common_io.rst 5.0 KB

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