Raspberry Pi Quick Install Guide
Installing Gentoo onto a Raspberry Pi is relatively straight forward and in some ways easier because a kernel image is provided by the Raspberry Pi Foundation. This means you can get Gentoo installed quickly onto you Raspberry Pi.
Contents |
Preparing the SD Card
The Raspberry Pi boots off a FAT32 /boot partition, you will also require a root and swap partition.
Create the Partitions
Use the fdisk command to create the partitions.
root # fdisk /dev/mmcblk0
Disk /dev/mmcblk0: 7948 MB, 7948206080 bytes
4 heads, 16 sectors/track, 242560 cylinders
Units = cylinders of 64 * 512 = 32768 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000635b7
Device Boot Start End Blocks Id System
/dev/mmcblk0p1 1 3201 102424 c W95 FAT32 (LBA)
/dev/mmcblk0p2 3202 7298 131104 82 Linux swap / Solaris
/dev/mmcblk0p3 7299 242560 7528384 83 Linux
Create the File Systems
root # mkfs.vfat -F 16 /dev/mmcblk0p1
root # mkswap /dev/mmcblk0p2
root # mkfs.ext4 /dev/mmcblk0p3Installing onto the SD card
Mounting the partitions
root # mkdir /mnt/gentoo
root # mount /dev/mmcblk0p3 /mnt/gentoo
root # mkdir /mnt/gentoo/boot/
root # mount /dev/mmcblk0p1 /mnt/gentoo/bootExtract Stage 3 Image
root # cd /tmp/
root # wget ftp://de-mirror.org/gentoo/releases/arm/autobuilds/current-stage3-armv6j_hardfp/stage3-armv6j_hardfp-*.tar.bz2
root # tar xfpj stage3-armv6j_hardfp-*.tar.bz2 -C /mnt/gentoo/Install Portage
root # wget http://distfiles.gentoo.org/snapshots/portage-latest.tar.bz2
root # tar xjf portage-latest.tar.bz2 -C /mnt/gentoo/usrInstall kernel and modules
The Raspberry Pi Foundation maintain a branch of the Linux kernel that will run on the Raspberry Pi, including a compiled version which we use here.
root # cd /tmp/
root # git clone --depth 1 git://github.com/raspberrypi/firmware/
root # cd firmware/boot
root # cp * /mnt/gentoo/boot/
root # cp -r ../modules /mnt/gentoo/lib/Configure the system
Edit fstab
Edit the fstab to match your partition scheme.
root # nano /mnt/gentoo/etc/fstab/dev/mmcblk0p1 /boot auto noauto,noatime 1 2 /dev/mmcblk0p3 / ext4 noatime 0 1 /dev/mmcblk0p2 none swap sw 0 0
Set boot options
You need to create a file cmdline.txt in /boot to pass options to the kernel.
root # nano /mnt/gentoo/boot/cmdline.txtdwc_otg.lpm_enable=0 console=ttyAMA0,115200 kgdboc=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p3 rootfstype=ext4 elevator=deadline rootwait
Edit make.conf
The default make.conf includes basic CFLAGS. If you would like to change the settings to something more 'optimal' for the Pi look at the details on the relevant wiki page.
Configure time zone
Find your time zone using this command.
root # ls /mnt/gentoo/usr/share/zoneinfo(Suppose you want to use Europe/London)
root # cp /mnt/gentoo/usr/share/zoneinfo/Europe/London /mnt/gentoo/etc/localtime(Next set the timezone)
root # echo "Europe/London" > /mnt/gentoo/etc/timezoneClear root password
As we do not chroot before we boot, you will need to unset the root password. Allowing you to login with a blank password for the root user.
root # nano /mnt/gentoo/etc/shadowEdit the line for root so it looks like the example below.
root::10770:0:::::
Unmount SD and then boot your Raspberry Pi
Unmount the SD card.
root # umount /mnt/gentoo/boot
root # umount /mnt/gentooPlugin the SD card to your Raspberry Pi, make sure you have a keyboard and monitor also plugged in then connect the power. Hopefully Gentoo will boot giving you a login prompt, login as root and no password. During the first boot you will see a few warnings and errors which we will fix in the next section.
