602 lines
27 KiB
Plaintext
602 lines
27 KiB
Plaintext
Distributed Switch Architecture
|
|
===============================
|
|
|
|
Introduction
|
|
============
|
|
|
|
This document describes the Distributed Switch Architecture (DSA) subsystem
|
|
design principles, limitations, interactions with other subsystems, and how to
|
|
develop drivers for this subsystem as well as a TODO for developers interested
|
|
in joining the effort.
|
|
|
|
Design principles
|
|
=================
|
|
|
|
The Distributed Switch Architecture is a subsystem which was primarily designed
|
|
to support Marvell Ethernet switches (MV88E6xxx, a.k.a Linkstreet product line)
|
|
using Linux, but has since evolved to support other vendors as well.
|
|
|
|
The original philosophy behind this design was to be able to use unmodified
|
|
Linux tools such as bridge, iproute2, ifconfig to work transparently whether
|
|
they configured/queried a switch port network device or a regular network
|
|
device.
|
|
|
|
An Ethernet switch is typically comprised of multiple front-panel ports, and one
|
|
or more CPU or management port. The DSA subsystem currently relies on the
|
|
presence of a management port connected to an Ethernet controller capable of
|
|
receiving Ethernet frames from the switch. This is a very common setup for all
|
|
kinds of Ethernet switches found in Small Home and Office products: routers,
|
|
gateways, or even top-of-the rack switches. This host Ethernet controller will
|
|
be later referred to as "master" and "cpu" in DSA terminology and code.
|
|
|
|
The D in DSA stands for Distributed, because the subsystem has been designed
|
|
with the ability to configure and manage cascaded switches on top of each other
|
|
using upstream and downstream Ethernet links between switches. These specific
|
|
ports are referred to as "dsa" ports in DSA terminology and code. A collection
|
|
of multiple switches connected to each other is called a "switch tree".
|
|
|
|
For each front-panel port, DSA will create specialized network devices which are
|
|
used as controlling and data-flowing endpoints for use by the Linux networking
|
|
stack. These specialized network interfaces are referred to as "slave" network
|
|
interfaces in DSA terminology and code.
|
|
|
|
The ideal case for using DSA is when an Ethernet switch supports a "switch tag"
|
|
which is a hardware feature making the switch insert a specific tag for each
|
|
Ethernet frames it received to/from specific ports to help the management
|
|
interface figure out:
|
|
|
|
- what port is this frame coming from
|
|
- what was the reason why this frame got forwarded
|
|
- how to send CPU originated traffic to specific ports
|
|
|
|
The subsystem does support switches not capable of inserting/stripping tags, but
|
|
the features might be slightly limited in that case (traffic separation relies
|
|
on Port-based VLAN IDs).
|
|
|
|
Note that DSA does not currently create network interfaces for the "cpu" and
|
|
"dsa" ports because:
|
|
|
|
- the "cpu" port is the Ethernet switch facing side of the management
|
|
controller, and as such, would create a duplication of feature, since you
|
|
would get two interfaces for the same conduit: master netdev, and "cpu" netdev
|
|
|
|
- the "dsa" port(s) are just conduits between two or more switches, and as such
|
|
cannot really be used as proper network interfaces either, only the
|
|
downstream, or the top-most upstream interface makes sense with that model
|
|
|
|
Switch tagging protocols
|
|
------------------------
|
|
|
|
DSA currently supports 5 different tagging protocols, and a tag-less mode as
|
|
well. The different protocols are implemented in:
|
|
|
|
net/dsa/tag_trailer.c: Marvell's 4 trailer tag mode (legacy)
|
|
net/dsa/tag_dsa.c: Marvell's original DSA tag
|
|
net/dsa/tag_edsa.c: Marvell's enhanced DSA tag
|
|
net/dsa/tag_brcm.c: Broadcom's 4 bytes tag
|
|
net/dsa/tag_qca.c: Qualcomm's 2 bytes tag
|
|
|
|
The exact format of the tag protocol is vendor specific, but in general, they
|
|
all contain something which:
|
|
|
|
- identifies which port the Ethernet frame came from/should be sent to
|
|
- provides a reason why this frame was forwarded to the management interface
|
|
|
|
Master network devices
|
|
----------------------
|
|
|
|
Master network devices are regular, unmodified Linux network device drivers for
|
|
the CPU/management Ethernet interface. Such a driver might occasionally need to
|
|
know whether DSA is enabled (e.g.: to enable/disable specific offload features),
|
|
but the DSA subsystem has been proven to work with industry standard drivers:
|
|
e1000e, mv643xx_eth etc. without having to introduce modifications to these
|
|
drivers. Such network devices are also often referred to as conduit network
|
|
devices since they act as a pipe between the host processor and the hardware
|
|
Ethernet switch.
