# How to enable Real-time kernel

```{caution}
Real-Time Kernel is only supported on 22.04. For more information, please see
https://ubuntu.com/realtime-kernel
```

## Enable and auto-install

To `enable` Real-Time Kernel through Ubuntu Advantage, please run:

```console
$ sudo pro enable realtime-kernel
```

You'll need to acknowledge a warning, and then you should see output like the
following, indicating that the Real-Time Kernel package has been installed.

```
One moment, checking your subscription first
The Real-time kernel is a beta version of the 22.04 Ubuntu kernel with the
PREEMPT_RT patchset integrated for x86_64 and ARM64.

This will change your kernel. You will need to manually configure grub to
revert back to your original kernel after enabling real-time.

Do you want to continue? [ default = Yes ]: (Y/n) yes
Updating package lists
Installing Real-time kernel packages
Real-time kernel enabled
A reboot is required to complete install.
```

After rebooting you'll be running the Real-time kernel!

## Enable and manually install

```{important}
The --access-only flag is introduced in version 27.11
```

If you would like to enable access to the Real-Time Kernel APT repository but
not install the kernel right away, use the `--access-only` flag while enabling.

```console
$ sudo pro enable realtime-kernel --access-only
```

With this extra flag you'll see output like the following:

```
One moment, checking your subscription first
Updating package lists
Skipping installing packages: ubuntu-realtime
Real-time kernel access enabled
```

To install the kernel you can then run:

```console
$ sudo apt install ubuntu-realtime
```

You'll need to reboot after installing to boot into the Real-time kernel.
