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devctl(4) [opensolaris man page]

DEVCTL(4)						   BSD Kernel Interfaces Manual 						 DEVCTL(4)

NAME

     devctl -- device event reporting and device control interface

DESCRIPTION

     The devctl device is used to report device events from the kernel.  Future versions will allow for some device control as well.

IMPLEMENTATION NOTES

     This design allows only one reader for /dev/devctl.  This is not desirable in the long run, but will get a lot of hair out of this implemen-
     tation.  Maybe we should make this device a clonable device.

     Also note: we specifically do not attach a device to the 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 sysctl(3) interface that we have now might more properly be an
     ioctl(2) interface.

     SIGIO support is included in the driver.  However, the author is not sure that the SIGIO support is done correctly.  It was copied from a
     driver that had SIGIO support that likely has not been tested since FreeBSD 3.4 or FreeBSD 2.2.8!

     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.

     The sysctl and boot parameter hw.bus.devctl_disable is used to disable devctl when no devd(8) is running.

PROTOCOL

     The devctl device uses an 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.

     Type    Description
     !	     A notify event, such as a link state change.
     +	     Device node in tree attached.
     -	     Device node in tree detached.
     ?	     Unknown device detected.

   Message Formats
     Except for the first character in the record, attach and detach messages have the same format.

	   Tdev at parent on location

     Part	 Description
     T		 + or -
     dev	 The device name that was attached/detached.
     parent	 The device name of the parent bus that attached the device.
     location	 Bus specific location information.

     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.

     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.

SEE ALSO

     devd(8)

BSD
								 February 11, 2003							       BSD

Check Out this Related Man Page

DEVCTL(8)						    BSD System Manager's Manual 						 DEVCTL(8)

NAME

     devctl -- device control utility

SYNOPSIS

     devctl attach device
     devctl detach [-f] device
     devctl disable [-f] device
     devctl enable device
     devctl suspend device
     devctl resume device
     devctl set driver [-f] device driver

DESCRIPTION

     The devctl utility adjusts the state of individual devices in the kernel's internal device hierarchy.  Each invocation of devctl consists of
     a single command followed by command-specific arguments.  Each command operates on a single device specified via the device argument.  The
     device may be specified either as the name of an existing device or as a bus-specific address.  More details on supported address formats can
     be found in devctl(3).

     The following commands are supported:

     attach device
	     Force the kernel to re-probe the device.  If a suitable driver is found, it is attached to the device.

     detach [-f] device
	     Detach the device from its current device driver.	If the -f flag is specified, the device driver will be detached even if the device
	     is busy.

     disable [-f] device
	     Disable a device.	If the device is currently attached to a device driver, the device driver will be detached from the device, but
	     the device will retain its current name.  If the -f flag is specified, the device driver will be detached even if the device is busy.

     enable device
	     Enable a device.  The device will probe and attach if a suitable device driver is found.  Note that this can re-enable a device dis-
	     abled at boot time via a loader tunable.

     suspend device
	     Suspend a device.	This may include placing the device in a reduced power state.

     resume device
	     Resume a suspended device to a fully working state.

     set driver [-f] device driver
	     Force the device to use a device driver named driver.  If the device is already attached to a device driver and the -f flag is speci-
	     fied, the device will be detached from its current device driver before it is attached to the new device driver.  If the device is
	     already attached to a device driver and the -f flag is not specified, the device will not be changed.

SEE ALSO

     devctl(3), devinfo(8)

HISTORY

     The devctl utility first appeared in FreeBSD 11.0.

BSD
								 February 5, 2015							       BSD
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