Funtoo Linux Installation on ARM

Funtoo now provides stage3 images for arm platform. At this time armv5te, armv6j_hardfp and armv7a_hardfp stages available. If you would like us to support other processors (see the list below), please fill a bug report on [1].

List of ARM processor "flavors"

• armv4l-unknown-linux-gnu (Rebel NetWinder, HP Armada and other devices having an ARMv4 processor, which is only capable of running the old ABI. Nevertheless it should work on newer CPUs)
• armv4tl-softfloat-linux-gnueabi (OpenMoko FreeRunner and other devices using an ARMv4T processor. Uses the new ARM EABI and software floating point by default)
• armv5tel-softfloat-linux-gnueabi (almost all ARM NAS, devices based on the Marvell Orion and Marvell Kirkwood, Marvell Sheevaplug, Marvell OpenRD, Guruplug, Dreamplug, QNAP TS109/TS209/TS409/TS119/TS219/TS419, Buffalo Linkstation/Kurobox PRO, HP mv2120, HP iPAQ, Linksys NSLU2 and other devices using an ARMv5TE processor. Uses the new ARM EABI and software floating point by default)
• armv6j-unknown-linux-gnueabi (Raspberry Pi, Nokia N800/N810, Smart Q7, OMAP2-based devices and other multimedia devices using an ARMv6 CPU and VFP. Uses the new ARM EABI and hardware floating point by default)
• armv7a-unknown-linux-gnueabi (OMAP3-based devices(Beagleboard, IGEPv2, Devkit8000, AlwaysInnovating Touchbook, Nokia N900), OMAP4-based devices(Pandaboard), Freescale i.MX515-based devices(Efika MX, Babbage Board, Lange Board…) Marvell Dove/Armada, Nvidia Tegra2-based devices(Toshiba AC100, Toshiba Folio), ST-Ericsson NOVA A9500-based devices(Snowball), Exynos 4412 (Odroid-X, Odroid-Q, ODROID U2) and other devices using an ARMv7-A processor. Uses the new ARM EABI and generic(not NEON) hardware floating point by default
• armv7a-hardfloat-linux-gnueabi (Raspberry Pi 2. The same as armv7a-unknown-linux-gnueabi, but this one uses hardfloat instead of softfp. Read more about it here: http://wiki.debian.org/ArmHardFloatPort)

Default installation of Funtoo on your platform/board

This document is not a complete installation tutorial. Basic information about Funtoo Linux installation can be found on Funtoo Linux Installation. The goal of this document is to provide general information about installing Funtoo Linux on an ARM device, and highlight differences with a x86 installation.

The following notes are non-board specific. Other instructions can be found in the specific articles for the above mentioned devices.

Overview

Most of the ARM boards come with a SD card slot, so you will need an empty SD card (4GB is enough to get you started), in most cases the boards are also equipped with debug port which can be used with USB-to-serial cables, if you have one, you can use it to login to the machine without the need of connecting keyboards or displays. You will need a network connection to be able to download stages, kernel and update your portage tree.

Kernel and bootloader setup

Before you start you will need a kernel and a bootloader for your device. Some of the devices look for bootloader (in most cases U-Boot) on the SD along with the kernel.

More information about the kernel and bootloader can be found on pages specific for your device.

Installing Funtoo (overview)

The installation on these devices differs from the normal installation procedure of booting an installation environment and chrooting from there to your new root, and can be little bit easier, but in some cases tricky.

Overview of the installation:

• Extract stage3 to the 2nd partition of the SD card
• Extract portage snapshot
• Setup fstab
• Setup root password
• Configure hostname and networking (optional, but recommended)
• Enable SSH access (optional, but recommended)
• Enable serial console access (optional, but recommended)
• Correct RTC "bug" with swclock

Installing the Stage 3 tarball

ARM stage3 tarballs can be found on [2]. Use the subarchitecture that suits best your device.

Mount the partition that will hold your rootfs of the SD card and extract the stage3 you have downloaded.

root # mkdir /mnt/SD_root
root # mount /dev/sdcard-device-px /mnt/SD_root

Extract the stage3 (it may take a while).

root # tar xapf stage3-armv7a_hardfp-xxxx.tar.xz -C /mnt/SD_root

Extracting a portage snapshot

Now, download the portage snapshot from [3], and extract it to your partition.

root # tar xapf portage-latest.tar.xz -C /mnt/SD_root/usr

Setup fstab

Edit the /mnt/SD_root/etc/fstab file to look like this:

 /dev/mmcblk0p1		/boot		vfat		noauto,noatime	1 2
 /dev/mmcblk0p2		/		ext4		noatime		0 1

Adjust the partition devices and types to suit your needs.

