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ESXi enhancement for Headless System Support in ESXi 5.5 Update 1 (2075033)

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Details

 This article provides information about ESXi enhancement for Headless System Support

Solution

ESXi automatically switches its console service from running on a VGA device to a serial port if the appropriate system configuration is detected in the hardware. The sections mentioned below explain the new behavior in ESXi that provides support for headless system.

  • What system configuration triggers ESXi to switch its console to a serial port?

    During system boot up, if ESXi finds No VGA Present or Headless flag set in ACPI FADT table and if there is no user specified change in any of the serial services, the DCUI service will display on a serial port.

    Note: Headless support is applicable only for headless systems with proper settings in ACPI FADT table. Serial support is applicable for any system.

  • Which serial port is selected for the console?

    By default, ESXi uses the serial port that is designated as COM1 for the console. The settings of COM1 is obtained from the ACPI SPCR table. ESXi sets the baudrate to 115200.

  • How to workaround with the lack of functions keys (F1 - F12) on some serial terminal emulation software?

    The function keys are mapped to the following keystroke sequence by DCUI.

    Function Keys
    Sequence
    F1
    Esc 1
    F2
    Esc 2
    F3
    Esc 3
    F4
    Esc 4
    F5
    Esc 5
    F6
    Esc 6
    F7
    Esc 7
    F8
    Esc 8
    F9
    Esc 9
    F10
    Esc 0
    F11
    Esc !
    F12
    Esc @

  • How does the console share the serial port with other existing services that use the same serial port?

    ESXi has 3 other serial services besides DCUI. They are services for Log, Shell, and Debug. At any one point, only one serial service is connected to a serial port. To get access to other serial services, the user can use the following keystroke sequence to switch to the desired serial service.

    Services
    Sequence
    Log
    Ctrl-g Ctrl-b 1
    Shell
    Ctrl-g Ctrl-b 2
    DCUI
    Ctrl-g Ctrl-b 3
    GDB
    Ctrl-g Ctrl-b ?

    Note: If you use keystroke sequence to switch to the GDB service, you cannot use keystroke sequence to switch to other service anymore. You will need to use the shell command to make the switch. In this scenario, you will need to remotely logon to ESXi to issue the shell command.

    If the target serial service is already running on a different serial port then the switch is ignored, the serial services are only allowed to run on one serial port at a time. You can also switch a serial port to another service using an ESXi shell command.

    Services
    Commands
    Log
    esxcfg-advcfg -s <COM port> /Misc/LogPort
    Shell
    esxcfg-advcfg -s <COM port> /Misc/ShellPort
    DCUI
    esxcfg-advcfg -s <COM port> /Misc/ConsolePort
    GDB
    esxcfg-advcfg -s <COM port> /Misc/GDBPort

    <COM port> is either com1 or com2.

    Note: Before switching to a serial port to another service using an ESXi shell command, set the current mode to None.

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