Setup a Cross-Compile Environment for Drobo

The first step in cross-compiling software is to get a working environment that you can use for it. I am setting up my environment to cross compile for the Drobo FS using the latest Ubuntu Lucid and used this article Building MediaTomb for the Drobo using Ubunutu to get my system working and to create this guide.

First, I setup an Ubuntu 10.04 installation within a VM image as I tend to change computers and laptops frequently and would like to keep this image for Drobo FS development. As in the noted article, everything will be done within a chroot environment and then copied to the Drobo FS.

# install schroot and debootstrap

sudo apt-get install schroot debootstrap

# create new root

sudo mkdir -p /var/chroot/drobofs

# create /etc/schroot/chroot.d/drobofs

cat << END_OF_DROBOFS > /etc/schroot/chroot.d/drobofs
[drobofs]
description=Ubunutu Intrepid for DroboApps on Drobo FS
location=/var/chroot/drobofs
priority=3
users=<Your Username>
groups=<Your Group>
root-groups=root
run-setup-scripts=true
run-exec-scripts=true
END_OF_DROBOFS

# create system in chroot jail

sudo debootstrap --variant=buildd --arch i386 intrepid /var/chroot/drobofs

# download the toolchain

• Drobo FS - http://www.codesourcery.com/gnu_toolchains/arm/releases/2007q1-21
• Or directly from - arm-2007q1-21-arm-none-linux-gnueabi-i686-pc-linux-gnu.tar.bz2
• DroboShare - http://www.codesourcery.com/gnu_toolchains/arm/releases/2006q1-6
• Or directly from - arm-2006q1-6-arm-none-linux-gnueabi-i686-pc-linux-gnu.tar.bz2

# extract the toolchain

cd /var/chroot/drobofs/usr/local
 
# DroboShare
sudo tar -xjf arm-2006q1-6-arm-none-linux-gnueabi-i686-pc-linux-gnu.tar.bz2
 
# Drobo FS
sudo tar -xjf arm-2007q1-21-arm-none-linux-gnueabi-i686-pc-linux-gnu.tar.bz2
 
## the resulting toolchain is put into a /usr/local/arm-xxx directory
## must either move the files to the parent or put them in the path setting

# copy resolv.conf into the chroot environment

sudo cp /etc/resolv.conf /var/chroot/drobofs/etc/resolv.conf

# Optional: if run_setup_scripts is not used for chroot, Mount the required filesystems

sudo mount -o bind /proc /var/chroot/drobofs/proc

# Activate the chroot to complete setup

sudo schroot -c drobofs -d /root

# Load some extra packages

apt-get install vim
apt-get install wget
apt-get install automake autoconf libtool autotools-dev m4

# type exit to leave the chroot

exit

When cross-compiling, you want to use the system's binaries for running development tools but make the compiler and linker using the ARM headers, libraries, and binaries.

From the Drobo FS SDK 1.0:

• The Drobo FS platform is an ARM core with a Linux OS (Marvell-Linux)
• The Drobo FS CPU uses an ARM926ej-s core architecture and an ARMv5te instruction set architecture.
• add either '–host=arm-none-linux-gnueabi' switch or '–cross-compile –cross-prefix=arm-none-linux-gnueabi-' idiom during configure.

The following steps can be used to create an application build environment or depending on your needs, you can change the build folders as desired when building multiple applications or targets.

# create a directory for code (or use the specific application name)

sudo mkdir -p /var/chroot/drobofs/home/build

# create a directory for resulting binaries (or use a specific application name)

sudo mkdir -p /var/chroot/drobofs/usr/arm

# Activate the chroot to build application

sudo schroot -c drobofs -d /root

The following environment variables will help with building to a non-standard directory:

export CFLAGS="-I/usr/arm/include -march=armv5te"
export CPPFLAGS=${CFLAGS}
export LDFLAGS="-L/usr/arm/lib"
export CC=arm-none-linux-gnueabi-gcc
# replace /usr/arm as needed to match your build output path