freebsd-nq/share/man/man4/devctl.4

.\"
.\" Copyright (c) 2002 M. Warner Losh
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. The name of the author may not be used to endorse or promote products
.\"    derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd February 11, 2003
.Dt DEVCTL 4
.Os
.Sh NAME
.Nm devctl
.Nd "device event reporting and device control interface"
.Sh DESCRIPTION
The
.Nm
device is used to report device events from the kernel.
Future versions will allow for some device control as well.
.Sh IMPLEMENTATION NOTES
This design allows only one reader for
.Pa /dev/devctl .
This is not desirable
in the long run, but will get a lot of hair out of this implementation.
Maybe we should make this device a clonable device.
.Pp
Also note: we specifically do not attach a device to the
.Vt device_t
tree
to avoid potential chicken and egg problems.
One could argue that all of this belongs to the root node.
One could also further argue that the
.Xr sysctl 3
interface that we have now might more properly be an
.Xr ioctl 2
interface.
.Pp
.Dv SIGIO
support is included in the driver.
However, the author is not sure that the
.Dv SIGIO
support is done correctly.
It was copied from a driver that had
.Dv SIGIO
support that likely has not been
tested since
.Fx 3.4
or
.Fx 2.2.8 !
.Pp
The read channel for this device is used to report changes to
userland in realtime.
We return one record at a time.
If you try to read this device a character at a time, you will lose
the rest of the data.
Listening programs are expected to cope.
.Pp
The sysctl and boot parameter
.Va hw.bus.devctl_disable
is used to disable
.Nm
when no
.Xr devd 8
is running.
.Sh PROTOCOL
The
.Nm
device
uses an
.Tn ASCII
protocol.
The driver returns one record at a time to its readers.
Each record is terminated with a newline.
The first character of the record is the event type.
.Pp
.Bl -column -compact "Type" "Description"
.Em "Type	Description"
!	A notify event, such as a link state change.
+	Device node in tree attached.
-	Device node in tree detached.
?	Unknown device detected.
.El
.Ss Message Formats
Except for the first character in the record, attach and detach
messages have the same format.
.Pp
.D1 Ar T Ns Ar dev Li at Ar parent Li on Ar location
.Pp
.Bl -column -compact "location" "Description"
.Em "Part	Description"
.It Ar T Ta "+ or -"
.It Ar dev Ta "The device name that was attached/detached."
.It Ar parent Ta "The device name of the parent bus that attached the device."
.It Ar location Ta "Bus specific location information."
.El
.Pp
The nomatch messages can be used to load devices driver.
If you load a device driver, then one of two things can happen.
If the device driver attaches to something, you will get a device
attached message.
If it does not, then nothing will happen.
.Pp
The attach and detach messages arrive after the event.
This means one cannot use the attach message to load an alternate
driver.
The attach message driver has already claimed this device.
One cannot use the detach messages to flush data to the device.
The device is already gone.
.Sh SEE ALSO
.Xr devd 8
Add a rudimentary man page for /dev/devctl. Approved by: re (blanket devd) 2002-12-11 23:08:19 +00:00			`.\"`
			`.\" Copyright (c) 2002 M. Warner Losh`
			`.\" All rights reserved.`
			`.\"`
			`.\" Redistribution and use in source and binary forms, with or without`
			`.\" modification, are permitted provided that the following conditions`
			`.\" are met:`
			`.\" 1. Redistributions of source code must retain the above copyright`
			`.\" notice, this list of conditions and the following disclaimer.`
			`.\" 2. The name of the author may not be used to endorse or promote products`
			`.\" derived from this software without specific prior written permission.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
			`.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE`
			`.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE`
			`.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE`
			`.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL`
			`.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS`
			`.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)`
			`.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT`
			`.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY`
			`.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF`
			`.\" SUCH DAMAGE.`
			`.\"`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`.\" $FreeBSD$`
Add a rudimentary man page for /dev/devctl. Approved by: re (blanket devd) 2002-12-11 23:08:19 +00:00			`.\"`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.Dd February 11, 2003`
Add a rudimentary man page for /dev/devctl. Approved by: re (blanket devd) 2002-12-11 23:08:19 +00:00			`.Dt DEVCTL 4`
			`.Os`
			`.Sh NAME`
			`.Nm devctl`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`.Nd "device event reporting and device control interface"`
Add a rudimentary man page for /dev/devctl. Approved by: re (blanket devd) 2002-12-11 23:08:19 +00:00			`.Sh DESCRIPTION`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`The`
			`.Nm`
			`device is used to report device events from the kernel.`
			`Future versions will allow for some device control as well.`
