openshift-docs/modules/installation-user-infra-machines-advanced-enabling-serial-console.adoc

// Module included in the following assemblies:
//
// * installing/installing_bare_metal/upi/installing-bare-metal.adoc
// * installing/installing_bare_metal/upi/installing-restricted-networks-bare-metal.adoc
// * installing/installing_bare_metal/upi/installing-bare-metal-network-customizations.adoc

ifeval::["{context}" == "installing-restricted-networks-bare-metal"]
:restricted:
endif::[]

:_mod-docs-content-type: PROCEDURE
[id="installation-user-infra-machines-advanced-enabling-serial-console_{context}"]
= Enabling the serial console for PXE and ISO installations

[role="_abstract"]
By default, the {op-system-first} serial console is disabled and all output is written to the graphical console. You can enable the serial console for an ISO installation and reconfigure the bootloader so that output is sent to both the serial console and the graphical console.

.Procedure

. Boot the ISO installer.

. Run the `coreos-installer` command to install the system, adding the `--console` option once to specify the graphical console, and a second time to specify the serial console:
+
ifndef::restricted[]
[source,terminal]
----
$ coreos-installer install \
--console=tty0 \//
--console=ttyS0,<options> \//
--ignition-url=http://host/worker.ign /dev/disk/by-id/scsi-<serial_number>
----
endif::[]
ifdef::restricted[]
[source,terminal]
----
$ coreos-installer install \
--console=tty0 \//
--console=ttyS0,<options> \//
--ignition-url=http://host/worker.ign \
--offline \
/dev/disk/by-id/scsi-<serial_number>
----
endif::[]
+
where:
+
`--console=tty0`:: The desired secondary console. In this case, the graphical console. Omitting this option will disable the graphical console.
`--console=ttyS0`:: The desired primary console. In this case, the serial console. The `options` field defines the baud rate and other settings. A common value for this field is `115200n8`. If no options are provided, the default kernel value of `9600n8` is used. For more information on the format of this option, see link:https://www.kernel.org/doc/html/latest/admin-guide/serial-console.html[Linux kernel serial console] documentation.

. Reboot into the installed system.
+
[NOTE]
====
A similar outcome can be obtained by using the `coreos-installer install --append-karg` option, and specifying the console with `console=`. However, this will only set the console for the kernel and not the bootloader.
====
+
To configure a PXE installation, make sure the `coreos.inst.install_dev` kernel command-line option is omitted, and use the shell prompt to run `coreos-installer` manually using the above ISO installation procedure.

ifeval::["{context}" == "installing-restricted-networks-bare-metal"]
:!restricted:
endif::[]