1sysfs interface
2---------------
3The pktcdvd module (packet writing driver) creates the following files in the
4sysfs: (<devid> is in the format major:minor)
5
6What:		/sys/class/pktcdvd/add
7What:		/sys/class/pktcdvd/remove
8What:		/sys/class/pktcdvd/device_map
9Date:		Oct. 2006
10KernelVersion:	2.6.20
11Contact:	Thomas Maier <balagi@justmail.de>
12Description:
13
14		==========	==============================================
15		add		(WO) Write a block device id (major:minor) to
16				create a new pktcdvd device and map it to the
17				block device.
18
19		remove		(WO) Write the pktcdvd device id (major:minor)
20				to remove the pktcdvd device.
21
22		device_map	(RO) Shows the device mapping in format:
23				pktcdvd[0-7] <pktdevid> <blkdevid>
24		==========	==============================================
25
26
27What:		/sys/class/pktcdvd/pktcdvd[0-7]/dev
28What:		/sys/class/pktcdvd/pktcdvd[0-7]/uevent
29Date:		Oct. 2006
30KernelVersion:	2.6.20
31Contact:	Thomas Maier <balagi@justmail.de>
32Description:
33		dev:	(RO) Device id
34
35		uevent:	(WO) To send a uevent
36
37
38What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_started
39What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_finished
40What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_written
41What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read
42What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read_gather
43What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/reset
44Date:		Oct. 2006
45KernelVersion:	2.6.20
46Contact:	Thomas Maier <balagi@justmail.de>
47Description:
48		packets_started:	(RO) Number of started packets.
49
50		packets_finished:	(RO) Number of finished packets.
51
52		kb_written:		(RO) kBytes written.
53
54		kb_read:		(RO) kBytes read.
55
56		kb_read_gather:		(RO) kBytes read to fill write packets.
57
58		reset:			(WO) Write any value to it to reset
59					pktcdvd device statistic values, like
60					bytes read/written.
61
62
63What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/size
64What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_off
65What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_on
66Date:		Oct. 2006
67KernelVersion:	2.6.20
68Contact:	Thomas Maier <balagi@justmail.de>
69Description:
70		==============	================================================
71		size		(RO) Contains the size of the bio write queue.
72
73		congestion_off	(RW) If bio write queue size is below this mark,
74				accept new bio requests from the block layer.
75
76		congestion_on	(RW) If bio write queue size is higher as this
77				mark, do no longer accept bio write requests
78				from the block layer and wait till the pktcdvd
79				device has processed enough bio's so that bio
80				write queue size is below congestion off mark.
81				A value of <= 0 disables congestion control.
82		==============	================================================
83
84
85Example:
86--------
87To use the pktcdvd sysfs interface directly, you can do::
88
89    # create a new pktcdvd device mapped to /dev/hdc
90    echo "22:0" >/sys/class/pktcdvd/add
91    cat /sys/class/pktcdvd/device_map
92    # assuming device pktcdvd0 was created, look at stat's
93    cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
94    # print the device id of the mapped block device
95    fgrep pktcdvd0 /sys/class/pktcdvd/device_map
96    # remove device, using pktcdvd0 device id   253:0
97    echo "253:0" >/sys/class/pktcdvd/remove
98