			`.Sh IMPLEMENTATION NOTES`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`This design allows only one reader for`
			`.Pa /dev/devctl .`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`This is not desirable`
			`in the long run, but will get a lot of hair out of this implementation.`
			`Maybe we should make this device a clonable device.`
			`.Pp`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`Also note: we specifically do not attach a device to the`
			`.Vt device_t`
			`tree`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`to avoid potential chicken and egg problems.`
			`One could argue that all of this belongs to the root node.`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`One could also further argue that the`
			`.Xr sysctl 3`
			`interface that we have now might more properly be an`
			`.Xr ioctl 2`
			`interface.`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.Pp`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`.Dv SIGIO`
			`support is included in the driver.`
			`However, the author is not sure that the`
			`.Dv SIGIO`
			`support is done correctly.`
			`It was copied from a driver that had`
			`.Dv SIGIO`
			`support that likely has not been`
			`tested since`
			`.Fx 3.4`
			`or`
			`.Fx 2.2.8 !`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.Pp`
			`The read channel for this device is used to report changes to`
			`userland in realtime.`
			`We return one record at a time.`
Commit the results of the typo hunt by Darren Pilgrim. This change affects documentation and comments only, no real code involved. PR: misc/101245 Submitted by: Darren Pilgrim <darren pilgrim bitfreak org> Tested by: md5(1) MFC after: 1 week 2006-08-04 07:56:35 +00:00			`If you try to read this device a character at a time, you will lose`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`the rest of the data.`
			`Listening programs are expected to cope.`
			`.Pp`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`The sysctl and boot parameter`
			`.Va hw.bus.devctl_disable`
			`is used to disable`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.Nm`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`when no`
			`.Xr devd 8`
			`is running.`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.Sh PROTOCOL`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`The`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.Nm`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`device`
			`uses an`
			`.Tn ASCII`
			`protocol.`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`The driver returns one record at a time to its readers.`
			`Each record is terminated with a newline.`
			`The first character of the record is the event type.`
			`.Pp`
			`.Bl -column -compact "Type" "Description"`
			`.Em "Type Description"`
Add nofification events to the list of event types. PR: docs/88390 Submitted by: Niki Denev <nike_d at cytexbg dot com> Discussed with: Daniel Gerzo <danger at rulez dot sk> MFC After: 8 days 2005-12-30 14:01:01 +00:00			`! A notify event, such as a link state change.`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`+ Device node in tree attached.`
			`- Device node in tree detached.`
			`? Unknown device detected.`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.El`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`.Ss Message Formats`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`Except for the first character in the record, attach and detach`
			`messages have the same format.`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`.Pp`
			`.D1 Ar T Ns Ar dev Li at Ar parent Li on Ar location`
			`.Pp`
			`.Bl -column -compact "location" "Description"`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.Em "Part Description"`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`.It Ar T Ta "+ or -"`
			`.It Ar dev Ta "The device name that was attached/detached."`
			`.It Ar parent Ta "The device name of the parent bus that attached the device."`
			`.It Ar location Ta "Bus specific location information."`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.El`
			`.Pp`
			`The nomatch messages can be used to load devices driver.`
			`If you load a device driver, then one of two things can happen.`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`If the device driver attaches to something, you will get a device`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`attached message.`
mdoc(7) police: Scheduled sweep. 2003-02-24 22:53:26 +00:00			`If it does not, then nothing will happen.`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.Pp`
			`The attach and detach messages arrive after the event.`
			`This means one cannot use the attach message to load an alternate`
			`driver.`
			`The attach message driver has already claimed this device.`
			`One cannot use the detach messages to flush data to the device.`
			`The device is already gone.`
Add a rudimentary man page for /dev/devctl. Approved by: re (blanket devd) 2002-12-11 23:08:19 +00:00			`.Sh SEE ALSO`
Commit a nearly real man page describing the current state of devctl. More work likely needs to happen. This describes things better than the old "this man page intentionally left blank" style man page that I'd committed previously. Nitpickers: comb nits and commit! 2003-02-11 17:36:38 +00:00			`.Xr devd 8`