The Problem with Default Resolution

Oct 13, 2025 by wbrum.org 21 views

Introduction

When booting into a Linux system, the Kernel Mode Setting (KMS) driver often selects the highest resolution available on the display, which may not be the most suitable for reading or working. In this article, we will explore how to set a specific resolution for KMS at boot time, using Ubuntu and Kubuntu as examples.

Understanding KMS

KMS is a graphics driver that allows the kernel to communicate directly with the graphics card, providing a more efficient and flexible way of managing display settings. One of the benefits of KMS is that it allows the kernel to automatically detect and configure the display settings, including resolution, refresh rate, and color depth.

The Problem with Default Resolution

While KMS's ability to automatically detect and configure display settings is convenient, it can sometimes lead to issues. In particular, when the highest resolution available is selected, it can be difficult to read or work on the system, especially if the display is not designed for high-resolution output.

Setting a Specific Resolution for KMS

To set a specific resolution for KMS at boot time, you will need to modify the kernel command line. This can be done by editing the GRUB configuration file or by using a tool like grub-customizer.

Editing the GRUB Configuration File

To edit the GRUB configuration file, you will need to open the file in a text editor as root. The file is usually located at /etc/default/grub.

sudo nano /etc/default/grub

Once you have opened the file, you will need to locate the line that starts with GRUB_CMDLINE_LINUX. This line contains the kernel command line, which is used to pass options to the kernel at boot time.

# GRUB_CMDLINE_LINUX="quiet splash"

To set a specific resolution for KMS, you will need to add the video option to the kernel command line. The video option is used to specify the video mode, including resolution, refresh rate, and color depth.

# GRUB_CMDLINE_LINUX="quiet splash video=1440x900"

Once you have added the video option, you will need to save the file and update the GRUB configuration.

sudo update-grub

Using grub-customizer

If you prefer to use a graphical tool to edit the GRUB configuration, you can use grub-customizer. This tool provides a user-friendly interface for editing the GRUB configuration, including the kernel command line.

sudo apt-get install grub-customizer

Once you have installed grub-customizer, you can launch the tool and edit the kernel command line.

sudo grub-customizer

Verifying the Resolution

Once you have modified the kernel command line, you will need to verify that the resolution has been set correctly. You can do this by checking the display settings in the system settings or by using the xrandr command.

xrandr -q

This command will display the current display settings, including the resolution.

Conclusion

In this article, we have explored how to set a specific resolution for KMS at boot time, using Ubuntu and Kubuntu as examples. By modifying the kernel command line, you can specify the resolution, refresh rate, and color depth for the display. We have also discussed how to use grub-customizer to edit the GRUB configuration in a graphical interface.

Troubleshooting

If you encounter any issues when setting a specific resolution for KMS, you can try the following troubleshooting steps:

Check the kernel command line to ensure that the video option is correctly specified.
Verify that the display settings are correctly configured in the system settings.
Use the xrandr command to check the current display settings.
Try setting a different resolution to see if the issue is specific to the chosen resolution.

Additional Resources

For more information on setting a specific resolution for KMS, you can refer to the following resources:

Q: What is KMS and why is it used?

A: KMS stands for Kernel Mode Setting, which is a graphics driver that allows the kernel to communicate directly with the graphics card. KMS is used to provide a more efficient and flexible way of managing display settings, including resolution, refresh rate, and color depth.

Q: Why does KMS choose the highest resolution available?

A: KMS chooses the highest resolution available because it is designed to automatically detect and configure the display settings. This can sometimes lead to issues, especially if the display is not designed for high-resolution output.

Q: How do I set a specific resolution for KMS at boot time?

A: To set a specific resolution for KMS at boot time, you will need to modify the kernel command line. This can be done by editing the GRUB configuration file or by using a tool like grub-customizer.

Q: What is the `video` option and how do I use it?

A: The video option is used to specify the video mode, including resolution, refresh rate, and color depth. To use the video option, you will need to add it to the kernel command line in the GRUB configuration file.

Q: How do I add the `video` option to the kernel command line?

A: To add the video option to the kernel command line, you will need to edit the GRUB configuration file and add the video option to the line that starts with GRUB_CMDLINE_LINUX.

Q: What is the format of the `video` option?

A: The format of the video option is video=<resolution>, where <resolution> is the desired resolution. For example, to set a resolution of 1440x900, you would use the following format: video=1440x900.

Q: Can I use other options with the `video` option?

A: Yes, you can use other options with the video option. For example, you can specify the refresh rate and color depth using the following format: video=1440x900@60,32.

Q: How do I verify that the resolution has been set correctly?

A: To verify that the resolution has been set correctly, you can use the xrandr command to check the current display settings.

Q: What are some common issues that I may encounter when setting a specific resolution for KMS?

A: Some common issues that you may encounter when setting a specific resolution for KMS include:

The display settings not being applied correctly
The display settings being overridden by the graphics card
The display settings not being supported by the graphics card

Q: How do I troubleshoot issues with setting a specific resolution for KMS?

A: To troubleshoot issues with setting a specific resolution for KMS, you can try the following steps:

Check the kernel command line to ensure that the video option is correctly specified
Verify that the display settings are correctly configured in the system settings
Use the xrandr command to check the current display settings
Try setting a different resolution to see if the issue is specific to the chosen resolution

Q: Are there any additional resources that I can use to learn more about setting a specific resolution for KMS?

A: Yes, there are several additional resources that you can use to learn more about setting a specific resolution for KMS, including:

The Kernel Mode Setting (KMS) documentation
The GRUB configuration file documentation
The xrandr command documentation

By following the steps outlined in this article and using the Q&A section to troubleshoot any issues that you may encounter, you should be able to set a specific resolution for KMS at boot time.