| 1 | S/390 common I/O-Layer - command line parameters, procfs and debugfs entries |
| 2 | ============================================================================ |
| 3 | |
| 4 | Command line parameters |
| 5 | ----------------------- |
| 6 | |
| 7 | * ccw_timeout_log |
| 8 | |
| 9 | Enable logging of debug information in case of ccw device timeouts. |
| 10 | |
| 11 | * cio_ignore = {all} | |
| 12 | {<device> | <range of devices>} | |
| 13 | {!<device> | !<range of devices>} |
| 14 | |
| 15 | The given devices will be ignored by the common I/O-layer; no detection |
| 16 | and device sensing will be done on any of those devices. The subchannel to |
| 17 | which the device in question is attached will be treated as if no device was |
| 18 | attached. |
| 19 | |
| 20 | An ignored device can be un-ignored later; see the "/proc entries"-section for |
| 21 | details. |
| 22 | |
| 23 | The devices must be given either as bus ids (0.x.abcd) or as hexadecimal |
| 24 | device numbers (0xabcd or abcd, for 2.4 backward compatibility). If you |
| 25 | give a device number 0xabcd, it will be interpreted as 0.0.abcd. |
| 26 | |
| 27 | You can use the 'all' keyword to ignore all devices. |
| 28 | The '!' operator will cause the I/O-layer to _not_ ignore a device. |
| 29 | The command line is parsed from left to right. |
| 30 | |
| 31 | For example, |
| 32 | cio_ignore=0.0.0023-0.0.0042,0.0.4711 |
| 33 | will ignore all devices ranging from 0.0.0023 to 0.0.0042 and the device |
| 34 | 0.0.4711, if detected. |
| 35 | As another example, |
| 36 | cio_ignore=all,!0.0.4711,!0.0.fd00-0.0.fd02 |
| 37 | will ignore all devices but 0.0.4711, 0.0.fd00, 0.0.fd01, 0.0.fd02. |
| 38 | |
| 39 | By default, no devices are ignored. |
| 40 | |
| 41 | |
| 42 | /proc entries |
| 43 | ------------- |
| 44 | |
| 45 | * /proc/cio_ignore |
| 46 | |
| 47 | Lists the ranges of devices (by bus id) which are ignored by common I/O. |
| 48 | |
| 49 | You can un-ignore certain or all devices by piping to /proc/cio_ignore. |
| 50 | "free all" will un-ignore all ignored devices, |
| 51 | "free <device range>, <device range>, ..." will un-ignore the specified |
| 52 | devices. |
| 53 | |
| 54 | For example, if devices 0.0.0023 to 0.0.0042 and 0.0.4711 are ignored, |
| 55 | - echo free 0.0.0030-0.0.0032 > /proc/cio_ignore |
| 56 | will un-ignore devices 0.0.0030 to 0.0.0032 and will leave devices 0.0.0023 |
| 57 | to 0.0.002f, 0.0.0033 to 0.0.0042 and 0.0.4711 ignored; |
| 58 | - echo free 0.0.0041 > /proc/cio_ignore will furthermore un-ignore device |
| 59 | 0.0.0041; |
| 60 | - echo free all > /proc/cio_ignore will un-ignore all remaining ignored |
| 61 | devices. |
| 62 | |
| 63 | When a device is un-ignored, device recognition and sensing is performed and |
| 64 | the device driver will be notified if possible, so the device will become |
| 65 | available to the system. Note that un-ignoring is performed asynchronously. |
| 66 | |
| 67 | You can also add ranges of devices to be ignored by piping to |
| 68 | /proc/cio_ignore; "add <device range>, <device range>, ..." will ignore the |
| 69 | specified devices. |
| 70 | |
| 71 | Note: While already known devices can be added to the list of devices to be |
| 72 | ignored, there will be no effect on then. However, if such a device |
| 73 | disappears and then reappears, it will then be ignored. To make |
| 74 | known devices go away, you need the "purge" command (see below). |
| 75 | |
| 76 | For example, |
| 77 | "echo add 0.0.a000-0.0.accc, 0.0.af00-0.0.afff > /proc/cio_ignore" |
| 78 | will add 0.0.a000-0.0.accc and 0.0.af00-0.0.afff to the list of ignored |
| 79 | devices. |
| 80 | |
| 81 | You can remove already known but now ignored devices via |
| 82 | "echo purge > /proc/cio_ignore" |
| 83 | All devices ignored but still registered and not online (= not in use) |
| 84 | will be deregistered and thus removed from the system. |
| 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 | * /proc/cio_settle |
| 91 | |
| 92 | A write request to this file is blocked until all queued cio actions are |
| 93 | handled. This will allow userspace to wait for pending work affecting |
| 94 | device availability after changing cio_ignore or the hardware configuration. |
| 95 | |
| 96 | * For some of the information present in the /proc filesystem in 2.4 (namely, |
| 97 | /proc/subchannels and /proc/chpids), see driver-model.txt. |
| 98 | Information formerly in /proc/irq_count is now in /proc/interrupts. |
| 99 | |
| 100 | |
| 101 | debugfs entries |
| 102 | --------------- |
| 103 | |
| 104 | * /sys/kernel/debug/s390dbf/cio_*/ (S/390 debug feature) |
| 105 | |
| 106 | Some views generated by the debug feature to hold various debug outputs. |
| 107 | |
| 108 | - /sys/kernel/debug/s390dbf/cio_crw/sprintf |
| 109 | Messages from the processing of pending channel report words (machine check |
| 110 | handling). |
| 111 | |
| 112 | - /sys/kernel/debug/s390dbf/cio_msg/sprintf |
| 113 | Various debug messages from the common I/O-layer. |
| 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. |