|
|
|
|
Networking stack hooks
|
|
----------------------
|
|
|
|
When a master netdev is used with DSA, a small hook is placed in in the
|
|
networking stack is in order to have the DSA subsystem process the Ethernet
|
|
switch specific tagging protocol. DSA accomplishes this by registering a
|
|
specific (and fake) Ethernet type (later becoming skb->protocol) with the
|
|
networking stack, this is also known as a ptype or packet_type. A typical
|
|
Ethernet Frame receive sequence looks like this:
|
|
|
|
Master network device (e.g.: e1000e):
|
|
|
|
Receive interrupt fires:
|
|
- receive function is invoked
|
|
- basic packet processing is done: getting length, status etc.
|
|
- packet is prepared to be processed by the Ethernet layer by calling
|
|
eth_type_trans
|
|
|
|
net/ethernet/eth.c:
|
|
|
|
eth_type_trans(skb, dev)
|
|
if (dev->dsa_ptr != NULL)
|
|
-> skb->protocol = ETH_P_XDSA
|
|
|
|
drivers/net/ethernet/*:
|
|
|
|
netif_receive_skb(skb)
|
|
-> iterate over registered packet_type
|
|
-> invoke handler for ETH_P_XDSA, calls dsa_switch_rcv()
|
|
|
|
net/dsa/dsa.c:
|
|
-> dsa_switch_rcv()
|
|
-> invoke switch tag specific protocol handler in
|
|
net/dsa/tag_*.c
|
|
|
|
net/dsa/tag_*.c:
|
|
-> inspect and strip switch tag protocol to determine originating port
|
|
-> locate per-port network device
|
|
-> invoke eth_type_trans() with the DSA slave network device
|
|
-> invoked netif_receive_skb()
|
|
|
|
Past this point, the DSA slave network devices get delivered regular Ethernet
|
|
frames that can be processed by the networking stack.
|
|
|
|
Slave network devices
|
|
---------------------
|
|
|
|
Slave network devices created by DSA are stacked on top of their master network
|
|
device, each of these network interfaces will be responsible for being a
|
|
controlling and data-flowing end-point for each front-panel port of the switch.
|
|
These interfaces are specialized in order to:
|
|
|
|
- insert/remove the switch tag protocol (if it exists) when sending traffic
|
|
to/from specific switch ports
|
|
- query the switch for ethtool operations: statistics, link state,
|
|
Wake-on-LAN, register dumps...
|
|
- external/internal PHY management: link, auto-negotiation etc.
|
|
|
|
These slave network devices have custom net_device_ops and ethtool_ops function
|
|
pointers which allow DSA to introduce a level of layering between the networking
|
|
stack/ethtool, and the switch driver implementation.
|
|
|
|
Upon frame transmission from these slave network devices, DSA will look up which
|
|
switch tagging protocol is currently registered with these network devices, and
|
|
invoke a specific transmit routine which takes care of adding the relevant
|
|
switch tag in the Ethernet frames.
|
|
|
|
These frames are then queued for transmission using the master network device
|
|
ndo_start_xmit() function, since they contain the appropriate switch tag, the
|
|
Ethernet switch will be able to process these incoming frames from the
|
|
management interface and delivers these frames to the physical switch port.
