azusa

RPi Model 3B+ (aarch64, 4-core, 1gb RAM)
RPi OS Lite 64-bit (Bookworm)
LAN MAC b8:27:eb:8c:f4:f8
located at home

Contents

azusa
1. Build notes

Build notes

This is the most generic stuff to do for initial setup, before tweaking it to a specific use.

OS imaging

Using the Raspberry Pi Imager app, start with the current RPi OS Lite 64-bit, which is Debian bookwork 12.2, suitable for the RPi 3B+

It lets you make some customisations before flashing, which is really nice:

Set hostname to azusa
Enable SSH
- Password auth (I would use SSH keys but it didn't work right for me and I couldn't sudo later)
Set username and password
- furinkan // <something new>
No WLAN
Set locale to Australia/Sydney, us keyboard
Disable telemetry

Prepare DHCP server with static address for the LAN MAC address (should already be in place).

Put in the card and let it boot, should be fairly quick.

First login

ssh-keygen -t ed25519
# Enter 3 times

touch ~/.ssh/authorized_keys
chmod 0600 ~/.ssh/authorized_keys
vi ~/.ssh/authorized_keys

sudo up and copy your SSH key to root's account as well, use the same commands again
Login again directly as root
Install base packages
```
apt install -y vim git screen ack
```
Edit /etc/pam.d/sshd and remove user_readenv=1, this will keep the logs tidy

Configure vim

cat <<EOF > ~/.vimrc
set nocompatible
syntax on
set background=dark
set hlsearch
set modeline
set scrolloff=3
EOF

Configure shell
- Edit /root/.bashrc to enable colours
- Set the default editor to vim.basic:
```
update-alternatives --config editor
```

Disable wifi and bluetooth and other stuff

I'm using azusa as a network appliance, so I don't need the radios: https://sleeplessbeastie.eu/2018/12/31/how-to-disable-onboard-wifi-and-bluetooth-on-raspberry-pi-3/

Also see the notes for RPi4, because the OS has changed in the meantime too: https://sleeplessbeastie.eu/2022/06/01/how-to-disable-onboard-wifi-and-bluetooth-on-raspberry-pi-4/

Add dtoverlays to your /boot/config.txt to disable the radios:

cat <<EOF >> /boot/config.txt
dtoverlay=disable-wifi
dtoverlay=disable-bt
EOF

Let's also disable sound

sed -r -i 's,^dtparam=audio=on$,dtparam=audio=off,' /boot/config.txt

Disable bluetooth and modem services

systemctl disable --now hciuart
systemctl disable --now bluetooth.target
systemctl disable --now bluetooth.service
systemctl disable --now ModemManager.service

Nuke the software packages as well

apt purge -y bluez bluez-firmware wpasupplicant
rm -rfv /etc/wpa_supplicant
apt autoremove -y

No keyboard means no hotkeys needed
```
apt purge -y triggerhappy
```
Reboot

Fix IPv6 SLAAC address

WhyTF am I not getting an EUI-64-based IPv6 SLAAC address now? It's worked every time before. Looks like our network config uses NetworkManager, so we need to configure that. It seems like it's not using privacy addresses, but it is doing stable-privacy now, which I don't want.

cat <<EOF > /etc/NetworkManager/conf.d/ip6-privacy.conf
[connection]
ipv6.ip6-privacy=0
ipv6.addr-gen-mode=0
EOF

Then reboot again.

The mode is now "default" instead of "eui64" as I would've expected (nmcli connection show Wired\ connection\ 1 | grep addr-gen), and I've no idea what that default is, but I don't care because it works now.

Read here for references:

Other tweaks

Using raspi-config:
- System -> Audio -> pass out through HDMI
- Display -> Screen blanking -> Disable it
- Then exit and let it reboot

Configure screen

curl -o ~/.screenrc https://gist.githubusercontent.com/barneydesmond/d16c5201ed9d2280251dfca7c620bb86/raw/.screenrc

Configure top: z x c s 1.5 <Enter> e 0 1 W q

Configure hardware RTC

I've installed the Jaycar XC-9044 RPi realtime clock RTC, it's apparently a good clock chip with a little battery (or something). Most models using this chip have a spot for a watch battery, but this one has a tiiiiny little thing soldered on the board. I hope it's decent.

Physically install the module on the 3V3 plus I2C pins
Enable i2c with raspi-config, it's in Interface Options -> I2C -> Enable
- You can also do it yourself if you want:
  1. Comment out any blacklist entries for i2c[-_]bcm2708 in /etc/modprobe.d/raspi-blacklist.conf
  2. Load the module at boot:
```
echo i2c-dev >> /etc/modules
```
  3. Uncomment/add dtparam=i2c_arm=on in /boot/config.txt
  4. Activate it now:
```
modprobe i2c-dev
```
Reboot now, it can't hurt
Install i2c tools
```
apt install -y i2c-tools
```
Detect the device on i2c bus: i2cdetect -y 1
- Should appear at 0x68
Enable the kernel driver for it, or something, by adding a devicetree overlay
```
echo "dtoverlay=i2c-rtc,ds3231" >> /boot/config.txt
```
Reboot again to load the device tree overlay that we just configured
Again detect the device on i2c bus: i2cdetect -y 1
- Should appear at 0x68, BUT with "UU" at the address this time

Remove the fake hardware clock

systemctl disable fake-hwclock --now
apt purge -y fake-hwclock

In theory everything just works now thanks to a udev rule: https://www.raspberrypi.org/forums/viewtopic.php?t=209700

root@azusa:~# cat /lib/udev/rules.d/85-hwclock.rules
# Set the System Time from the Hardware Clock and set the kernel's timezone
# value to the local timezone when the kernel clock module is loaded.
KERNEL=="rtc0", RUN+="/usr/lib/udev/hwclock-set $root/$name"

Install chrony so it manages the hardware clock
```
apt install -y chrony
```
It'll do the rest once it's installed and synced. Try some commands to see how it's fairing:
```
chronyc sources
chronyc tracking
```

Save a copy

Optionally take a backup image of the fully configured system, by putting the card in another machine and shrinking the filesystem

e2fsck -f /dev/mmcblk0p2
resize2fs /dev/mmcblk0p2 2G
dd bs=4M count=600 if=/dev/mmcblk0 | pv -br | pigz --fast > "$(date +%Y-%m-%d)_azusa_pristine_config.img.gz"

Useful(?) links

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