Documentation/s390/CommonIO

   1 S/390 common I/O-Layer - command line parameters, procfs and debugfs entries
   2 ============================================================================
   3
   4 Command line parameters
   5 -----------------------
   6
   7 * cio_msg = yes | no
   8
   9   Determines whether information on found devices and sensed device
  10   characteristics should be shown during startup or when new devices are
  11   found, i. e. messages of the types "Detected device 0.0.4711 on subchannel
  12   0.0.0042" and "SenseID: Device 0.0.4711 reports: ...".
  13
  14   Default is off.
  15
  16
  17 * cio_ignore = {all} |
  18                {<device> | <range of devices>} |
  19                {!<device> | !<range of devices>}
  20
  21   The given devices will be ignored by the common I/O-layer; no detection
  22   and device sensing will be done on any of those devices. The subchannel to
  23   which the device in question is attached will be treated as if no device was
  24   attached.
  25
  26   An ignored device can be un-ignored later; see the "/proc entries"-section for
  27   details.
  28
  29   The devices must be given either as bus ids (0.x.abcd) or as hexadecimal
  30   device numbers (0xabcd or abcd, for 2.4 backward compatibility). If you
  31   give a device number 0xabcd, it will be interpreted as 0.0.abcd.
  32
  33   You can use the 'all' keyword to ignore all devices.
  34   The '!' operator will cause the I/O-layer to _not_ ignore a device.
  35   The command line is parsed from left to right.
  36
  37   For example,
  38         cio_ignore=0.0.0023-0.0.0042,0.0.4711
  39   will ignore all devices ranging from 0.0.0023 to 0.0.0042 and the device
  40   0.0.4711, if detected.
  41   As another example,
  42         cio_ignore=all,!0.0.4711,!0.0.fd00-0.0.fd02
  43   will ignore all devices but 0.0.4711, 0.0.fd00, 0.0.fd01, 0.0.fd02.
  44
  45   By default, no devices are ignored.
  46
  47
  48 /proc entries
  49 -------------
  50
  51 * /proc/cio_ignore
  52
  53   Lists the ranges of devices (by bus id) which are ignored by common I/O.
  54
  55   You can un-ignore certain or all devices by piping to /proc/cio_ignore.
  56   "free all" will un-ignore all ignored devices,
  57   "free <device range>, <device range>, ..." will un-ignore the specified
  58   devices.
  59
  60   For example, if devices 0.0.0023 to 0.0.0042 and 0.0.4711 are ignored,
  61   - echo free 0.0.0030-0.0.0032 > /proc/cio_ignore
  62     will un-ignore devices 0.0.0030 to 0.0.0032 and will leave devices 0.0.0023
  63     to 0.0.002f, 0.0.0033 to 0.0.0042 and 0.0.4711 ignored;
  64   - echo free 0.0.0041 > /proc/cio_ignore will furthermore un-ignore device
  65     0.0.0041;
  66   - echo free all > /proc/cio_ignore will un-ignore all remaining ignored
  67     devices.
  68
  69   When a device is un-ignored, device recognition and sensing is performed and
  70   the device driver will be notified if possible, so the device will become
  71   available to the system. Note that un-ignoring is performed asynchronously.
  72
  73   You can also add ranges of devices to be ignored by piping to
  74   /proc/cio_ignore; "add <device range>, <device range>, ..." will ignore the
  75   specified devices.
  76
  77   Note: While already known devices can be added to the list of devices to be
  78         ignored, there will be no effect on then. However, if such a device
  79         disappears and then reappears, it will then be ignored.
  80
  81   For example,
  82         "echo add 0.0.a000-0.0.accc, 0.0.af00-0.0.afff > /proc/cio_ignore"
  83   will add 0.0.a000-0.0.accc and 0.0.af00-0.0.afff to the list of ignored
  84   devices.
  85
  86   The devices can be specified either by bus id (0.x.abcd) or, for 2.4 backward
  87   compatibility, by the device number in hexadecimal (0xabcd or abcd). Device
  88   numbers given as 0xabcd will be interpreted as 0.0.abcd.
  89
  90 * For some of the information present in the /proc filesystem in 2.4 (namely,
  91   /proc/subchannels and /proc/chpids), see driver-model.txt.
  92   Information formerly in /proc/irq_count is now in /proc/interrupts.
  93
  94
  95 debugfs entries
  96 ---------------
  97
  98 * /sys/kernel/debug/s390dbf/cio_*/ (S/390 debug feature)
  99
 100   Some views generated by the debug feature to hold various debug outputs.
 101
 102   - /sys/kernel/debug/s390dbf/cio_crw/sprintf
 103     Messages from the processing of pending channel report words (machine check
 104     handling).
 105
 106   - /sys/kernel/debug/s390dbf/cio_msg/sprintf
 107     Various debug messages from the common I/O-layer, including messages
 108     printed when cio_msg=yes.
 109
 110   - /sys/kernel/debug/s390dbf/cio_trace/hex_ascii
 111     Logs the calling of functions in the common I/O-layer and, if applicable,
 112     which subchannel they were called for, as well as dumps of some data
 113     structures (like irb in an error case).
 114
 115   The level of logging can be changed to be more or less verbose by piping to
 116   /sys/kernel/debug/s390dbf/cio_*/level a number between 0 and 6; see the
 117   documentation on the S/390 debug feature (Documentation/s390/s390dbf.txt)
 118   for details.