|
|
|
|
Graphical representation
|
|
------------------------
|
|
|
|
Summarized, this is basically how DSA looks like from a network device
|
|
perspective:
|
|
|
|
|
|
|---------------------------
|
|
| CPU network device (eth0)|
|
|
----------------------------
|
|
| <tag added by switch |
|
|
| |
|
|
| |
|
|
| tag added by CPU> |
|
|
|--------------------------------------------|
|
|
| Switch driver |
|
|
|--------------------------------------------|
|
|
|| || ||
|
|
|-------| |-------| |-------|
|
|
| sw0p0 | | sw0p1 | | sw0p2 |
|
|
|-------| |-------| |-------|
|
|
|
|
Slave MDIO bus
|
|
--------------
|
|
|
|
In order to be able to read to/from a switch PHY built into it, DSA creates a
|
|
slave MDIO bus which allows a specific switch driver to divert and intercept
|
|
MDIO reads/writes towards specific PHY addresses. In most MDIO-connected
|
|
switches, these functions would utilize direct or indirect PHY addressing mode
|
|
to return standard MII registers from the switch builtin PHYs, allowing the PHY
|
|
library and/or to return link status, link partner pages, auto-negotiation
|
|
results etc..
|
|
|
|
For Ethernet switches which have both external and internal MDIO busses, the
|
|
slave MII bus can be utilized to mux/demux MDIO reads and writes towards either
|
|
internal or external MDIO devices this switch might be connected to: internal
|
|
PHYs, external PHYs, or even external switches.
|
|
|
|
Data structures
|
|
---------------
|
|
|
|
DSA data structures are defined in include/net/dsa.h as well as
|
|
net/dsa/dsa_priv.h.
|
|
|
|
dsa_chip_data: platform data configuration for a given switch device, this
|
|
structure describes a switch device's parent device, its address, as well as
|
|
various properties of its ports: names/labels, and finally a routing table
|
|
indication (when cascading switches)
|
|
|
|
dsa_platform_data: platform device configuration data which can reference a
|
|
collection of dsa_chip_data structure if multiples switches are cascaded, the
|
|
master network device this switch tree is attached to needs to be referenced
|
|
|
|
dsa_switch_tree: structure assigned to the master network device under
|
|
"dsa_ptr", this structure references a dsa_platform_data structure as well as
|
|
the tagging protocol supported by the switch tree, and which receive/transmit
|
|
function hooks should be invoked, information about the directly attached switch
|
|
is also provided: CPU port. Finally, a collection of dsa_switch are referenced
|
|
to address individual switches in the tree.
|
|
|
|
dsa_switch: structure describing a switch device in the tree, referencing a
|
|
dsa_switch_tree as a backpointer, slave network devices, master network device,
|
|
and a reference to the backing dsa_switch_ops
|
|
|
|
dsa_switch_ops: structure referencing function pointers, see below for a full
|
|
description.
|
|
|
|
Design limitations
|
|
==================
|
|
|
|
DSA is a platform device driver
|
|
-------------------------------
|
|
|
|
DSA is implemented as a DSA platform device driver which is convenient because
|
|
it will register the entire DSA switch tree attached to a master network device
|
|
in one-shot, facilitating the device creation and simplifying the device driver
|
|
model a bit, this comes however with a number of limitations:
|
|
|
|
- building DSA and its switch drivers as modules is currently not working
|
|
- the device driver parenting does not necessarily reflect the original
|
|
bus/device the switch can be created from
|
|
- supporting non-MDIO and non-MMIO (platform) switches is not possible
|
|
|
|
Limits on the number of devices and ports
|
|
-----------------------------------------
|
|
|
|
DSA currently limits the number of maximum switches within a tree to 4
|
|
(DSA_MAX_SWITCHES), and the number of ports per switch to 12 (DSA_MAX_PORTS).
|
|
These limits could be extended to support larger configurations would this need
|
|
arise.