Setting the default root password

   Warning

Don't skip this step. This part differs from the standard installation procedure, as the root password must be set outside of a chroot environment. Skipping this step will result in an impossibility to login.

Normally, for setting the password, one has to be able to run passwd. However that's not possible in this case since an x86 system can't run ARM binaries. Therefore, it is needed to modify the file that contains the passwords (/etc/shadow) to set a default root password.

Clearing the root password

This will allow to login with a blank password for the root user.

root # nano -w /mnt/SD_root/etc/shadow

Modify the line beginning by "root" to match the following:

root::10770:0:::::

   Warning

After initial login, remember to change the root password using the passwd command.

This didn't work for me. I hit enter at the password prompt, it gave me 3 tries, that was it. I solved the problem by adding my public key to /root/.ssh/authorized_keys (had to be created). Then I was accepted by public key authentication.

Choosing a root password (alternative)

First, generate a password. The output of this command will be used to modify the shadow file.

root # openssl passwd -1
or
root # python -c "import crypt, getpass, pwd; print crypt.crypt('password', '\$6\$SALTsalt\$')"

Then, edit the shadow file and use the output of the last command to replace "YOUR_PASSWORD_MD5".

root # nano -w /mnt/SD_root/etc/shadow

 root:YOUR_PASSWORD_MD5:14698:0:::::

Setup hostname and networking

Please read the Funtoo Linux Networking to configure your network.

Using swclock

One of the problems some of the devices have, is that they don't have a battery to save the clock time. To mitigate this, on Funtoo we have an option in our init system called swclock which sets the date of the system upon boot from a last modified date of a file.

First, add swclock to the boot runlevel.

root # ln -sf /etc/init.d/swclock /mnt/SD_root/etc/runlevels/boot

Then, remove hwclock from the startup because it sets the date from the RTC, which is 2000-01-01 upon startup and overrides swclock's date.

root # rm /mnt/SD_root/etc/runlevels/boot/hwclock

swclock uses the /lib/rc/cache/shutdowntime modification time to set the date, therefore we update it to have the current date and time.

root # touch /mnt/SD_root/lib/rc/cache/shutdowntime

Although this doesn't fix the issue, at least helps to set a sane date and time. Note: Consider using NTP, documented on the next chapter

Enabling SSH access (optional)

Adding sshd to the default runlevel will enable access to the device using ssh (if network has been configured).

root # ln -sf /etc/init.d/sshd /mnt/SD_root/etc/runlevels/default

If no network has been configured yet, it might be a good idea to add dhcpcd in the default runlevel as well.

root # ln -sf /etc/init.d/dhcpcd /mnt/SD_root/etc/runlevels/default

Enabling serial console access (optional)

By default the ttyS0 port is configured at 9600 bps. However, almost all of the ARM devices run the serial port at 115200 bps. Also, the port device names differ (ttyO2 for Pandaboard, ttySAC1 for Odroid-X ...). So edit your /etc/inittab file:

root # nano -w /mnt/SD_root/etc/inittab

Example for Pandaboard:

s0:12345:respawn:/sbin/agetty 115200 ttyO2 vt100

Finishing the installation and booting up the new system

Let's unmount the SD card.

root # umount /mnt/SD_root

Troubleshooting

With the armv5te at least, these instructions work great. However, when it is time to update sys-devel/gcc this underpowered wimp has trouble, mainly due to limited memory I think. Cross-compiling toolchains made by crossdev work well within limits, it won't do gcc. However I have found a trick that works well and solves this, thanks to the timely posting of new stage3's by Funtoo.
Simply make a chroot using qemu-user files as described here: http://wiki.gentoo.org/wiki/Cross_Container_Support_Project Enter the chroot and tweak your /etc/portage/make.conf to point to the directory you wish to save packages to (PACKAGEDIR) and any other necessary tweaks in there.
Since this latest stage3 will have the latest gcc installed in it, simply enter:

root # quickpkg sys-devel/gcc

It will build the binary package, which then installs on my Dockstar quickly & easily in comparison to compiling 48 hours and then failing.
As an added bonus you now have a nifty arm chroot you may find handy for other tasks.