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raspberrypi.rst

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Configuration tweaks on a Raspberry Pi

Raspbian installation

Download Raspbian image from http://www.raspberrypi.org/downloads.

Each time the SD card is mounted and files modified, /etc/fake-hwtime or /etc/fake-hwclock.data needs to be updated with current date and time in YYYY-MM-DD HH:MM:SS format. Otherwise the system may experience some timing-related issues (and fails to mount the root filesystem). This can be done with:

date '+%Y-%m-%d %H:%M:%S' > /etc/fake-hwclock.data

You may run the system on the SD card in QEMU if you don't have an HDMI screen. http://xecdesign.com/qemu-emulating-raspberry-pi-the-easy-way/ describes how to achieve that, by downloading a special kernel of qemu-arm and running:

qemu-system-arm -kernel kernel-qemu -cpu arm1176 -m 256 -M versatilepb \
    -no-reboot -serial stdio -append "root=/dev/sda2 panic=1" -hda /dev/sdb

This kernel has been compiled with instructions written on http://xecdesign.com/compiling-a-kernel/. It is configured to build a kernel for an ARM11 (ARMv6) versatile board, which requires a patch to be applied: http://xecdesign.com/downloads/linux-qemu/linux-arm.patch

Post-install configuration

Like all Debian systems, some files needs updating after the initial setup:

  • /etc/mailname (with the name to be used in mailing)
  • /etc/sudoers (remove pi ALL=(ALL) NOPASSWD: ALL)
  • /etc/ntp.conf (remove restrict ::1 if IPv6 module is not loaded)
  • Reconfigure the keyboard: keyboard-configuration
  • Change timezone: tzselect (TZ='Europe/Paris'; export TZ)

Moreover, /etc/sysctl.conf contains Raspberry Pi-specific configuration:

# rpi tweaks
vm.swappiness=1
vm.min_free_kbytes = 8192

Networking

/etc/network/interfaces with a dynamic configuration:

auto lo
# Add contents:
allow-hotplug eth0

iface lo inet loopback
iface eth0 inet dhcp

allow-hotplug wlan0
iface wlan0 inet manual
wpa-roam /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

Static configuration may be used with the following lines:

iface eth0 inet static
    address 192.0.2.2
    netmask 255.255.255.0
    gateway 192.0.2.1

Enable IPv6

To enable IPv6, use the following commands:

modprobe ipv6
sysctl -w net.ipv6.conf.default.use_tempaddr=2
sysctl -w net.ipv6.conf.all.use_tempaddr=2

To make these changes persistent, add ipv6 to /etc/modules and net.ipv6.conf.default.use_tempaddr = 2 to /etc/sysctl.conf.

Some useful system information

Here are the outputs of several commands to retrieve system information on a Raspberry Pi, model B.

  • As some people consider a Serial Number and a MAC address as being sensitive information, each potential sensitive hexadecimal byte has been replaced here by XX.
  • Information about used kernel is not relevant here. So these outputs don't include kernel version and kernel pointers have been protected (sysctl -w kernel.kptr_restrict=2).
  • Address space is randomized (ALSR, sysctl -w kernel.randomize_va_space=2) so when dumping /proc/*/maps, random parts of addresses have been replaced by X.
$ uname -m
armv6l

$ cat /proc/cpuinfo
processor   : 0
model name  : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS    : 2.00
Features    : swp half thumb fastmult vfp edsp java tls
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x0
CPU part    : 0xb76
CPU revision    : 7

Hardware    : BCM2708
Revision    : 000f
Serial      : 00000000XXXXXXXX

$ cat /proc/cmdline | fmt -80
dma.dmachans=0x7f35 bcm2708_fb.fbwidth=656
bcm2708_fb.fbheight=416 bcm2708.boardrev=0xf bcm2708.serial=0xXXXXXXXX
smsc95xx.macaddr=B8:27:XX:XX:XX:XX sdhci-bcm2708.emmc_clock_freq=100000000
vc_mem.mem_base=0x1ec00000 vc_mem.mem_size=0x20000000  dwc_otg.lpm_enable=0
console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2
rootfstype=ext4 elevator=deadline rootwait

$ cat /proc/modules
ipv6 278186 32 - Live 0x00000000
snd_bcm2835 16304 0 - Live 0x00000000
snd_pcm 77560 1 snd_bcm2835, Live 0x00000000
snd_seq 53329 0 - Live 0x00000000
snd_timer 19998 2 snd_pcm,snd_seq, Live 0x00000000
snd_seq_device 6438 1 snd_seq, Live 0x00000000
snd 58447 5 snd_bcm2835,snd_pcm,snd_seq,snd_timer,snd_seq_device, Live 0x00000000
snd_page_alloc 5145 1 snd_pcm, Live 0x00000000
leds_gpio 2235 0 - Live 0x00000000
led_class 3562 1 leds_gpio, Live 0x00000000

$ gcc -E -v - < /dev/null 2>&1 | grep cc1 | fmt -80
/usr/lib/gcc/arm-linux-gnueabihf/4.6/cc1 -E -quiet -v -imultilib
. -imultiarch arm-linux-gnueabihf - -march=armv6 -mfloat-abi=hard -mfpu=vfp

$ cat /proc/self/maps | tail -n2
beXXX000-beXXX000 rw-p 00000000 00:00 0          [stack]
ffff0000-ffff1000 r-xp 00000000 00:00 0          [vectors]

$ lsusb
Bus 001 Device 002: ID 0424:9512 Standard Microsystems Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp.

$ readlink /sys/class/net/eth0
../../devices/platform/bcm2708_usb/usb1/1-1/1-1.1/1-1.1:1.0/net/eth0
$ readlink /sys/devices/platform/bcm2708_usb/usb1/1-1/1-1.1/1-1.1:1.0/driver
../../../../../../../bus/usb/drivers/smsc95xx
$ dmesg | grep eth0 | head -n1 | tail -c+16
smsc95xx 1-1.1:1.0: eth0: register 'smsc95xx' at usb-bcm2708_usb-1.1, smsc95xx USB 2.0 Ethernet, b8:27:XX:XX:XX:XX

$ lshw | fmt -80 -s
raspberrypi
    description: Computer
    width: 32 bits
  *-core
       description: Motherboard
       physical id: 0
     *-memory
          description: System memory
          physical id: 0
          size: 438MiB
     *-cpu
          physical id: 1
          bus info: cpu@0
          size: 700MHz
          capacity: 700MHz
          capabilities: cpufreq
  *-network
       description: Ethernet interface
       physical id: 1
       logical name: eth0
       serial: b8:27:XX:XX:XX:XX
       size: 100Mbit/s
       capacity: 100Mbit/s
       capabilities: ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd
       autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=smsc95xx
       driverversion=22-Aug-2005 duplex=full firmware=smsc95xx USB 2.0
       Ethernet ip=192.0.2.42 link=yes multicast=yes port=MII speed=100Mbit/s

Playing videos

In order to play videos at a decent framerate (using the hardware acceleration provided by the GPU), a custom version of mpv and some other software needs to be installed. Instructions are available at https://www.raspberrypi.org/forums/viewtopic.php?t=199775