|
|
|
|
Lack of CPU/DSA network devices
|
|
-------------------------------
|
|
|
|
DSA does not currently create slave network devices for the CPU or DSA ports, as
|
|
described before. This might be an issue in the following cases:
|
|
|
|
- inability to fetch switch CPU port statistics counters using ethtool, which
|
|
can make it harder to debug MDIO switch connected using xMII interfaces
|
|
|
|
- inability to configure the CPU port link parameters based on the Ethernet
|
|
controller capabilities attached to it: http://patchwork.ozlabs.org/patch/509806/
|
|
|
|
- inability to configure specific VLAN IDs / trunking VLANs between switches
|
|
when using a cascaded setup
|
|
|
|
Common pitfalls using DSA setups
|
|
--------------------------------
|
|
|
|
Once a master network device is configured to use DSA (dev->dsa_ptr becomes
|
|
non-NULL), and the switch behind it expects a tagging protocol, this network
|
|
interface can only exclusively be used as a conduit interface. Sending packets
|
|
directly through this interface (e.g.: opening a socket using this interface)
|
|
will not make us go through the switch tagging protocol transmit function, so
|
|
the Ethernet switch on the other end, expecting a tag will typically drop this
|
|
frame.
|
|
|
|
Slave network devices check that the master network device is UP before allowing
|
|
you to administratively bring UP these slave network devices. A common
|
|
configuration mistake is forgetting to bring UP the master network device first.
|
|
|
|
Interactions with other subsystems
|
|
==================================
|
|
|
|
DSA currently leverages the following subsystems:
|
|
|
|
- MDIO/PHY library: drivers/net/phy/phy.c, mdio_bus.c
|
|
- Switchdev: net/switchdev/*
|
|
- Device Tree for various of_* functions
|
|
|
|
MDIO/PHY library
|
|
----------------
|
|
|
|
Slave network devices exposed by DSA may or may not be interfacing with PHY
|
|
devices (struct phy_device as defined in include/linux/phy.h), but the DSA
|
|
subsystem deals with all possible combinations:
|
|
|
|
- internal PHY devices, built into the Ethernet switch hardware
|
|
- external PHY devices, connected via an internal or external MDIO bus
|
|
- internal PHY devices, connected via an internal MDIO bus
|
|
- special, non-autonegotiated or non MDIO-managed PHY devices: SFPs, MoCA; a.k.a
|
|
fixed PHYs
|
|
|
|
The PHY configuration is done by the dsa_slave_phy_setup() function and the
|
|
logic basically looks like this:
|
|
|
|
- if Device Tree is used, the PHY device is looked up using the standard
|
|
"phy-handle" property, if found, this PHY device is created and registered
|
|
using of_phy_connect()
|
|
|
|
- if Device Tree is used, and the PHY device is "fixed", that is, conforms to
|
|
the definition of a non-MDIO managed PHY as defined in
|
|
Documentation/devicetree/bindings/net/fixed-link.txt, the PHY is registered
|
|
and connected transparently using the special fixed MDIO bus driver
|
|
|
|
- finally, if the PHY is built into the switch, as is very common with
|
|
standalone switch packages, the PHY is probed using the slave MII bus created
|
|
by DSA
|
|
|
|
|
|
SWITCHDEV
|
|
---------
|
|
|
|
DSA directly utilizes SWITCHDEV when interfacing with the bridge layer, and
|
|
more specifically with its VLAN filtering portion when configuring VLANs on top
|
|
of per-port slave network devices. Since DSA primarily deals with
|
|
MDIO-connected switches, although not exclusively, SWITCHDEV's
|
|
prepare/abort/commit phases are often simplified into a prepare phase which
|
|
checks whether the operation is supported by the DSA switch driver, and a commit
|
|
phase which applies the changes.
|
|
|
|
As of today, the only SWITCHDEV objects supported by DSA are the FDB and VLAN
|
|
objects.
|
|
|
|
Device Tree
|
|
-----------
|
|
|
|
DSA features a standardized binding which is documented in
|
|
Documentation/devicetree/bindings/net/dsa/dsa.txt. PHY/MDIO library helper
|
|
functions such as of_get_phy_mode(), of_phy_connect() are also used to query
|
|
per-port PHY specific details: interface connection, MDIO bus location etc..
|
|
|
|
Driver development
|
|
==================
|
|
|
|
DSA switch drivers need to implement a dsa_switch_ops structure which will
|
|
contain the various members described below.
|
|
|
|
register_switch_driver() registers this dsa_switch_ops in its internal list
|
|
of drivers to probe for. unregister_switch_driver() does the exact opposite.
