LXR linux/Documentation/s390/common

   1======================
   2S/390 common I/O-Layer
   3======================
   4
   5command line parameters, procfs and debugfs entries
   6===================================================
   7
   8Command line parameters
   9-----------------------
  10
  11* ccw_timeout_log
  12
  13  Enable logging of debug information in case of ccw device timeouts.
  14
  15* cio_ignore = device[,device[,..]]
  16
  17        device := {all | [!]ipldev | [!]condev | [!]<devno> | [!]<devno>-<devno>}
  18
  19  The given devices will be ignored by the common I/O-layer; no detection
  20  and device sensing will be done on any of those devices. The subchannel to
  21  which the device in question is attached will be treated as if no device was
  22  attached.
  23
  24  An ignored device can be un-ignored later; see the "/proc entries"-section for
  25  details.
  26
  27  The devices must be given either as bus ids (0.x.abcd) or as hexadecimal
  28  device numbers (0xabcd or abcd, for 2.4 backward compatibility). If you
  29  give a device number 0xabcd, it will be interpreted as 0.0.abcd.
  30
  31  You can use the 'all' keyword to ignore all devices. The 'ipldev' and 'condev'
  32  keywords can be used to refer to the CCW based boot device and CCW console
  33  device respectively (these are probably useful only when combined with the '!'
  34  operator). The '!' operator will cause the I/O-layer to _not_ ignore a device.
  35  The command line
  36  is parsed from left to right.
  37
  38  For example::
  39
  40        cio_ignore=0.0.0023-0.0.0042,0.0.4711
  41
  42  will ignore all devices ranging from 0.0.0023 to 0.0.0042 and the device
  43  0.0.4711, if detected.
  44
  45  As another example::
  46
  47        cio_ignore=all,!0.0.4711,!0.0.fd00-0.0.fd02
  48
  49  will ignore all devices but 0.0.4711, 0.0.fd00, 0.0.fd01, 0.0.fd02.
  50
  51  By default, no devices are ignored.
  52
  53
  54/proc entries
  55-------------
  56
  57* /proc/cio_ignore
  58
  59  Lists the ranges of devices (by bus id) which are ignored by common I/O.
  60
  61  You can un-ignore certain or all devices by piping to /proc/cio_ignore.
  62  "free all" will un-ignore all ignored devices,
  63  "free <device range>, <device range>, ..." will un-ignore the specified
  64  devices.
  65
  66  For example, if devices 0.0.0023 to 0.0.0042 and 0.0.4711 are ignored,
  67
  68  - echo free 0.0.0030-0.0.0032 > /proc/cio_ignore
  69    will un-ignore devices 0.0.0030 to 0.0.0032 and will leave devices 0.0.0023
  70    to 0.0.002f, 0.0.0033 to 0.0.0042 and 0.0.4711 ignored;
  71  - echo free 0.0.0041 > /proc/cio_ignore will furthermore un-ignore device
  72    0.0.0041;
  73  - echo free all > /proc/cio_ignore will un-ignore all remaining ignored
  74    devices.
  75
  76  When a device is un-ignored, device recognition and sensing is performed and
  77  the device driver will be notified if possible, so the device will become
  78  available to the system. Note that un-ignoring is performed asynchronously.
  79
  80  You can also add ranges of devices to be ignored by piping to
  81  /proc/cio_ignore; "add <device range>, <device range>, ..." will ignore the
  82  specified devices.
  83
  84  Note: While already known devices can be added to the list of devices to be
  85        ignored, there will be no effect on then. However, if such a device
  86        disappears and then reappears, it will then be ignored. To make
  87        known devices go away, you need the "purge" command (see below).
  88
  89  For example::
  90
  91        "echo add 0.0.a000-0.0.accc, 0.0.af00-0.0.afff > /proc/cio_ignore"
  92
  93  will add 0.0.a000-0.0.accc and 0.0.af00-0.0.afff to the list of ignored
  94  devices.
  95
  96  You can remove already known but now ignored devices via::
  97
  98        "echo purge > /proc/cio_ignore"
  99
 100  All devices ignored but still registered and not online (= not in use)
 101  will be deregistered and thus removed from the system.
 102
 103  The devices can be specified either by bus id (0.x.abcd) or, for 2.4 backward
 104  compatibility, by the device number in hexadecimal (0xabcd or abcd). Device
 105  numbers given as 0xabcd will be interpreted as 0.0.abcd.
 106
 107* /proc/cio_settle
 108
 109  A write request to this file is blocked until all queued cio actions are
 110  handled. This will allow userspace to wait for pending work affecting
 111  device availability after changing cio_ignore or the hardware configuration.
 112
 113* For some of the information present in the /proc filesystem in 2.4 (namely,
 114  /proc/subchannels and /proc/chpids), see driver-model.txt.
 115  Information formerly in /proc/irq_count is now in /proc/interrupts.
 116
 117
 118debugfs entries
 119---------------
 120
 121* /sys/kernel/debug/s390dbf/cio_*/ (S/390 debug feature)
 122
 123  Some views generated by the debug feature to hold various debug outputs.
 124
 125  - /sys/kernel/debug/s390dbf/cio_crw/sprintf
 126    Messages from the processing of pending channel report words (machine check
 127    handling).
 128
 129  - /sys/kernel/debug/s390dbf/cio_msg/sprintf
 130    Various debug messages from the common I/O-layer.
 131
 132  - /sys/kernel/debug/s390dbf/cio_trace/hex_ascii
 133    Logs the calling of functions in the common I/O-layer and, if applicable,
 134    which subchannel they were called for, as well as dumps of some data
 135    structures (like irb in an error case).
 136
 137  The level of logging can be changed to be more or less verbose by piping to
 138  /sys/kernel/debug/s390dbf/cio_*/level a number between 0 and 6; see the
 139  documentation on the S/390 debug feature (Documentation/s390/s390dbf.rst)
 140  for details.
 141