cio_ignore - List devices to be ignored

Red Hat Enterprise Linux 8.4 LPAR mode z/VM guest KVM guest

Use the cio_ignore= kernel parameter to list specifications for I/O devices that are to be ignored.

When an instance of Linux on Z boots, it senses and analyzes all available I/O devices. The following applies to ignored devices:
  • Ignored devices are not sensed and analyzed. The device cannot be used until it is analyzed.
  • Ignored devices are not represented in sysfs.
  • Ignored devices do not occupy storage in the kernel.
  • The subchannel to which an ignored device is attached is treated as if no device were attached.
  • For Linux on z/VM®, cio_ignore might hide essential devices such as the console. The console is typically device number 0.0.0009.

Format

cio_ignore syntax

Read syntax diagramSkip visual syntax diagramcio_ignore=all<device_spec>,,!<device_spec>
<device_spec>
Read syntax diagramSkip visual syntax diagram<device_bus_id><from_device_bus_id>-<to_device_bus_id>ipldevcondev
Where:
all
states that all devices are to be ignored.
<device_bus_id>
specifies a device. Device bus-IDs are of the form 0.<n>.<devno>, where <n> is a subchannel set ID and <devno> is a device number.
<from_device_bus_id>-<to_device_bus_id>
are two device bus-IDs that specify the first and the last device in a range of devices.
ipldev
specifies the IPL device. Use this keyword with the ! operator to avoid ignoring the IPL device.
condev
specifies the CCW console. Use this keyword with the ! operator to avoid ignoring the console device.
!
makes the following term an exclusion statement. This operator is used to exclude individual devices or ranges of devices from a preceding more general specification of devices.

Examples

  • This example specifies that all devices in the range 0.0.b100 through 0.0.b1ff, and the device 0.0.a100 are to be ignored.
    cio_ignore=0.0.b100-0.0.b1ff,0.0.a100
  • This example specifies that all devices are to be ignored.
    cio_ignore=all
  • This example specifies that all devices except the console are to be ignored.
    cio_ignore=all,!condev
  • This example specifies that all devices but the range 0.0.b100 through 0.0.b1ff, and the device 0.0.a100 are to be ignored.
     cio_ignore=all,!0.0.b100-0.0.b1ff,!0.0.a100
  • This example specifies that all devices in the range 0.0.1000 through 0.0.1500 are to be ignored, except for devices in the range 0.0.1100 through 0.0.1120.
    cio_ignore=0.0.1000-0.0.1500,!0.0.1100-0.0.1120

    This is equivalent to the following specification:

    cio_ignore=0.0.1000-0.0.10ff,0.0.1121-0.0.1500
  • This example specifies that all devices in range 0.0.1000 through 0.0.1100 and all devices in range 0.1.7000 through 0.1.7010, plus device 0.0.1234 and device 0.1.4321 are to be ignored.
    cio_ignore=0.0.1000-0.0.1100, 0.1.7000-0.1.7010, 0.0.1234, 0.1.4321