To install Gentoo this guide will be using the Alpine Extended ISO. It provides all of the necessary utilities for bootstrapping Gentoo. Make sure to boot with secureboot in setup mode or to already have keys ready to deploy.

After booting the Alpine Linux extended ISO, partition the disks. For this action internet is required since `zfs`, `sgdisk` and various other necessary packages are not included on the extended ISO, therefore they need to be obtained from the alpine package repository.

To set it up `setup-interfaces` and `setup-apkrepos` will be used.

``` shell-session
sh# setup-interfaces -ar
sh# setup-apkrepos -c1
```

> To use Wi-Fi simply run `setup-interfaces -r` and select `wlan0` or similar.

A few packages will have to be installed first:

``` shell-session
sh# apk add zfs lsblk sgdisk wipefs dosfstools zlevis
```

> The `zlevis` package is as of this moment not yet in the alpine package repository. Try to get it into the `bin` via a different method and add its dependencies `tpm2-tools` and `jose`. 

and load the ZFS kernel module:

``` shell-session
sh# modprobe zfs
```

Wipe the existing disk partitions:

``` shell-session
sh# zpool labelclear -f /dev/<disk>
sh# wipefs -a /dev/<disk>
sh# sgdisk --zap-all /dev/<disk>
```

Create on the disk an `EFI system` partition (ESP) and a `Linux filesystem` partition:

``` shell-session
sh# sgdisk -n 1:1m:+512m -t 1:ef00 /dev/<disk>
sh# sgdisk -n 2:0:-10m -t 2:8300 /dev/<disk>
```

Reload the device nodes:

``` shell-session
sh# mdev -s
```

Then, format the ESP with a FAT32 filesystem:

``` shell-session
sh# mkfs.fat -F 32 -n esp /dev/<disk>1
```

## ZFS pool creation

The ZFS system pool is going to be encrypted. First generate an encryption key and save it temporarily to the file `/tmp/rpool.key` with:

``` shell-session
sh# cat /dev/urandom | tr -dc 'a-zA-Z0-9' | fold -w 20 | head -n 1 > /tmp/rpool.key && cat /tmp/rpool.key
```

> While `zlevis` is used for automatic decryption, this key is required when making changes are made to the BIOS or secureboot, so make sure to save it.

Create the system pool:

``` shell-session
sh# zpool create -f \
        -o ashift=12 \
        -O compression=lz4 \
        -O acltype=posix \
        -O xattr=sa \
        -O dnodesize=auto \
        -O encryption=on \
        -O keyformat=passphrase \
        -O keylocation=prompt \
        -m none \
        rpool /dev/<disk>2
```

Then create the system datasets:

``` shell-session
sh# zfs create -o mountpoint=none rpool/root
sh# zfs create -o mountpoint=legacy -o quota=48g rpool/root/gentoo
sh# zfs create -o mountpoint=legacy -o quota=32g rpool/root/gentoo/var
sh# zfs create -o mountpoint=/home -o atime=off -o setuid=off -o devices=off -o quota=<home-quota> rpool/home
```

> Setting the `<home-quota>` depends on the total size of the pool, generally try to reserve some empty space in the pool.

Write the encryption key to TPM with `zlevis`:

``` shell-session
sh# zlevis encrypt rpool '{}' < /tmp/rpool.key
```

> We are using the default configuration settings for `zlevis encrypt` but a different configuration is possible by setting `'{}'` accordingly.


> To check if it worked, perform `zlevis decrypt rpool`.

Finally, export the zpool:

``` shell-session
sh# zpool export rpool
```