Post boot configuration
Set root password
Immediately set a root password.
root # passwdEnabling networking on boot
Assuming you are using DHCP on the eth0.
root # cd /etc/init.d/
root # ln -s net.lo net.eth0
root # rc-config start net.eth0
root # rc-update add net.eth0 bootSelect profile
List the available profiles.
root # eselect profile listSelect the desired profile, for example [25] default/linux/arm/13.0/armv6j:
root # eselect profile set 25Configuring inittab and rc.conf
Uncomment the linux specific rc.conf rc_sys value, to stop warning in boot up.
root # nano /etc/rc.confrc_sys=""
Comment out the s0 Serial console to stop "INIT: Id "s0" respawning too fast" messages on the console.
root # nano /etc/inittab# SERIAL CONSOLES #s0:12345:respawn:/sbin/agetty 9600 ttyS0 vt100 #s1:12345:respawn:/sbin/agetty 9600 ttyS1 vt100
Enable software clock
The Raspberry Pi does not have a hardware clock, so you need to disable the hwclock daemon and enable swclock.
root # rc-update add swclock boot
root # rc-update del hwclock bootYou still need to set the date before to install any package or in compiling fase it will complain. Check system time using date command.
root # date
Thu May 02 04:21:18 UTC 2013
If the date/time displayed is wrong, update it using the date MMDDhhmmYYYY syntax (Month, Day, hour, minute and Year). At this stage, you should start use the timezone you setted before in the Configure time zone section. For instance, to set the date to May 02th, 04:21 in the year 2013:
root # date 050204212013Now you can set the system time using NTP software to setup the system clock on boot.
root # emerge --ask ntproot # rc-update add ntp-client defaultEnable SSH Daemon
root # rc-update add sshd default
root # /etc/init.d/sshd startOverclocking
It is very easy to overclock a Raspberry Pi up to 1000MHz without affecting your warranty [1]
#“None” “700MHz ARM, 250MHz core, 400MHz SDRAM, 0 overvolt” #“Modest” “800MHz ARM, 300MHz core, 400MHz SDRAM, 0 overvolt” #"Medium” “900MHz ARM, 333MHz core, 450MHz SDRAM, 2 overvolt” #“High” “950MHz ARM, 450MHz core, 450MHz SDRAM, 6 overvolt” #“Turbo” “1000MHz ARM, 500MHz core, 500MHz SDRAM, 6 overvolt”
Enabling Overclocking
To enable overclocking select one of the suggest modes from the list above, "Medium" is generally a good starting point. Edit the /boot/config.txt, add the appropriate values and reboot the Raspberry Pi for changes to take effect.
root # mount /boot/
root # nano /boot/config.txtarm_freq=900 core_freq=333 sdram_freq=450 over_voltage=2
Optional cpufrequtils
To manage the CPU frequency scaling you can use the cpufrequtils.
root # emerge --ask cpufrequtilsroot # rc-update add cpufrequtils defaultThe default scaling governor can be changed in the /etc/conf.d/cpufrequtils file
START_OPTS="--governor ondemand" STOP_OPTS="--governor performance"
Confirm the current scaling and CPU using the cpufreq-info command
root # cpufreq-info
Force Turbo Option
The force turbo option turns off the dynamic clocks and runs the Raspberry Pi constantly at the highest arm_freq. [2] Edit the /boot/config.txt, add force_turbo=1 then reboot the Raspberry Pi for changes to take effect.
root # nano /boot/config.txtarm_freq=900 core_freq=333 sdram_freq=450 over_voltage=2 force_turbo=1
Changing memory split
Not strictly speaking speaking overclocking, but the memory used by the GPU can be changed. To change the memory used by the GPU down to a minimum of 16MB add the gpu_mem value to /boot/config.txt, then reboot the Raspberry Pi for changes to take effect.
gpu_mem=16
Cross building (Optional)
This is not strictly required, but it is extremely practical given the source driven nature of Gentoo. Building almost anything on the Raspberry Pi takes a very, very long time - especially when there are a lot of dependencies involved.
Fortunately, you can offload much of the heavy lifting work to a more powerful system (such as your main gentoo desktop/server) using crossdev and distcc (though this will only work for packages must compile c/c++).
Full details of using distcc and crossdev on the Raspberry Pi are described in Raspberry Pi Cross building.
Install Video Core Userland tools and libraries
The ARM side libraries for interfacing to Raspberry Pi GPU are included in a package raspberrypi-userland. Which includes the Video Core tools, GLES2, EGL, openmax and openVG libs that support the Raspberry Pi GPU.
root # emerge --ask raspberrypi-userlandSee also
External resources
- Gentoo Embedded Handbook with more information about embedded hardware, cross compiling and other related topics.
- Raspberry Pi Hub at eLinux wiki, with more advanced tutorials to get the most out of your Raspberry Pi
