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How to setup serial console access in VMware to capture boot logs for troubleshooting

This document (7018394) is provided subject to the disclaimer at the end of this document.


SUSE Linux Enterprise Server 10 (all Service Packs)
SUSE Linux Enterprise Server 11 (all Service Packs)
SUSE Linux Enterprise Server 12 (all Service Packs)
SUSE Linux Enterprise Server 15 (all Service Packs)
VMware Workstation, ESX or ESXi


A virtualized system running on VMware Workstation, ESX or ESXi fails to boot. In order to proceed with troubleshooting support requested to capture the system messages for further analysis to see at which point of initialization the system fails.
The following steps will guide through the steps to connect a virtual serial console to the VM to save the kernel messages to a text file.


Instructions for ESXi:
  1. Shutdown the VM.
  2. Open the settings.
  3. Select the hardware tab and click "Add other device".
  4. Choose Serial Port .
  5. Expand the "New Serial port"
  6. Verify the path and filename are to your liking. ( Default path/file [VMNAME]/serial.out )
  7. If you need to set different path or filename .. click "Browse..." and choose a file location inside the VM folder on the datastore.
  8. Make sure the Serial Port gets connected once the machine powers on.
  9. Close the settings.
  10. Power on the virtual machine.
  11. At the boot prompt add the needed kernel options and hit enter.


Once the machine failed to boot, please check the file on the datastore if all messages from starting the kernel up to the error have been recorded and provide this file to support.

In case the file is empty, the serial port might have been connected to tty1/ttyS1 instead of tty0/ttyS0 as shown above. Please adjust the options if needed.


Instructions for VMware vCenter :

  1. Shutdown the VM.
  2. Right click and select Edit Settings.
  3. From the drop down menu of "New device" select Serial Port and hit Next.
  4. Now just select the file location on the datastore.
  5. Press OK
  6. Power on the virtual machine

It may be advised to increase the BIOS timeout to the virtual machine to its maximum of 10 seconds (10000 milliseconds) to gain more time to react.

In case there is no direct input possibility for the kernel options please select the matching entry on the screen, hit 'e' to edit and add the needed options to the line containing the root volume.

Additional Information

Useful debug kernel options for SLE11:
console=tty0 console=ttyS0,115200 debug ignore_loglevel
Useful debug kernel options for SLE12 and SLE 15:
systemd.log_level=debug systemd.log_target=console console=ttyS0,115200
Important: Starting with SLE 12 each installation adds the quiet option to the kernel options line to suppress messages during system boot. Please make sure this option gets removed when gathering boot debug information as systemd acts on this option as well and will provide less output.

Process has been verified to work with ESXi V7.0 Update 3j


This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.

  • Document ID:7018394
  • Creation Date: 15-Dec-2016
  • Modified Date:09-Jun-2023
    • SUSE Linux Enterprise Server

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