1S/390 common I/O-Layer - command line parameters and /proc 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, i. e. messages of the types 
11  "Detected device 4711 on subchannel 42" and "SenseID: Device 4711 reports: ...".
12
13  Default is off.
14
15
16* cio_notoper_msg = yes | no
17
18  Determines whether messages of the type "Device 4711 became 'not operational'"
19  should be shown during startup; after startup, they will always be shown.
20  
21  Default is on.
22
23
24* cio_ignore = <range of device numbers>, <range of device numbers>, ...
25
26  The given device numbers 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 device numbers must be given hexadecimal.
35
36  For example, 
37	cio_ignore=0x23-0x42,0x4711
38  will ignore all devices with device numbers ranging from 23 to 42 and the 
39  device with device number 4711, if detected.
40
41  By default, no devices are ignored.
42
43
44* cio_proc_devinfo = yes | no
45
46  Determines whether the entries under /proc/deviceinfo/ (see below) should be
47  created. Since there are problems with systems with many devices attached, I
48  made it configurable.
49
50  Until the problems are dealt with, default is off.
51
52
53/proc entries
54-------------
55
56* /proc/subchannels
57
58  Shows for each subchannel
59  - device number
60  - device type/model and if applicable control unit type/model
61  - whether the device is in use
62  - path installed mask, path available mask, path operational mask and last 
63    path used mask
64  - the channel path IDs (chpids)
65
66
67* /proc/deviceinfo/
68
69  Shows in subdirectories for each device some characteristics:
70  - /proc/deviceinfo/<devno>/chpids: 
71	the channel path IDs
72  - /proc/deviceinfo/<devno>/in_use: 
73	whether the device is in use
74  - /proc/deviceinfo/<devno>/sensedata:
75    	the device type/model and if applicable control unit type/model of the
76	device
77
78  NOTE: Since the number of inodes which can be dynamically allocated by procfs
79        is limited, device entries will only be created up to a magic number of
80        devices. The kernel will utter a warning that not all entries can be
81        created. In this case, you shouldn't use "cio_proc_devinfo=yes" (see
82        above).
83
84* /proc/cio_ignore
85
86  Lists the ranges of device numbers which are ignored by common I/O.
87
88  You can un-ignore certain or all devices by piping to /proc/cio_ignore. 
89  "free all" will un-ignore all ignored devices, 
90  "free <devnorange>, <devnorange>, ..." will un-ignore the specified devices.
91
92  For example, if devices 23 to 42 and 4711 are ignored,
93  - echo free 0x30-0x32 > /proc/cio_ignore
94    will un-ignore devices 30 to 32 and will leave devices 23 to 2F, 33 to 42
95    and 4711 ignored;
96  - echo free 0x41 > /proc/cio_ignore will furthermore un-ignore device 41;
97  - echo free all > /proc/cio_ignore will un-ignore all remaining ignored 
98    devices.
99
100  When a device is un-ignored, device recognition and sensing is performed and 
101  the device driver will be notified if possible, so the device will become
102  available to the system.
103
104  You can also add ranges of devices to be ignored by piping to 
105  /proc/cio_ignore; "add <devnorange>, <devnorange>, ..." will ignore the 
106  specified devices.
107
108  Note: Already known devices cannot be ignored; this also applies to devices
109        which are gone after a machine check.
110
111  For example, if device abcd is already known and all other devices a000-afff 
112  are not known, "echo add 0xa000-0xaccc, 0xaf00-0xafff > /proc/cio_ignore" 
113  will add af00-afff to the list of ignored devices and skip a000-accc.
114
115
116* /proc/s390dbf/cio_*/ (S/390 debug feature)
117
118  Some views generated by the debug feature to hold various debug outputs.
119
120  - /proc/s390dbf/cio_crw/sprintf
121    Messages from the processing of pending channel report words (machine check
122    handling), which will also show when CONFIG_DEBUG_CRW is defined.
123
124  - /proc/s390dbf/cio_msg/sprintf
125    Various debug messages from the common I/O-layer; generally, messages which 
126    will also show when CONFIG_DEBUG_IO is defined.
127
128  - /proc/s390dbf/cio_trace/hex_ascii
129    Logs the calling of functions in the common I/O-layer and, if applicable, 
130    which subchannel they were called for.
131
132  The level of logging can be changed to be more or less verbose by piping to 
133  /proc/s390dbf/cio_*/level a number between 0 and 6; see the documentation on
134  the S/390 debug feature (Documentation/s390/s390dbf.txt) for details.
135
136* /proc/irq_count
137
138  This entry counts how many times s390_process_IRQ has been called for each 
139  CPU. This info is in /proc/interrupts on other architectures.
140