|
|
|
|
Unless requested differently by setting the priv_size member accordingly, DSA
|
|
does not allocate any driver private context space.
|
|
|
|
Switch configuration
|
|
--------------------
|
|
|
|
- tag_protocol: this is to indicate what kind of tagging protocol is supported,
|
|
should be a valid value from the dsa_tag_protocol enum
|
|
|
|
- probe: probe routine which will be invoked by the DSA platform device upon
|
|
registration to test for the presence/absence of a switch device. For MDIO
|
|
devices, it is recommended to issue a read towards internal registers using
|
|
the switch pseudo-PHY and return whether this is a supported device. For other
|
|
buses, return a non-NULL string
|
|
|
|
- setup: setup function for the switch, this function is responsible for setting
|
|
up the dsa_switch_ops private structure with all it needs: register maps,
|
|
interrupts, mutexes, locks etc.. This function is also expected to properly
|
|
configure the switch to separate all network interfaces from each other, that
|
|
is, they should be isolated by the switch hardware itself, typically by creating
|
|
a Port-based VLAN ID for each port and allowing only the CPU port and the
|
|
specific port to be in the forwarding vector. Ports that are unused by the
|
|
platform should be disabled. Past this function, the switch is expected to be
|
|
fully configured and ready to serve any kind of request. It is recommended
|
|
to issue a software reset of the switch during this setup function in order to
|
|
avoid relying on what a previous software agent such as a bootloader/firmware
|
|
may have previously configured.
|
|
|
|
PHY devices and link management
|
|
-------------------------------
|
|
|
|
- get_phy_flags: Some switches are interfaced to various kinds of Ethernet PHYs,
|
|
if the PHY library PHY driver needs to know about information it cannot obtain
|
|
on its own (e.g.: coming from switch memory mapped registers), this function
|
|
should return a 32-bits bitmask of "flags", that is private between the switch
|
|
driver and the Ethernet PHY driver in drivers/net/phy/*.
|
|
|
|
- phy_read: Function invoked by the DSA slave MDIO bus when attempting to read
|
|
the switch port MDIO registers. If unavailable, return 0xffff for each read.
|
|
For builtin switch Ethernet PHYs, this function should allow reading the link
|
|
status, auto-negotiation results, link partner pages etc..
|
|
|
|
- phy_write: Function invoked by the DSA slave MDIO bus when attempting to write
|
|
to the switch port MDIO registers. If unavailable return a negative error
|
|
code.
|
|
|
|
- adjust_link: Function invoked by the PHY library when a slave network device
|
|
is attached to a PHY device. This function is responsible for appropriately
|
|
configuring the switch port link parameters: speed, duplex, pause based on
|
|
what the phy_device is providing.
|
|
|
|
- fixed_link_update: Function invoked by the PHY library, and specifically by
|
|
the fixed PHY driver asking the switch driver for link parameters that could
|
|
not be auto-negotiated, or obtained by reading the PHY registers through MDIO.
|
|
This is particularly useful for specific kinds of hardware such as QSGMII,
|
|
MoCA or other kinds of non-MDIO managed PHYs where out of band link
|
|
information is obtained
|
|
|
|
Ethtool operations
|
|
------------------
|
|
|
|
- get_strings: ethtool function used to query the driver's strings, will
|
|
typically return statistics strings, private flags strings etc.
