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Top Forums UNIX for Dummies Questions & Answers how to read or write device files Post 94680 by sriram.ec on Tuesday 3rd of January 2006 04:21:02 AM
Old 01-03-2006
Question how to read or write device files

hi everybody,
i am working in device drivers.As a beginner to this field ,i dont know how to read or write device files. Will copy_to_user and copy_from_user help me?
I have created a device file using mknod command .Can anybody help me in this regard :confused
thanks in advance
sriram
 

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NG_DEVICE(4)						   BSD Kernel Interfaces Manual 					      NG_DEVICE(4)

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, all subsequent nodes /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 one non-generic control message: NGM_DEVICE_GET_DEVNAME Returns device name corresponding to a 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
netgraph(4), ngctl(8) HISTORY
The device node type was first implemented in FreeBSD 5.0. AUTHORS
Mark Santcroos <marks@ripe.net> Gleb Smirnoff <glebius@FreeBSD.org> BSD
October 19, 2004 BSD
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