This document is a guide for installing Arch Linux ARM on the Helios4.

## What you need before you start

Look at the "[What you need before you start](/install/#what-you-need-before-you-start)" section of the Helios4 install guide.

## Using an Arch Linux ARM image file for Helios4

Arch Linux ARM can be installed on Helios4 using an image file containing both the **Arch Linux ARM system** and the **U-Boot** boot loader.

This image can be created using the `build-archlinux-img-for-helios4.sh` script provided by the [alarm-helios4-image-builder](https://github.com/gbcreation/alarm-helios4-image-builder) project, or you can use a pre-built image from the same project. Each method is described below.

Once you get an image file, follow the instructions from the [Installing Arch Linux ARM on Helios4](#installing-arch-linux-arm-on-helios4) section below.

### The Arch Linux ARM image builder for Helios4

The `build-archlinux-img-for-helios4.sh` script provided by the [alarm-helios4-image-builder](https://github.com/gbcreation/alarm-helios4-image-builder) project allows to create a bootable Arch Linux ARM image file for Helios4 automatically.

#### Requirements

The `build-archlinux-img-for-helios4.sh` script expects to be used on a **x86 system running [Arch Linux](https://archlinux.org)**. It needs `qemu-arm-static` to work. You can install it using the [qemu-user-static](https://aur.archlinux.org/packages/qemu-user-static/) or [qemu-user-static-bin](https://aur.archlinux.org/packages/qemu-user-static-bin/) packages from the AUR.

#### Usage

!!! note
    This script needs to execute commands as the superuser. If not run as root, it will re-run itself using sudo.

```shell
$ git clone https://github.com/gbcreation/alarm-helios4-image-builder.git
$ cd alarm-helios4-image-builder
$ sh ./build-archlinux-img-for-helios4.sh
```

Once the Arch Linux ARM image created, follow the instructions from the [Installing Arch Linux ARM on Helios4](#installing-arch-linux-arm-on-helios4) section below.

### Pre-built images

You can download a pre-built Arch Linux ARM image for Helios4 from the [alarm-helios4-img-builder](https://github.com/gbcreation/alarm-helios4-image-builder/releases) project.

```shell
$ wget https://github.com/gbcreation/alarm-helios4-image-builder/releases/download/2019-02-27/ArchLinuxARM-helios4-2019-02-27.img.gz{,.md5}
$ md5sum -c ArchLinuxARM-helios4-2019-02-27.img.gz.md5
$ gunzip ArchLinuxARM-helios4-2019-02-27.img.gz
```

## Installing Arch Linux ARM on Helios4

Once you get an Arch Linux ARM image, follows these instructions to use it on Helios4:

### Writing image / power-up Helios4 / connecting to serial console

Follows these steps from the [Helios4 install guide](/install):

- [step 2](/install/#step-2-writing-an-image-to-a-microsd-card) to write the Arch Linux ARM image to a microSD card
- [step 3](/install/#step-3-power-up-helios4) to power-up Helios4
- [step 4](/install/#step-4-connect-to-helios4-serial-console) to connect to the Helios4 serial console. 

!!! note
    Arch Linux ARM is configured by default to get its IP address from a DHCP server. As an alternative to **step 4**, you can connect to your router to find the IP address given to Helios4, then connect to this latter using SSH.

### Log in

Use the serial console or SSH to the IP address given to Helios4 by your router.

You can login as:

- the default user *alarm* with the password *alarm*
- the user *root* with password *root*

!!! important
    For security reasons, it is highly recommended to change the default password of the **alarm** and **root** users.

### Network settings

Arch Linux ARM is configured by default to get its IP address from a DHCP server. To change the network settings, look at the [Network Configuration](https://wiki.archlinux.org/index.php/Network_configuration) page from the Arch Linux wiki.

### Pacman

The Pacman keyring is already initialized in the images created by the `build-archlinux-img-for-helios4.sh` script and the pre-built images. It is also already populated with the Arch Linux ARM package signing keys.

## What to do next?

You can now configure Arch Linux ARM according to you needs and use **pacman** to install third party applications.

Here are some useful links from the [Arch Linux wiki](https://wiki.archlinux.org) to get started:

- [RAID](https://wiki.archlinux.org/index.php/RAID)
- [dm-crypt/Device encryption](https://wiki.archlinux.org/index.php/Dm-crypt/Device_encryption).

!!! note
    Read the [Accelerate Disk Encryption](/cesa/#accelerate-disk-encryption) section of the Helios4 wiki before proceeding to learn how to offload disk encryption on the CESA unit.

- [Nextcloud](https://wiki.archlinux.org/index.php/Nextcloud)
- [NFS](https://wiki.archlinux.org/index.php/NFS)
- [Samba](https://wiki.archlinux.org/index.php/Samba)