Documentation/arch/s390/common_io.rst

Source file repositories/reference/linux-study-clean/Documentation/arch/s390/common_io.rst

File Facts

System
Linux kernel
Corpus path
Documentation/arch/s390/common_io.rst
Extension
.rst
Size
5124 bytes
Lines
141
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

======================
S/390 common I/O-Layer
======================

command line parameters, procfs and debugfs entries
===================================================

Command line parameters
-----------------------

* ccw_timeout_log

  Enable logging of debug information in case of ccw device timeouts.

* cio_ignore = device[,device[,..]]

	device := {all | [!]ipldev | [!]condev | [!]<devno> | [!]<devno>-<devno>}

  The given devices will be ignored by the common I/O-layer; no detection
  and device sensing will be done on any of those devices. The subchannel to
  which the device in question is attached will be treated as if no device was
  attached.

  An ignored device can be un-ignored later; see the "/proc entries"-section for
  details.

  The devices must be given either as bus ids (0.x.abcd) or as hexadecimal
  device numbers (0xabcd or abcd, for 2.4 backward compatibility). If you
  give a device number 0xabcd, it will be interpreted as 0.0.abcd.

  You can use the 'all' keyword to ignore all devices. The 'ipldev' and 'condev'
  keywords can be used to refer to the CCW based boot device and CCW console
  device respectively (these are probably useful only when combined with the '!'
  operator). The '!' operator will cause the I/O-layer to _not_ ignore a device.
  The command line
  is parsed from left to right.

  For example::

	cio_ignore=0.0.0023-0.0.0042,0.0.4711

  will ignore all devices ranging from 0.0.0023 to 0.0.0042 and the device
  0.0.4711, if detected.

  As another example::

	cio_ignore=all,!0.0.4711,!0.0.fd00-0.0.fd02

  will ignore all devices but 0.0.4711, 0.0.fd00, 0.0.fd01, 0.0.fd02.

  By default, no devices are ignored.


/proc entries
-------------

* /proc/cio_ignore

  Lists the ranges of devices (by bus id) which are ignored by common I/O.

  You can un-ignore certain or all devices by piping to /proc/cio_ignore.
  "free all" will un-ignore all ignored devices,
  "free <device range>, <device range>, ..." will un-ignore the specified
  devices.

  For example, if devices 0.0.0023 to 0.0.0042 and 0.0.4711 are ignored,

  - echo free 0.0.0030-0.0.0032 > /proc/cio_ignore
    will un-ignore devices 0.0.0030 to 0.0.0032 and will leave devices 0.0.0023
    to 0.0.002f, 0.0.0033 to 0.0.0042 and 0.0.4711 ignored;

Annotation

Implementation Notes