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linux
1S/390 common I/O-Layer - command line parameters, procfs and debugfs entries
2============================================================================
3
4Command line parameters
5-----------------------
6
7* ccw_timeout_log
8
9 Enable logging of debug information in case of ccw device timeouts.
10
11
12* cio_msg = yes | no
13
14 Determines whether information on found devices and sensed device
15 characteristics should be shown during startup or when new devices are
16 found, i. e. messages of the types "Detected device 0.0.4711 on subchannel
17 0.0.0042" and "SenseID: Device 0.0.4711 reports: ...".
18
19 Default is off.
20
21
22* cio_ignore = {all} |
23 {<device> | <range of devices>} |
24 {!<device> | !<range of devices>}
25
26 The given devices will be ignored by the common I/O-layer; no detection
27 and device sensing will be done on any of those devices. The subchannel to
28 which the device in question is attached will be treated as if no device was
29 attached.
30
31 An ignored device can be un-ignored later; see the "/proc entries"-section for
32 details.
33
34 The devices must be given either as bus ids (0.x.abcd) or as hexadecimal
35 device numbers (0xabcd or abcd, for 2.4 backward compatibility). If you
36 give a device number 0xabcd, it will be interpreted as 0.0.abcd.
37
38 You can use the 'all' keyword to ignore all devices.
39 The '!' operator will cause the I/O-layer to _not_ ignore a device.
40 The command line is parsed from left to right.
41
42 For example,
43 cio_ignore=0.0.0023-0.0.0042,0.0.4711
44 will ignore all devices ranging from 0.0.0023 to 0.0.0042 and the device
45 0.0.4711, if detected.
46 As another example,
47 cio_ignore=all,!0.0.4711,!0.0.fd00-0.0.fd02
48 will ignore all devices but 0.0.4711, 0.0.fd00, 0.0.fd01, 0.0.fd02.
49
50 By default, no devices are ignored.
51
52
53/proc entries
54-------------
55
56* /proc/cio_ignore
57
58 Lists the ranges of devices (by bus id) which are ignored by common I/O.
59
60 You can un-ignore certain or all devices by piping to /proc/cio_ignore.
61 "free all" will un-ignore all ignored devices,
62 "free <device range>, <device range>, ..." will un-ignore the specified
63 devices.
64
65 For example, if devices 0.0.0023 to 0.0.0042 and 0.0.4711 are ignored,
66 - echo free 0.0.0030-0.0.0032 > /proc/cio_ignore
67 will un-ignore devices 0.0.0030 to 0.0.0032 and will leave devices 0.0.0023
68 to 0.0.002f, 0.0.0033 to 0.0.0042 and 0.0.4711 ignored;
69 - echo free 0.0.0041 > /proc/cio_ignore will furthermore un-ignore device
70 0.0.0041;
71 - echo free all > /proc/cio_ignore will un-ignore all remaining ignored
72 devices.
73
74 When a device is un-ignored, device recognition and sensing is performed and
75 the device driver will be notified if possible, so the device will become
76 available to the system. Note that un-ignoring is performed asynchronously.
77
78 You can also add ranges of devices to be ignored by piping to
79 /proc/cio_ignore; "add <device range>, <device range>, ..." will ignore the
80 specified devices.
81
82 Note: While already known devices can be added to the list of devices to be
83 ignored, there will be no effect on then. However, if such a device
84 disappears and then reappears, it will then be ignored.
85
86 For example,
87 "echo add 0.0.a000-0.0.accc, 0.0.af00-0.0.afff > /proc/cio_ignore"
88 will add 0.0.a000-0.0.accc and 0.0.af00-0.0.afff to the list of ignored
89 devices.
90
91 The devices can be specified either by bus id (0.x.abcd) or, for 2.4 backward
92 compatibility, by the device number in hexadecimal (0xabcd or abcd). Device
93 numbers given as 0xabcd will be interpreted as 0.0.abcd.
94
95* For some of the information present in the /proc filesystem in 2.4 (namely,
96 /proc/subchannels and /proc/chpids), see driver-model.txt.
97 Information formerly in /proc/irq_count is now in /proc/interrupts.
98
99
100debugfs entries
101---------------
102
103* /sys/kernel/debug/s390dbf/cio_*/ (S/390 debug feature)
104
105 Some views generated by the debug feature to hold various debug outputs.
106
107 - /sys/kernel/debug/s390dbf/cio_crw/sprintf
108 Messages from the processing of pending channel report words (machine check
109 handling).
110
111 - /sys/kernel/debug/s390dbf/cio_msg/sprintf
112 Various debug messages from the common I/O-layer, including messages
113 printed when cio_msg=yes.
114
115 - /sys/kernel/debug/s390dbf/cio_trace/hex_ascii
116 Logs the calling of functions in the common I/O-layer and, if applicable,
117 which subchannel they were called for, as well as dumps of some data
118 structures (like irb in an error case).
119
120 The level of logging can be changed to be more or less verbose by piping to
121 /sys/kernel/debug/s390dbf/cio_*/level a number between 0 and 6; see the
122 documentation on the S/390 debug feature (Documentation/s390/s390dbf.txt)
123 for details.