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Serial Port Console Redirection

Dell™ OpenManage™ Baseboard Management Controller Utilities User's Guide

  Serial Communication

  SPCR Table

  Serial Console redirection With SOL Proxy

Serial Communication

For PowerEdge x9xx and xx0x servers, serial console redirection can be accomplished using COM1 or COM2.

Console Redirection Via COM1

To activate serial console redirection via COM1, you must configure the following settings:

Set Serial Communication-> Serial Communication to On with Console Redirection via COM1

Set Serial Communication-> External Serial Connector to COM1

Console Redirection Via COM2

Console Redirection via COM2 can be used to redirect either to the external connector or to the remote access device, such as a BMC or DRAC 5, for Serial Over LAN (SOL) communication.

To activate serial console redirection via COM2, you must configure the following settings:

Set Serial Communication-> Serial Communication to On with Console Redirection via COM2

Set Serial Communication-> External Serial Connector to COM2

NOTE: If the console redirection is used for SOL then the External Serial Connector setting does not need to be configured.

When using COM2 for console redirection regardless of whether you redirect to the external connector or for SOL, the BIOS reads the SOL baud rate from the BMC and uses that setting to activate console redirection. SOL baud rate can be configured using the Dell Deployment Toolkit, OMSA, DRAC, or the BMU.

Serial Terminal Communication to BMC or DRAC

Serial Terminal Mode allows you to directly connect to the BMC or DRAC using a serial port connection and execute text-based commands. Refer to the Appendix B for information about configuring your BMC and DRAC for Serial Terminal Communication as well as available Terminal Mode Commands.

In Terminal Mode, the BMC or the DRAC, if present, support Escape key sequences that allow switching between the Serial Terminal Connection and the connection to the system COM2 port. This can be combined with the Console Redirection via COM2 (see "Console Redirection Via COM2") to switch between viewing the system console redirection and communicating to BMC or DRAC to execute the terminal commands such as system reset.

NOTE: For this combined functionality, Serial Communication baud rate and the SOL baud rate must be set to the same value.

When in terminal mode, to switch the connection to the system COM2 port use:

<Esc> +<Shift> <q>

When connected to the system COM2 port, to go back to the terminal mode use:

<Esc> +<Shift> <9>

SPCR Table

The Serial Port Console Redirection (SPCR) table provides information about how the system firmware and service processor use the out-of-band (OOB) management port. For example, if the OOB Management port is a serial port, the SPCR table contains information such as serial port number, baud terminal type, and other settings used for OOB communication. The SPCR table is read by the Special Administrative Console (SAC) for console redirection and configures itself automatically during a bootable CD installation.

The SPCR table is automatically enabled if the system service processor supports Emergency Management Services (EMS) such as console redirection. If it is not configured automatically, you must configure SPCR to match BMC settings by adding the following parameters to the unattend.txt file.

NOTE: The unattend.txt file is automatically created after installation.

[Data]

EMSPort

EMSBaudrate

Where,

EMSPort = Port used for serial communication. For example, COM1 or COM2.

EMSBaudrate = Configured baud rate for communication. The minimum supported baud rates for supported Dell™ PowerEdge™ systems is 19200.

Serial Console redirection With SOL Proxy

Configuring Linux for Serial Redirection During Boot

The "SysRq key" is a key sequence that allows basic commands to be passed directly to the kernel for debugging. Under some circumstances, it can also be used to reboot remote managed systems. The serial console uses the RS-232 break function as the SysRq key. A "break" is a period of no transmission on the serial line. To configure the "Sysrq" key in systems running Linux, follow the instructions given below:

NOTE: The following instructions are specific to the Linux GRand Unified Bootloader (GRUB). Similar changes would be necessary for using a different boot loader.

NOTE: In configuring the client VT100 emulation window, you must set the window or application that is displaying the redirected console to 25 rows x 80 columns to ensure proper text display; otherwise, some text screens may be garbled.

Edit the file /etc/grub.conf, as follows. See the sample file that follows, which shows the changes described in this procedure.

1. Add the following two new lines in the general settings section of the file:
   
   

serial --unit=0 --speed=19200
terminal --timeout=10 serial

2. Append two options to the kernel line:
   
   

kernel ............. console=ttyS0,19200

3. If the /etc/grub.conf contains a splashimage directive, you must comment it out.
   
   

This sample file, using a baud rate of 19200, is an example. The following maximum baud rates are allowed for BMC serial communication and SOL:

• 19200 for PowerEdge 1425SC and other PowerEdge x8xx systems.
  
  
• 57600 for PowerEdge x9xx and xx0x systems without Dell Remote Access Controller 5 (DRAC 5).
  
  
• 115200 for PowerEdge x9xx and xx0x systems with DRAC 5.
  
  

Table D-1. Sample File: /etc/grub.con

Additional information for editing the grub.conf:

1. You may need to disable GRUB's graphical interface and use the text-based interface instead; otherwise, the GRUB screen will not be displayed in BMU console redirection. To do so, comment out the line starting with splashimage.
   
   
2. If you have multiple options in GRUB and you want all of them to start a console session through the BMU serial connection, add console= ttyS1,19200 to all options. The preceding example shows console= ttyS0,19200 added to only the first option.
   
   

Enabling Login to the Console After Boot

Edit the file /etc/inittab, as follows:

Add a new line to configure a getty on the COM1 serial port:

co:2345:respawn:/sbin/agetty -h -L 19200 ttyS0 vt100

See the sample file, which shows the addition of the new line.

Table D-2. Sample File: /etc/innitab 

Edit the file /etc/securetty, as follows:

Add a new line, with the name of the serial tty for COM1:

ttyS0

See the sample file, which shows the addition of the new line.

Table D-3. Sample File: /etc/securetty

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