How to Use a Japanese Keyboard (JIS Layout) in GRUB: Rocky Linux / RHEL Compatible

When working with the GRUB menu or command line, you may encounter issues where the keyboard is treated as a US layout.

This is particularly problematic with Japanese keyboards, as:

• @
• :
• "
• \
• _

These symbols are located in different positions on US and JIS layouts, making it quite inconvenient to edit kernel parameters or enter commands in GRUB.

This article summarizes how to change the GRUB keyboard layout to the Japanese JIS layout on RHEL-based Linux distributions such as Rocky Linux, AlmaLinux, RHEL, and CentOS Stream.

Note that the “Japanese keyboard” referred to here does not refer to the Japanese input IME. It is not intended to enable Japanese character input in GRUB, but rather to configure it to match the physical key layout of a JIS keyboard.

Linux Keyboard Settings and GRUB Keyboard Settings Are Different

Normally, you can change the Linux console keymap with the following command:

localectl set-keymap jp

Alternatively, you can specify it in the kernel parameters or configuration file, such as:

vconsole.keymap=jp

However, these are settings that take effect after the Linux kernel has booted.

Since GRUB runs before Linux, the Linux keyboard settings are not reflected in GRUB.

In other words, in the boot sequence:

GRUB
  ↓
Linux kernel
  ↓
systemd / console

The keyboard layout for GRUB must be configured within GRUB itself.

Packages Required for Rocky Linux / RHEL

In Rocky Linux and RHEL-based systems, GRUB-related commands have grub2- prefixes.

Install the necessary packages:

sudo dnf install grub2-tools-extra kbd

The following commands are mainly used:

grub2-kbdcomp
grub2-mkconfig

Use grub2-kbdcomp to create a keyboard layout file that GRUB can read.

Create a Japanese Keymap for GRUB

First, create a save location:

sudo mkdir -p /boot/grub2/layouts

Next, create the Japanese JIS layout keymap:

sudo grub2-kbdcomp -o /boot/grub2/layouts/jp.gkb jp

Verify that it was created:

ls -l /boot/grub2/layouts/jp.gkb

If a file exists as follows, the preparation is complete:

/boot/grub2/layouts/jp.gkb

In GRUB, the keyboard layout is changed by loading this .gkb file.

Temporarily Change to JIS Layout Only During GRUB Boot

Instead of making a permanent change all at once, it is recommended to first load it temporarily from the GRUB command line and verify that it works.

When the GRUB menu is displayed, press:

c

to enter the GRUB command line.

Execute the following command:

insmod keylayouts
keymap jp

This will change to the Japanese JIS layout for that GRUB session only.

Since it will revert to the original upon reboot, it is suitable for testing the settings.

If keymap jp Cannot Be Loaded

Check the prefix used by GRUB:

echo $prefix

For example, it may display:

(hd0,gpt2)/grub2

Next, check if the keymap is visible:

ls $prefix/layouts/

If:

jp.gkb

is displayed, GRUB can access the file.

In this case, it should normally be loaded with:

keymap jp

Depending on the environment, you may want to explicitly specify the file to confirm:

keymap $prefix/layouts/jp.gkb

Make the JIS Layout Permanent

Once you have verified that it works, incorporate it into the GRUB configuration.

On RHEL-based systems, appending to /etc/grub.d/40_custom is a clear method.

sudo vi /etc/grub.d/40_custom

Add the following content:

insmod keylayouts
keymap ${prefix}/layouts/jp.gkb

Alternatively, depending on the environment, the following specification may also work:

insmod keylayouts
keymap jp

Personally, I prefer to explicitly specify it so that it is clear which file is being used:

keymap ${prefix}/layouts/jp.gkb

This makes it easier to troubleshoot.

Regenerate grub.cfg

After changing the settings, regenerate the GRUB configuration.

On newer RHEL-based systems such as Rocky Linux 9:

sudo grub2-mkconfig -o /boot/grub2/grub.cfg

Reboot:

sudo reboot

In the GRUB menu, press c to open the command line and check the symbol keys.

For example:

@
:
"
\
_

If these can be entered as they are printed on the keycaps, the JIS layout has been applied.

Notes for UEFI Environments

Older articles mention examples of running grub2-mkconfig directly on the following file in UEFI environments:

/boot/efi/EFI/redhat/grub.cfg

In Rocky Linux, it may be:

/boot/efi/EFI/rocky/grub.cfg

However, in recent RHEL-based systems, the UEFI grub.cfg is configured to be used as a stub to load the main /boot/grub2/grub.cfg.

Therefore, in Rocky Linux 9 and later, it is generally recommended to use:

sudo grub2-mkconfig -o /boot/grub2/grub.cfg

It is safer not to directly overwrite the UEFI grub.cfg unnecessarily.

Is terminal_input at_keyboard Necessary?

In GRUB keyboard configuration examples, you may see settings like:

insmod at_keyboard
terminal_input at_keyboard

However, on USB keyboards and UEFI environments, explicitly switching the input path to at_keyboard may prevent keyboard input.

If you only want to change to the JIS layout, it is safest to first try:

insmod keylayouts
keymap ${prefix}/layouts/jp.gkb

Unless there is a specific reason, it is not necessary to change the input terminal itself.

Temporary Change vs. Permanent Change

To summarize, the following applies:

It is safe to test with a temporary change first, and then make it permanent if there are no problems.

Can I Change to the JIS Layout in GRUB Without Creating a .gkb File?

Basically, no.

The keymap command in GRUB is designed to load pre-created GRUB keyboard layout files.

Therefore, during Linux startup, you need to:

grub2-kbdcomp

to create:

jp.gkb

in advance.

At a minimum, you need to perform the following preparations on the Linux side:

sudo mkdir -p /boot/grub2/layouts
sudo grub2-kbdcomp -o /boot/grub2/layouts/jp.gkb jp

After that, you can always run:

insmod keylayouts
keymap jp

in the GRUB command line to temporarily switch to the JIS layout.

Summary

When setting GRUB to a Japanese JIS keyboard layout on Rocky Linux or RHEL, the key points are:

1. First, create a GRUB keymap:

   sudo dnf install grub2-tools-extra kbd
   sudo mkdir -p /boot/grub2/layouts
   sudo grub2-kbdcomp -o /boot/grub2/layouts/jp.gkb jp

2. If you want to try it temporarily in GRUB:

   insmod keylayouts
   keymap jp

3. To make it permanent, add to /etc/grub.d/40_custom:

   insmod keylayouts
   keymap ${prefix}/layouts/jp.gkb

   and run:

   sudo grub2-mkconfig -o /boot/grub2/grub.cfg

GRUB runs before Linux boots, so the localectl set-keymap jp and other Linux settings are completely separate.

If you frequently edit kernel parameters or perform rescue operations in GRUB, setting up the JIS keyboard will make it much easier to operate.