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+sysfs interface
+---------------
+The pktcdvd module (packet writing driver) creates the following files in the
+sysfs: (<devid> is in the format major:minor)
+
+What: /sys/class/pktcdvd/add
+What: /sys/class/pktcdvd/remove
+What: /sys/class/pktcdvd/device_map
+Date: Oct. 2006
+KernelVersion: 2.6.20
+Contact: Thomas Maier <balagi@justmail.de>
+Description:
+
+ ========== ==============================================
+ add (WO) Write a block device id (major:minor) to
+ create a new pktcdvd device and map it to the
+ block device.
+
+ remove (WO) Write the pktcdvd device id (major:minor)
+ to remove the pktcdvd device.
+
+ device_map (RO) Shows the device mapping in format:
+ pktcdvd[0-7] <pktdevid> <blkdevid>
+ ========== ==============================================
+
+
+What: /sys/class/pktcdvd/pktcdvd[0-7]/dev
+What: /sys/class/pktcdvd/pktcdvd[0-7]/uevent
+Date: Oct. 2006
+KernelVersion: 2.6.20
+Contact: Thomas Maier <balagi@justmail.de>
+Description:
+ dev: (RO) Device id
+
+ uevent: (WO) To send a uevent
+
+
+What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_started
+What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_finished
+What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_written
+What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read
+What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read_gather
+What: /sys/class/pktcdvd/pktcdvd[0-7]/stat/reset
+Date: Oct. 2006
+KernelVersion: 2.6.20
+Contact: Thomas Maier <balagi@justmail.de>
+Description:
+ packets_started: (RO) Number of started packets.
+
+ packets_finished: (RO) Number of finished packets.
+
+ kb_written: (RO) kBytes written.
+
+ kb_read: (RO) kBytes read.
+
+ kb_read_gather: (RO) kBytes read to fill write packets.
+
+ reset: (WO) Write any value to it to reset
+ pktcdvd device statistic values, like
+ bytes read/written.
+
+
+What: /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/size
+What: /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_off
+What: /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_on
+Date: Oct. 2006
+KernelVersion: 2.6.20
+Contact: Thomas Maier <balagi@justmail.de>
+Description:
+ ============== ================================================
+ size (RO) Contains the size of the bio write queue.
+
+ congestion_off (RW) If bio write queue size is below this mark,
+ accept new bio requests from the block layer.
+
+ congestion_on (RW) If bio write queue size is higher as this
+ mark, do no longer accept bio write requests
+ from the block layer and wait till the pktcdvd
+ device has processed enough bio's so that bio
+ write queue size is below congestion off mark.
+ A value of <= 0 disables congestion control.
+ ============== ================================================
+
+
+Example:
+--------
+To use the pktcdvd sysfs interface directly, you can do::
+
+ # create a new pktcdvd device mapped to /dev/hdc
+ echo "22:0" >/sys/class/pktcdvd/add
+ cat /sys/class/pktcdvd/device_map
+ # assuming device pktcdvd0 was created, look at stat's
+ cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
+ # print the device id of the mapped block device
+ fgrep pktcdvd0 /sys/class/pktcdvd/device_map
+ # remove device, using pktcdvd0 device id 253:0
+ echo "253:0" >/sys/class/pktcdvd/remove