|
|
|
|
- get_ethtool_stats: ethtool function used to query per-port statistics and
|
|
return their values. DSA overlays slave network devices general statistics:
|
|
RX/TX counters from the network device, with switch driver specific statistics
|
|
per port
|
|
|
|
- get_sset_count: ethtool function used to query the number of statistics items
|
|
|
|
- get_wol: ethtool function used to obtain Wake-on-LAN settings per-port, this
|
|
function may, for certain implementations also query the master network device
|
|
Wake-on-LAN settings if this interface needs to participate in Wake-on-LAN
|
|
|
|
- set_wol: ethtool function used to configure Wake-on-LAN settings per-port,
|
|
direct counterpart to set_wol with similar restrictions
|
|
|
|
- set_eee: ethtool function which is used to configure a switch port EEE (Green
|
|
Ethernet) settings, can optionally invoke the PHY library to enable EEE at the
|
|
PHY level if relevant. This function should enable EEE at the switch port MAC
|
|
controller and data-processing logic
|
|
|
|
- get_eee: ethtool function which is used to query a switch port EEE settings,
|
|
this function should return the EEE state of the switch port MAC controller
|
|
and data-processing logic as well as query the PHY for its currently configured
|
|
EEE settings
|
|
|
|
- get_eeprom_len: ethtool function returning for a given switch the EEPROM
|
|
length/size in bytes
|
|
|
|
- get_eeprom: ethtool function returning for a given switch the EEPROM contents
|
|
|
|
- set_eeprom: ethtool function writing specified data to a given switch EEPROM
|
|
|
|
- get_regs_len: ethtool function returning the register length for a given
|
|
switch
|
|
|
|
- get_regs: ethtool function returning the Ethernet switch internal register
|
|
contents. This function might require user-land code in ethtool to
|
|
pretty-print register values and registers
|
|
|
|
Power management
|
|
----------------
|
|
|
|
- suspend: function invoked by the DSA platform device when the system goes to
|
|
suspend, should quiesce all Ethernet switch activities, but keep ports
|
|
participating in Wake-on-LAN active as well as additional wake-up logic if
|
|
supported
|
|
|
|
- resume: function invoked by the DSA platform device when the system resumes,
|
|
should resume all Ethernet switch activities and re-configure the switch to be
|
|
in a fully active state
|
|
|
|
- port_enable: function invoked by the DSA slave network device ndo_open
|
|
function when a port is administratively brought up, this function should be
|
|
fully enabling a given switch port. DSA takes care of marking the port with
|
|
BR_STATE_BLOCKING if the port is a bridge member, or BR_STATE_FORWARDING if it
|
|
was not, and propagating these changes down to the hardware
|
|
|
|
- port_disable: function invoked by the DSA slave network device ndo_close
|
|
function when a port is administratively brought down, this function should be
|
|
fully disabling a given switch port. DSA takes care of marking the port with
|
|
BR_STATE_DISABLED and propagating changes to the hardware if this port is
|
|
disabled while being a bridge member
|
|
|
|
Bridge layer
|
|
------------
|
|
|
|
- port_bridge_join: bridge layer function invoked when a given switch port is
|
|
added to a bridge, this function should be doing the necessary at the switch
|
|
level to permit the joining port from being added to the relevant logical
|
|
domain for it to ingress/egress traffic with other members of the bridge.
|
|
|
|
- port_bridge_leave: bridge layer function invoked when a given switch port is
|
|
removed from a bridge, this function should be doing the necessary at the
|
|
switch level to deny the leaving port from ingress/egress traffic from the
|
|
remaining bridge members. When the port leaves the bridge, it should be aged
|
|
out at the switch hardware for the switch to (re) learn MAC addresses behind
|
|
this port.
|
|
|
|
- port_stp_state_set: bridge layer function invoked when a given switch port STP
|
|
state is computed by the bridge layer and should be propagated to switch
|
|
hardware to forward/block/learn traffic. The switch driver is responsible for
|
|
computing a STP state change based on current and asked parameters and perform
|
|
the relevant ageing based on the intersection results
|
|
|
|
Bridge VLAN filtering
|
|
---------------------
|
|
|
|
- port_vlan_filtering: bridge layer function invoked when the bridge gets
|
|
configured for turning on or off VLAN filtering. If nothing specific needs to
|
|
be done at the hardware level, this callback does not need to be implemented.
|
|
When VLAN filtering is turned on, the hardware must be programmed with
|
|
rejecting 802.1Q frames which have VLAN IDs outside of the programmed allowed
|
|
VLAN ID map/rules. If there is no PVID programmed into the switch port,
|
|
untagged frames must be rejected as well. When turned off the switch must
|
|
accept any 802.1Q frames irrespective of their VLAN ID, and untagged frames are
|
|
allowed.
|
|
|
|
- port_vlan_prepare: bridge layer function invoked when the bridge prepares the
|
|
configuration of a VLAN on the given port. If the operation is not supported
|
|
by the hardware, this function should return -EOPNOTSUPP to inform the bridge
|
|
code to fallback to a software implementation. No hardware setup must be done
|
|
in this function. See port_vlan_add for this and details.
