Creating an LCS group device

Red Hat Enterprise Linux 9.2 LPAR mode z/VM guest

Use the group attribute to create an LCS group device.

Before you begin

You must know the device bus-IDs that correspond to the read and write subchannel of your OSA card. The subchannel is defined in the IOCDS of your mainframe.

Procedure

To define an LCS group device, write the device bus-IDs of the subchannel pair to /sys/bus/ccwgroup/drivers/lcs/group.

Issue a command of this form:

# echo <read_device_bus_id>,<write_device_bus_id> > /sys/bus/ccwgroup/drivers/lcs/group

Results

The lcs device driver uses the device bus-ID of the read subchannel to create a directory for a group device:

/sys/bus/ccwgroup/drivers/lcs/<read_device_bus_id>

This directory contains a number of attributes that determine the settings of the LCS group device. The following sections describe how to use these attributes to configure an LCS group device.

Example

Assuming that 0.0.d000 is the device bus-ID that corresponds to a read subchannel:

# echo 0.0.d000,0.0.d001 > /sys/bus/ccwgroup/drivers/lcs/group

This command results in the creation of the following directories in sysfs:

/sys/bus/ccwgroup/drivers/lcs/0.0.d000
/sys/bus/ccwgroup/devices/0.0.d000
/sys/devices/lcs/0.0.d000

Note: When the device subchannels are added, device types 3088/08 and 3088/1f can be assigned to either the CTCM or the LCS device driver.

To check which devices are assigned to which device driver, issue the following commands:

# ls -l /sys/bus/ccw/drivers/ctcm
# ls -l /sys/bus/ccw/drivers/lcs

To change a faulty assignment, use the unbind and bind attributes of the device. For example, to change the assignment for device bus-IDs 0.0.2000 and 0.0.2001 issue the following commands:

# echo 0.0.2000 > /sys/bus/ccw/drivers/ctcm/unbind
# echo 0.0.2000 > /sys/bus/ccw/drivers/lcs/bind
# echo 0.0.2001 > /sys/bus/ccw/drivers/ctcm/unbind
# echo 0.0.2001 > /sys/bus/ccw/drivers/lcs/bind