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+What: /sys/class/pktcdvd/
+Date: Oct. 2006
+KernelVersion: 2.6.20
+Contact: Thomas Maier <balagi@justmail.de>
+Description:
+
+sysfs interface
+---------------
+
+The pktcdvd module (packet writing driver) creates
+these files in the sysfs:
+(<devid> is in format major:minor )
+
+/sys/class/pktcdvd/
+ add (0200) Write a block device id (major:minor)
+ to create a new pktcdvd device and map
+ it to the block device.
+
+ remove (0200) Write the pktcdvd device id (major:minor)
+ to it to remove the pktcdvd device.
+
+ device_map (0444) Shows the device mapping in format:
+ pktcdvd[0-7] <pktdevid> <blkdevid>
+
+/sys/class/pktcdvd/pktcdvd[0-7]/
+ dev (0444) Device id
+ uevent (0200) To send an uevent.
+
+/sys/class/pktcdvd/pktcdvd[0-7]/stat/
+ packets_started (0444) Number of started packets.
+ packets_finished (0444) Number of finished packets.
+
+ kb_written (0444) kBytes written.
+ kb_read (0444) kBytes read.
+ kb_read_gather (0444) kBytes read to fill write packets.
+
+ reset (0200) Write any value to it to reset
+ pktcdvd device statistic values, like
+ bytes read/written.
+
+/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/
+ size (0444) Contains the size of the bio write
+ queue.
+
+ congestion_off (0644) If bio write queue size is below
+ this mark, accept new bio requests
+ from the block layer.
+
+ congestion_on (0644) 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