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can: Add documentation for virtual CAN driver usage

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This patch adds a usage documentation for the virtual CAN driver (vcan).

Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Oliver Hartkopp 2008-09-23 14:53:14 -07:00 committed by David S. Miller
parent 28e3487b7d
commit e5d2304802
1 changed files with 40 additions and 4 deletions
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44
Documentation/networking/can.txt
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@ -35,8 +35,9 @@ This file contains
6.1 general settings
6.2 local loopback of sent frames
6.3 CAN controller hardware filters
6.4 currently supported CAN hardware
6.5 todo
6.4 The virtual CAN driver (vcan)
6.5 currently supported CAN hardware
6.6 todo
7 Credits
@ -584,7 +585,42 @@ solution for a couple of reasons:
@133MHz with four SJA1000 CAN controllers from 2002 under heavy bus
load without any problems ...
6.4 currently supported CAN hardware (September 2007)
6.4 The virtual CAN driver (vcan)
Similar to the network loopback devices, vcan offers a virtual local
CAN interface. A full qualified address on CAN consists of
- a unique CAN Identifier (CAN ID)
- the CAN bus this CAN ID is transmitted on (e.g. can0)
so in common use cases more than one virtual CAN interface is needed.
The virtual CAN interfaces allow the transmission and reception of CAN
frames without real CAN controller hardware. Virtual CAN network
devices are usually named 'vcanX', like vcan0 vcan1 vcan2 ...
When compiled as a module the virtual CAN driver module is called vcan.ko
Since Linux Kernel version 2.6.24 the vcan driver supports the Kernel
netlink interface to create vcan network devices. The creation and
removal of vcan network devices can be managed with the ip(8) tool:
- Create a virtual CAN network interface:
ip link add type vcan
- Create a virtual CAN network interface with a specific name 'vcan42':
ip link add dev vcan42 type vcan
- Remove a (virtual CAN) network interface 'vcan42':
ip link del vcan42
The tool 'vcan' from the SocketCAN SVN repository on BerliOS is obsolete.
Virtual CAN network device creation in older Kernels:
In Linux Kernel versions < 2.6.24 the vcan driver creates 4 vcan
netdevices at module load time by default. This value can be changed
with the module parameter 'numdev'. E.g. 'modprobe vcan numdev=8'
6.5 currently supported CAN hardware
On the project website http://developer.berlios.de/projects/socketcan
there are different drivers available:
@ -603,7 +639,7 @@ solution for a couple of reasons:
Please check the Mailing Lists on the berlios OSS project website.
6.5 todo (September 2007)
6.6 todo
The configuration interface for CAN network drivers is still an open
issue that has not been finalized in the socketcan project. Also the