cio_ignore - List devices to be ignored

Ubuntu 22.04 LTS 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 IBM® Z boots, it senses and analyzes all available I/O devices. You can use the cio_ignore= kernel parameter to list specifications for devices that are to be ignored. This exclusion list can cover all possible devices, even devices that do not actually exist. 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

<device_spec>

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 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
```