|
|
|
|
- port_vlan_add: bridge layer function invoked when a VLAN is configured
|
|
(tagged or untagged) for the given switch port
|
|
|
|
- port_vlan_del: bridge layer function invoked when a VLAN is removed from the
|
|
given switch port
|
|
|
|
- port_vlan_dump: bridge layer function invoked with a switchdev callback
|
|
function that the driver has to call for each VLAN the given port is a member
|
|
of. A switchdev object is used to carry the VID and bridge flags.
|
|
|
|
- port_fdb_prepare: bridge layer function invoked when the bridge prepares the
|
|
installation of a Forwarding Database entry. If the operation is not
|
|
supported, this function should return -EOPNOTSUPP to inform the bridge code
|
|
to fallback to a software implementation. No hardware setup must be done in
|
|
this function. See port_fdb_add for this and details.
|
|
|
|
- port_fdb_add: bridge layer function invoked when the bridge wants to install a
|
|
Forwarding Database entry, the switch hardware should be programmed with the
|
|
specified address in the specified VLAN Id in the forwarding database
|
|
associated with this VLAN ID
|
|
|
|
Note: VLAN ID 0 corresponds to the port private database, which, in the context
|
|
of DSA, would be the its port-based VLAN, used by the associated bridge device.
|
|
|
|
- port_fdb_del: bridge layer function invoked when the bridge wants to remove a
|
|
Forwarding Database entry, the switch hardware should be programmed to delete
|
|
the specified MAC address from the specified VLAN ID if it was mapped into
|
|
this port forwarding database
|
|
|
|
- port_fdb_dump: bridge layer function invoked with a switchdev callback
|
|
function that the driver has to call for each MAC address known to be behind
|
|
the given port. A switchdev object is used to carry the VID and FDB info.
|
|
|
|
- port_mdb_prepare: bridge layer function invoked when the bridge prepares the
|
|
installation of a multicast database entry. If the operation is not supported,
|
|
this function should return -EOPNOTSUPP to inform the bridge code to fallback
|
|
to a software implementation. No hardware setup must be done in this function.
|
|
See port_fdb_add for this and details.
|
|
|
|
- port_mdb_add: bridge layer function invoked when the bridge wants to install
|
|
a multicast database entry, the switch hardware should be programmed with the
|
|
specified address in the specified VLAN ID in the forwarding database
|
|
associated with this VLAN ID.
|
|
|
|
Note: VLAN ID 0 corresponds to the port private database, which, in the context
|
|
of DSA, would be the its port-based VLAN, used by the associated bridge device.
|
|
|
|
- port_mdb_del: bridge layer function invoked when the bridge wants to remove a
|
|
multicast database entry, the switch hardware should be programmed to delete
|
|
the specified MAC address from the specified VLAN ID if it was mapped into
|
|
this port forwarding database.
|
|
|
|
- port_mdb_dump: bridge layer function invoked with a switchdev callback
|
|
function that the driver has to call for each MAC address known to be behind
|
|
the given port. A switchdev object is used to carry the VID and MDB info.
|
|
|
|
TODO
|
|
====
|
|
|
|
Making SWITCHDEV and DSA converge towards an unified codebase
|
|
-------------------------------------------------------------
|
|
|
|
SWITCHDEV properly takes care of abstracting the networking stack with offload
|
|
capable hardware, but does not enforce a strict switch device driver model. On
|
|
the other DSA enforces a fairly strict device driver model, and deals with most
|
|
of the switch specific. At some point we should envision a merger between these
|
|
two subsystems and get the best of both worlds.
|
|
|
|
Other hanging fruits
|
|
--------------------
|
|
|
|
- making the number of ports fully dynamic and not dependent on DSA_MAX_PORTS
|
|
- allowing more than one CPU/management interface:
|
|
http://comments.gmane.org/gmane.linux.network/365657
|
|
- porting more drivers from other vendors:
|
|
http://comments.gmane.org/gmane.linux.network/365510
|