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1S/390 common I/O-Layer - command line parameters, procfs and debugfs entries
2============================================================================
3
4Command 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
95debugfs 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.