141 lines
5.0 KiB
ReStructuredText
141 lines
5.0 KiB
ReStructuredText
======================
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S/390 common I/O-Layer
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======================
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command line parameters, procfs and debugfs entries
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===================================================
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Command line parameters
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-----------------------
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* ccw_timeout_log
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Enable logging of debug information in case of ccw device timeouts.
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* cio_ignore = device[,device[,..]]
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device := {all | [!]ipldev | [!]condev | [!]<devno> | [!]<devno>-<devno>}
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The given devices will be ignored by the common I/O-layer; no detection
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and device sensing will be done on any of those devices. The subchannel to
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which the device in question is attached will be treated as if no device was
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attached.
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An ignored device can be un-ignored later; see the "/proc entries"-section for
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details.
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The devices must be given either as bus ids (0.x.abcd) or as hexadecimal
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device numbers (0xabcd or abcd, for 2.4 backward compatibility). If you
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give a device number 0xabcd, it will be interpreted as 0.0.abcd.
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You can use the 'all' keyword to ignore all devices. The 'ipldev' and 'condev'
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keywords can be used to refer to the CCW based boot device and CCW console
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device respectively (these are probably useful only when combined with the '!'
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operator). The '!' operator will cause the I/O-layer to _not_ ignore a device.
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The command line
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is parsed from left to right.
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For example::
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cio_ignore=0.0.0023-0.0.0042,0.0.4711
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will ignore all devices ranging from 0.0.0023 to 0.0.0042 and the device
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0.0.4711, if detected.
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As another example::
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cio_ignore=all,!0.0.4711,!0.0.fd00-0.0.fd02
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will ignore all devices but 0.0.4711, 0.0.fd00, 0.0.fd01, 0.0.fd02.
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By default, no devices are ignored.
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/proc entries
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-------------
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* /proc/cio_ignore
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Lists the ranges of devices (by bus id) which are ignored by common I/O.
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You can un-ignore certain or all devices by piping to /proc/cio_ignore.
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"free all" will un-ignore all ignored devices,
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"free <device range>, <device range>, ..." will un-ignore the specified
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devices.
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For example, if devices 0.0.0023 to 0.0.0042 and 0.0.4711 are ignored,
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- echo free 0.0.0030-0.0.0032 > /proc/cio_ignore
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will un-ignore devices 0.0.0030 to 0.0.0032 and will leave devices 0.0.0023
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to 0.0.002f, 0.0.0033 to 0.0.0042 and 0.0.4711 ignored;
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- echo free 0.0.0041 > /proc/cio_ignore will furthermore un-ignore device
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0.0.0041;
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- echo free all > /proc/cio_ignore will un-ignore all remaining ignored
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devices.
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When a device is un-ignored, device recognition and sensing is performed and
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the device driver will be notified if possible, so the device will become
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available to the system. Note that un-ignoring is performed asynchronously.
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You can also add ranges of devices to be ignored by piping to
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/proc/cio_ignore; "add <device range>, <device range>, ..." will ignore the
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specified devices.
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Note: While already known devices can be added to the list of devices to be
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ignored, there will be no effect on then. However, if such a device
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disappears and then reappears, it will then be ignored. To make
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known devices go away, you need the "purge" command (see below).
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For example::
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"echo add 0.0.a000-0.0.accc, 0.0.af00-0.0.afff > /proc/cio_ignore"
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will add 0.0.a000-0.0.accc and 0.0.af00-0.0.afff to the list of ignored
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devices.
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You can remove already known but now ignored devices via::
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"echo purge > /proc/cio_ignore"
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All devices ignored but still registered and not online (= not in use)
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will be deregistered and thus removed from the system.
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The devices can be specified either by bus id (0.x.abcd) or, for 2.4 backward
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compatibility, by the device number in hexadecimal (0xabcd or abcd). Device
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numbers given as 0xabcd will be interpreted as 0.0.abcd.
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* /proc/cio_settle
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A write request to this file is blocked until all queued cio actions are
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handled. This will allow userspace to wait for pending work affecting
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device availability after changing cio_ignore or the hardware configuration.
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* For some of the information present in the /proc filesystem in 2.4 (namely,
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/proc/subchannels and /proc/chpids), see driver-model.txt.
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Information formerly in /proc/irq_count is now in /proc/interrupts.
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debugfs entries
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---------------
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* /sys/kernel/debug/s390dbf/cio_*/ (S/390 debug feature)
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Some views generated by the debug feature to hold various debug outputs.
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- /sys/kernel/debug/s390dbf/cio_crw/sprintf
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Messages from the processing of pending channel report words (machine check
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handling).
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- /sys/kernel/debug/s390dbf/cio_msg/sprintf
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Various debug messages from the common I/O-layer.
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- /sys/kernel/debug/s390dbf/cio_trace/hex_ascii
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Logs the calling of functions in the common I/O-layer and, if applicable,
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which subchannel they were called for, as well as dumps of some data
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structures (like irb in an error case).
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The level of logging can be changed to be more or less verbose by piping to
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/sys/kernel/debug/s390dbf/cio_*/level a number between 0 and 6; see the
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documentation on the S/390 debug feature (Documentation/s390/s390dbf.rst)
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for details.
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