raspberrypi.mdwn

[[!meta title="Raspberry Pi"]]

* [General information](https://wiki.debian.org/RaspberryPi2).

Issues
======

## SSH

SSH not working by default on newer (2017) raspbian releases. That's because it's disabled
by default. Solution is to create a file called 'ssh' in the boot partition.

## Networking

* You might try to make it allways up with wicd-curses.

### Amplifier mode

Some references on using an external soundcard as an amplifier:

* packages: libncurses5-dev libjack-jackd2-dev jack-tools
* http://wiki.linuxaudio.org/wiki/raspberrypi
* http://www.jackaudio.org/applications/
* http://linux-audio.4202.n7.nabble.com/Solution-for-jackd2-and-dbus-without-X-session-td35904.html
* http://comments.gmane.org/gmane.linux.audio.users/82560
* [sound - How do I output my audio input? - Ask Ubuntu](https://askubuntu.com/questions/2719/how-do-i-output-my-audio-input)
* [Crackle-free audio on the Raspberry Pi with mpd and PulseAudio – dbader.org](https://dbader.org/blog/crackle-free-audio-on-the-raspberry-pi-with-mpd-and-pulseaudio)
* [How to play realtime insted of using arecord and aplay?](https://www.linuxquestions.org/questions/linux-newbie-8/how-to-play-realtime-insted-of-using-arecord-and-aplay-858500/)
* [Jackd Headless](https://capocasa.net/jackd-headless).

Attempts:

    man jack_disconnect 
    man jack_connect 
    man jack_lsp
    sudo jack_lsp
    sudo apt-get install jack-tools
    jackd
    jackd --no-realtime
    jackd --no-realtime -d alsa
    export DBUS_SESSION_BUS_ADDRESS=unix:path=/run/dbus/system_bus_socket jackd --no-realtime -d alsa
    DBUS_SESSION_BUS_ADDRESS=unix:path=/run/dbus/system_bus_socket jackd --no-realtime -d alsa
    sudo jackd --no-realtime -d alsa
    DBUS_SESSION_BUS_ADDRESS=unix:path=/run/dbus/system_bus_socket sudo jackd --no-realtime -d alsa
    sudo apt-get install libncurses5-dev libjack-jackd2-dev -y
    DBUS_SESSION_BUS_ADDRESS=unix:path=/run/dbus/system_bus_socket sudo jackd --no-realtime -d alsa
    DBUS_SESSION_BUS_ADDRESS=unix:path=/run/dbus/system_bus_socket sudo jackd -r -d alsa -d default:CARD=USB

### Freezing

At the serial console:

    [123916.394903] INFO: rcu_preempt detected stalls on CPUs/tasks:
    [123916.413406]         1: (1 GPs behind) idle=dcd/140000000000000/0 softirq=1003110/1003111 fqs=312910 
    [123916.447541]         (detected by 0, t=765007 jiffies, g=729122, c=729121, q=347657)
    [123916.467769] Task dump for CPU 1:
    [123916.484152] puppet          R running      0 29362      1 0x00000002
    [123916.503500] rcu_preempt kthread starved for 448421 jiffies!

References:

* [Pi2 rcu_preempt detected stalls · Issue #1161 · raspberrypi/linux · GitHub](https://github.com/raspberrypi/linux/issues/1161).

## Montagem automática de volume cifrado

Assumindo:

    VOLNAME: nome do disco externo
    MEDIA: nome do dispositivo mapeado (device mapper)

No TPC:

    dd if=/dev/urandom of=pirotron bs=1024 count=4
    keyringer $PROJECT encrypt disks/$MEDIA/luks/root-berry $VOLNAME
    scp $VOLNAME berry:~/
    wipe $VOLNAME

No raspberry:

    sudo mv /home/$USER/$VOLNAME /root/
    sudo chmod 0400 /root/$VOLNAME
    sudo cryptsetup luksAddKey /dev/sda1 /root/$VOLNAME

No `/etc/crypttab`:

    $VOLNAME        /dev/sda1               /root/$VOLNAME  luks

No `/etc/fstab`:

    /dev/mapper/$VOLNAME /media/$VOLNAME ext4    defaults          0       2

Referências:

* https://www.howtoforge.com/automatically-unlock-luks-encrypted-drives-with-a-keyfile
* https://askubuntu.com/questions/450895/mount-luks-encrypted-hard-drive-at-boot

## Rede

Arquivo `/etc/network/interfaces`:

    auto lo
    iface lo inet loopback

    #auto eth0
    #allow-hotplug eth0

    #iface eth0 inet manual
    #iface eth0 inet static
    #  address 192.168.0.100
    #  netmask 255.255.255.0

    auto wlan0
    allow-hotplug wlan0

    iface wlan0 inet static
      address 192.168.0.100
      netmask 255.255.255.0
      wpa-ssid ACCESS_POINT_NAME
      wpa-psk PSK
      #wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
      post-up /usr/sbin/service shorewall restart

    #iface wlan0 inet manual
    #  wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
    #
    #iface ape inet static
    #  address 192.168.0.100
    #  netmask 255.255.255.0

    #iface wlan0 inet manual
    #wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

    #auto wlan1
    #allow-hotplug wlan1
    #iface wlan1 inet manual
    #wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

Arquivo `/etc/wpa_supplicante/wpa_supplicant.conf` (por enquanto não utilizado):

    ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
    update_config=1

    network={
        ssid="ACCESS_POINT_NAME"
        psk="PSK"
    }

O esquema `wpa-roam` não funciona com interfaces `static`, então foi necessário usar [https://git.fluxo.info/?p=puppet-nodo.git;a=commit;h=d09f347afc0a99481673f227f83864d06206add6 um script].

Backups
-------

Fazendo o backup do cartão microSD a partir do TPC:

    dcfldd if=/dev/sdb | bzip2 > raspberry.img.bz2

## References

* http://linuxonflash.blogspot.com.br
* http://elinux.org/RPi_Serial_Connection
* https://www.raspbian.org/RaspbianMirrors