# Change page size on Ubuntu

## In this learning path

- [Introduction](https://learn.arm.com/learning-paths/servers-and-cloud-computing/arm_linux_page_size/)
- [Overview](https://learn.arm.com/learning-paths/servers-and-cloud-computing/arm_linux_page_size/overview/)
- [Change page size on Ubuntu](https://learn.arm.com/learning-paths/servers-and-cloud-computing/arm_linux_page_size/ubuntu/)
- [Change page size on Debian](https://learn.arm.com/learning-paths/servers-and-cloud-computing/arm_linux_page_size/debian/)
- [Change page size on CentOS](https://learn.arm.com/learning-paths/servers-and-cloud-computing/arm_linux_page_size/centos/)
- [Next Steps](https://learn.arm.com/learning-paths/servers-and-cloud-computing/arm_linux_page_size/_next-steps/)

To install a 64 K page size kernel on [Ubuntu 22.04 LTS or later](https://releases.ubuntu.com/22.04/), follow the steps below.

## Verify the current page size

Verify you’re using a 4KB base-page-size kernel by entering the following commands:

```
getconf PAGESIZE
uname -r
```

The output should be similar to below. The kernel flavor (the string after the version number) may vary, but the first line should always be 4096.

```
__output__ 4096
__output__ 6.1.0-34-cloud-arm64
```

The 4096 indicates the current page size is 4 KB. If you see a value that is different, you are already using a page size other than 4096 (4K). On Arm systems, the valid options are 4K, 16K, and 64K.

## Install the required dependencies and the 64K kernel

Run the commands to install the required software:

```
sudo apt-get -y update
sudo apt-get -y install git build-essential autoconf automake libtool gdb wget linux-generic-64k
```

Next, run the following command to configure GRUB to load the 64K kernel by default:

```
echo "GRUB_FLAVOUR_ORDER=generic-64k" | sudo tee /etc/default/grub.d/local-order.cfg
```

## Update GRUB and reboot

Commit your changes to GRUB and reboot by entering the following:

```
sudo update-grub
sudo reboot
```

Upon reboot, check the kernel page size and name to confirm the changes:

```
getconf PAGESIZE
uname -r
```

The output shows the 64K kernel is running:

```
__output__ 65536
__output__ 6.8.0-59-generic-64k
```

This indicates that the current page size is 64K and that you are running the new 64K kernel.

## Revert to the 4K kernel

To revert to the original 4K kernel, run the following commands:

```
echo "GRUB_FLAVOUR_ORDER=generic" | sudo tee /etc/default/grub.d/local-order.cfg
sudo update-grub
sudo reboot
```

Upon reboot, verify you’re on a 4KB pagesize kernel by entering the following commands:

```
getconf PAGESIZE
uname -r
```

The output shows the 4K kernel is running:

```
__output__ 4096
__output__ 6.1.0-34-cloud-arm64
```

The 4096 indicates the current page size has been reverted to 4KB.