NAME
ng_device —
device netgraph node type
SYNOPSIS
#include
<netgraph/ng_device.h>
DESCRIPTION
A device node is both a netgraph node and
a system device interface. When a device node is
created, a new device entry appears which is accessible via the regular file
operators such as
open(2),
close(2),
read(2),
write(2), etc.
The first node is created as /dev/ngd0, subsequent nodes are /dev/ngd1, /dev/ngd2, etc.
HOOKS
A device node has a single hook with an
arbitrary name. All data coming in over the hook will be presented to the
device for
read(2). All data coming in from the device entry by
write(2) will be forwarded to the hook.
CONTROL MESSAGES
The device node supports the generic
control messages, plus the following:
NGM_DEVICE_GET_DEVNAME- Returns the device name corresponding to the node.
NGM_DEVICE_ETHERALIGN- Apply the system ETHER_ALIGN offset to mbufs sent out the node's hook, if running on an architecture that requires strict alignment. Use this option when the data being injected via the device node ultimately ends up being fed into the protocol stack as ethernet packets (e.g., via an ng_eiface(4) node).
SHUTDOWN
This node shuts down upon receipt of a
NGM_SHUTDOWN control message, or upon hook
disconnection. The associated device entry is removed and becomes available
for use by future device nodes.
SEE ALSO
HISTORY
The device node type was first implemented
in FreeBSD 5.0.
AUTHORS
Mark Santcroos
<marks@ripe.net>
Gleb Smirnoff
<glebius@FreeBSD.org>