Configuring the Linux console on IBM Power Systems servers

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IBM® Power Systems™ or PowerLinux servers that have been preloaded with Red Hat Enterprise Linux or SUSE Linux Enterprise Server are configured by default to use the Hardware Management Console (HMC). However, you can configure a different type of console, such as a VGA or serial console.

If you are using SUSE Linux Enterprise Server, you need only connect the console you want to use. The console will be recognized by the system using the default setup. However, if you are using Red Hat Enterprise Linux, additional steps are required to configure the console so that it will be recognized by the system.

This document describes the procedure to connect and configure the Linux console for output to VGA and serial ports. These instructions can be performed by anyone with physical access to the Power Systems server.

 

Contents

 

Required equipment

The following table lists the equipment required for each console configuration.

Console Equipment
Equipment required for VGA and serial consoles
VGA DVI cable, or dual-DVI cable (small form factor models only)
Serial

RJ-45 to RS-232 serial adapter

RS-232 serial cable with null modem

 

 

 

 

 

 

 

 

IBM pre-configured boot targets

IBM Power Systems servers that have been preloaded with Red Hat Enterprise Linux or SUSE Linux Enterprise Server might have one or more of the following boot targets already configured:

  • linux

  • linux-vga

  • linux-serial

To display the list of pre-configured boot targets, press the Tab key at the yaboot boot: prompt.

 

Using the linux target

The default boot target is linux. The console is configured to output to the HMC console device, hvc0. Use this option if your system is connected to an HMC, and you want to use the HMC as the console. To use this boot target, complete the following steps:

  1. Set up the HMC. Refer to Setting up the HMC in the Systems Hardware Information Center for instructions.

  2. Power on the system. If the system is already powered on and the console is blank, reboot the system by pressing Ctrl+Alt+Delete. The system will boot and you will be presented with the yaboot boot: prompt.

  3. At the boot: prompt, type linux and press Enter. The system will continue the boot process.

  4. View the HMC console and verify that kernel messages are being displayed.

 

Using the linux-vga target

This target is similar to the linux target, but the console is configured to output to the master TTY device tty0. Use this target if your system is not connected to an HMC, but you want to have the console on a VGA port.



To use this boot target, complete the following steps:

  1. Connect the VGA monitor to one of the available DVI ports with the provided DVI cable.

  2. Power on the system. If the system is already powered on and the console is blank, reboot the system by pressing Ctrl+Alt+Delete. The system will boot and you will be presented with the yaboot boot: prompt. If you are using SUSE Linux Enterprise Server, you do not need to complete the additional steps. Proceed to the next step if you are using Red Hat Enterprise Linux.

  3. At the boot: prompt, type linux-vga and press Enter. The system will continue the boot process.

  4. View the VGA console and verify that kernel messages are being displayed.

  5. Edit /etc/yaboot.conf and add default=linux-vga to make linux-vga the default boot target. For example, /etc/yaboot.conf should contain:

...

enablenetboot

nonvram

fstype=raw

default=linux-vga

image=...

 

Using the linux-serial target

This target is similar to the linux target, but the console is configured to output to the first serial device hvsi0. Use this target if your system is not connected to an HMC and you want to have the console on a real serial port.



To use this boot target, complete the following steps:

  1. Connect the RJ-45 connector of the serial adapter to the first RJ-45 serial port (labeled P1-T1) on the rear panel.

  2. Using a serial cable that is equipped with a null modem, connect the RS-232 connector of the serial adapter to the RS-232 serial port of the console.

  3. The default baud rate, parity, and word length (bits) should be set to "19200n8". See Configuring a system port for call options in the Systems Hardware Information Center for instructions for displaying and changing these values.

  4. Power on the system. If the system is already powered on and the console is blank, reboot the system by pressing Ctrl+Alt+Delete. The system will boot and you will be presented with the yaboot boot: prompt. If you are using SUSE Linux Enterprise Server, you do not need to complete the additional steps. Proceed to the next step if you are using Red Hat Enterprise Linux.

  5. At the boot: prompt, type linux-serial and press Enter. The system will continue the boot process.

  6. View the serial console and verify that kernel messages are being displayed.

  7. Edit /etc/yaboot.conf and add default=linux-serial to make linux-serial the default boot target. For example, /etc/yaboot.conf should contain:

...

enablenetboot

nonvram

fstype=raw

default=linux-serial

image=...

 

Manually configuring a console device

Additional console devices can be configured by adding the console parameter to the kernel command line on the yaboot boot: prompt. Any console device specified in this way will be configured in addition to the console selected in the boot target.



Note: Only a single device of a given console type (for example, VGA, serial, etc.) can be configured at one time.

 

Configuring a VGA console

 

To configure a VGA console, complete the following steps:

  1. Connect the VGA monitor to one of the available DVI ports with the provided DVI cable.

  2. Power on the system. If the system is already powered on and the console is blank, reboot the system by pressing Ctrl+Alt+Delete. The system will boot and you will be presented with the yaboot boot: prompt. If you are using SUSE Linux Enterprise Server, you do not need to complete the additional steps. Proceed to the next step if you are using Red Hat Enterprise Linux.

  3. For VGA consoles, the console parameter takes the following form:

    console=ttyX

    X is the device number (0, 1, 2, etc.). Choosing X=0 selects the foreground virtual console.

    Type the following command at the boot: prompt and press Enter:

    linux console=tty0

    The system will continue the boot process, and kernel messages should appear on the VGA console.

  4. View the VGA console and verify that kernel messages are being displayed.

  5. Edit /etc/yaboot.conf and replace console=hvc0 with console=tty0 in the append line of the default boot target. For example, /etc/yaboot.conf should contain:

append="rd_NO_LUKS LANG=en_US.UTF-9 rd_NO_MD console=tty0 KEYTABLE=us...





Configuring a serial console

 

To configure a serial console, complete the following steps:

  1. Connect the RJ-45 connector of the serial adapter to the first RJ-45 serial port (labeled P1-T1) on the rear panel.

  2. Using a serial cable that is equipped with a null modem, connect the RS-232 connector of the serial adapter to the RS-232 serial port of the console.

  3. The default baud rate, parity, and word length (bits) should be set to "19200n8". See Configuring a system port for call options in the Systems Hardware Information Center for instructions for displaying and changing these values.

  4. Power on the system. If the system is already powered on and the console is blank, reboot the system by pressing Ctrl+Alt+Delete. The system will boot and you will be presented with the yabootboot: prompt. If you are using SUSE Linux Enterprise Server, you do not need to complete the additional steps. Proceed to the next step if you are using Red Hat Enterprise Linux.

  5. For serial consoles, the console parameter takes the following form:

    console=hvsiX

    X is the port number (0, 1, 2, etc.). Choosing X=0 selects the first serial port.

    Enter the following command at the boot: prompt and press Enter:

    linux console=hvsi0

  6. View the serial console and verify that kernel messages are being displayed.

  7. Edit /etc/yaboot.conf and replace console=hvc0 with console=hvsi0 in the append line of the default boot target. For example, /etc/yaboot.conf should contain:

append="rd_NO_LUKS LANG=en_US.UTF-9 rd_NO_MD console=hvsi0 KEYTABLE=us...

 





Troubleshooting

The following table lists possible problems, causes, and corrective actions







 

Problem Cause Corrective actions
Troubleshooting information

The VGA console is blank when using the dual-DVI cable.

Sometimes only a single DVI connector of the cable is active.

1. Remove the current DVI connector from the monitor.

2. Connect the other DVI connector to the monitor.