Setting a CCW terminal device online or offline

Red Hat Enterprise Linux 8.6 z/VM guest

The 3270 terminal device driver uses CCW devices and provides them as CCW terminal devices.

About this task

This section applies to Linux® on z/VM®. A CCW terminal device can be:
  • The tty3270 terminal device that can be activated for receiving Linux kernel messages.

    If this device exists, it comes online early during the Linux boot process. In a default z/VM environment, the device number for this device is 0009. In sysfs, it is represented as /sys/bus/ccw/drivers/3270/0.0.0009. You need not set this device online and you must not set it offline.

  • CCW terminal devices through which users can log in to Linux with the CP DIAL command.

    These devices are defined with the CP DEF GRAF command. They are represented in sysfs as /sys/bus/ccw/drivers/3270/0.<n>.<devno> where <n> is the subchannel set ID and <devno> is the virtual device number. By setting these devices online, you enable them for user logins. If you set a device offline, it can no longer be used for user login.

See z/VM: CP Commands and Utilities Reference, SC24-6268 for more information about the DEF GRAF and DIAL commands.

Procedure

You can use the chccwdev command to set a CCW terminal device online or offline. Alternatively, you can write 1 to the device's online attribute to set it online, or 0 to set it offline.

Examples

  • To set a CCW terminal device 0.0.7b01 online, issue: 
    # chccwdev -e 0.0.7b01
    Alternatively issue: 
    # echo 1 > /sys/bus/ccw/drivers/3270/0.0.7b01/online
  • To set a CCW terminal device 0.0.7b01 offline, issue: 
    # chccwdev -d 0.0.7b01
    Alternatively issue: 
    # echo 0 > /sys/bus/ccw/drivers/3270/0.0.7b01/online