class/net/<iface>/operstate
Date: March 2006
KernelVersion: 2.6.17
Contact: netdev@vger.kernel.org
Description:
Indicates the interface RFC2863 operational state as a string.
Possible values are:
"unknown", "notpresent", "down", "lowerlayerdown", "testing",
"dormant", "up".
What: /sys/class/net/<iface>/phys_port_id
Date: July 2013
KernelVersion: 3.12
Contact: netdev@vger.kernel.org
Description:
Indicates the interface unique physical port identifier within
the NIC, as a string.
What: /sys/class/net/<iface>/phys_port_name
Date: March 2015
KernelVersion: 4.0
Contact: netdev@vger.kernel.org
Description:
Indicates the interface physical port name within the NIC,
as a string.
What: /sys/class/net/<iface>/speed
Date: October 2009
KernelVersion: 2.6.33
Contact: netdev@vger.kernel.org
Description:
Indicates the interface latest or current speed value. Value is
an integer representing the link speed in Mbits/sec.
Note: this attribute is only valid for interfaces that implement
the ethtool get_settings method (mostly Ethernet ).
What: /sys/class/net/<iface>/tx_queue_len
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Indicates the interface transmit queue len in number of packets,
as an integer value. Value depend on the type of interface,
Ethernet network adapters have a default value of 1000 unless
configured otherwise
What: /sys/class/net/<iface>/type
Date: April 2005
KernelVersion: 2.6.12
Contact: netdev@vger.kernel.org
Description:
Indicates the interface protocol type as a decimal value. See
include/uapi/linux/if_arp.h for all possible values.
What: /sys/class/net/<iface>/phys_switch_id
Date: November 2014
KernelVersion: 3.19
Contact: netdev@vger.kernel.org
Description:
Indicates the unique physical switch identifier of a switch this
port belongs to, as a string.