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Thomas Maier32694852006-12-08 02:36:12 -08001What: /sys/class/pktcdvd/
2Date: Oct. 2006
Thomas Maier83f3aa32007-02-10 01:45:11 -08003KernelVersion: 2.6.20
Thomas Maier32694852006-12-08 02:36:12 -08004Contact: Thomas Maier <balagi@justmail.de>
5Description:
6
7sysfs interface
8---------------
9
10The pktcdvd module (packet writing driver) creates
11these files in the sysfs:
12(<devid> is in format major:minor )
13
14/sys/class/pktcdvd/
15 add (0200) Write a block device id (major:minor)
16 to create a new pktcdvd device and map
17 it to the block device.
18
19 remove (0200) Write the pktcdvd device id (major:minor)
20 to it to remove the pktcdvd device.
21
22 device_map (0444) Shows the device mapping in format:
23 pktcdvd[0-7] <pktdevid> <blkdevid>
24
25/sys/class/pktcdvd/pktcdvd[0-7]/
26 dev (0444) Device id
27 uevent (0200) To send an uevent.
28
29/sys/class/pktcdvd/pktcdvd[0-7]/stat/
30 packets_started (0444) Number of started packets.
31 packets_finished (0444) Number of finished packets.
32
33 kb_written (0444) kBytes written.
34 kb_read (0444) kBytes read.
35 kb_read_gather (0444) kBytes read to fill write packets.
36
37 reset (0200) Write any value to it to reset
38 pktcdvd device statistic values, like
39 bytes read/written.
40
41/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/
42 size (0444) Contains the size of the bio write
43 queue.
44
45 congestion_off (0644) If bio write queue size is below
46 this mark, accept new bio requests
47 from the block layer.
48
49 congestion_on (0644) If bio write queue size is higher
50 as this mark, do no longer accept
51 bio write requests from the block
52 layer and wait till the pktcdvd
53 device has processed enough bio's
54 so that bio write queue size is
55 below congestion off mark.
56 A value of <= 0 disables congestion
57 control.
58
59
60Example:
61--------
62To use the pktcdvd sysfs interface directly, you can do:
63
64# create a new pktcdvd device mapped to /dev/hdc
65echo "22:0" >/sys/class/pktcdvd/add
66cat /sys/class/pktcdvd/device_map
67# assuming device pktcdvd0 was created, look at stat's
68cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
69# print the device id of the mapped block device
70fgrep pktcdvd0 /sys/class/pktcdvd/device_map
71# remove device, using pktcdvd0 device id 253:0
72echo "253:0" >/sys/class/pktcdvd/remove