Documentation/ABI/testing/sysfs-class-pktcdvd

   1 sysfs interface
   2 ---------------
   3 The pktcdvd module (packet writing driver) creates the following files in the
   4 sysfs: (<devid> is in the format major:minor)
   5
   6 What:           /sys/class/pktcdvd/add
   7 What:           /sys/class/pktcdvd/remove
   8 What:           /sys/class/pktcdvd/device_map
   9 Date:           Oct. 2006
  10 KernelVersion:  2.6.20
  11 Contact:        Thomas Maier <balagi@justmail.de>
  12 Description:
  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
  27 What:           /sys/class/pktcdvd/pktcdvd[0-7]/dev
  28 What:           /sys/class/pktcdvd/pktcdvd[0-7]/uevent
  29 Date:           Oct. 2006
  30 KernelVersion:  2.6.20
  31 Contact:        Thomas Maier <balagi@justmail.de>
  32 Description:
  33                 dev:    (RO) Device id
  34
  35                 uevent: (WO) To send a uevent
  36
  37
  38 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_started
  39 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_finished
  40 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_written
  41 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read
  42 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read_gather
  43 What:           /sys/class/pktcdvd/pktcdvd[0-7]/stat/reset
  44 Date:           Oct. 2006
  45 KernelVersion:  2.6.20
  46 Contact:        Thomas Maier <balagi@justmail.de>
  47 Description:
  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
  63 What:           /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/size
  64 What:           /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_off
  65 What:           /sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_on
  66 Date:           Oct. 2006
  67 KernelVersion:  2.6.20
  68 Contact:        Thomas Maier <balagi@justmail.de>
  69 Description:
  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
  85 Example:
  86 --------
  87 To 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