Compiling Angstrom Linux Distribution

Compiling Linux

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Overview

The Atlas-SoC board ships with a precompiled Angstrom 1.7 image. The atlas-soc-image includes a number of example designs and utilities to aid in the testing and development of Altera SoC devices. These include a pre-installed toolchain, example drivers and applications, as well as an XFCE Desktop environment served over VNC.

Documentation for Angstrom can be found here http://angstrom-distribution.org/

The build process uses some custom Yocto/Angstrom meta layers, these are:

meta-altera : Fork of Altera's meta layer meta-altera-refdes : Fork of Altera's meta-refdes layer with Atlas SoC specific recipes atlas-soc-fftsw-apps : Example userspace application for FFT atlas-soc-webcontent : Atlas SoC Webcontent for board hosted website

Please note that these will be fetched as part of the normal build process.

Prerequisites

The following items are required:

1. Access to github
2. A Linux host (Fedora 21/22 have been tested, but Ubuntu, and Centos 6/7
3. Configuration / package install of host system per http://www.yoctoproject.org/docs/1.7.2/yocto-project-qs/yocto-project-qs.html

Procedure

The Angstrom build is entirely scripted in a bash script included with the Hardware design. Although it is not required to compile the Hardware design, please follow the steps download and extract it per Compiling Hardware Design and Preloader. There is no need to run the 6th or 7th steps.

The script is located in the scripts directory, it will download all of the relevant git repositories, setup the environment, and bitbake the atlas-soc-image.

Steps to build:

1. ) In a bash terminal, create a directory with a shorter hierarchy ( I use /data/atlas/ ) as Yocto/Angstrom appears not to tolerate long path names
2. ) source the build script

   * mkdir -p /data/atlas
   * source <Path to Atlas SoC Hardware design>/atlas-soc-ghrd/scripts/atlas_socdk_setup_angstrom_1.7.sh

The build process takes approximately 1 1/2 hours on a quad core I7 with 16GB of ram.

Results

The results of the build we are interested in will be located in setup-scripts/deploy/glibc/images/atlas_sockit. We are interested in the following files:

zImage → Kernel zImage

zImage-socfpga_cyclone5_de0_sockit.dtb → Devicetree binary for the Atlas SoC board

atlas-soc-image-atlas_sockit.ext3 → Root filesystem

Notes on the build script

The build script below will not be maintained, but notes explain the various steps.

#!/bin/bash

# Clone 1.7 angstrom repo 
git clone -b angstrom-v2014.12-yocto1.7 git://github.com/Angstrom-distribution/setup-scripts.git

# Add sources meta-layer sources to layers.txt.  layers.txt is used by the oebb.sh script to list all of the layers needing to be fetched
echo "meta-altera,git://github.com/dwesterg/meta-altera.git,angstrom-v2014.12-yocto1.7,HEAD" >> setup-scripts/sources/layers.txt
echo "meta-altera-refdes,git://github.com/dwesterg/meta-altera-refdes.git,angstrom-v2014.12-yocto1.7,HEAD" >> setup-scripts/sources/layers.txt

# add BBLayers to conf/bblayers.conf.  This ensures that bitbake will parse these new layers
sed -i '/meta-96boards/a \ \ \$\{TOPDIR\}\/sources\/meta-altera-refdes \\' setup-scripts/conf/bblayers.conf
sed -i '/meta-96boards/a \ \ \$\{TOPDIR\}\/sources\/meta-altera \\' setup-scripts/conf/bblayers.conf

# disable kde4 repo.  gitorious repo is gone, this layer isn't used so just disable it.
sed -i '/meta-kde4/d' setup-scripts/sources/layers.txt
sed -i '/meta-kde4/d' setup-scripts/conf/bblayers.conf

# gumstix on gitorious too
sed -i '/meta-gumstix-community/d' setup-scripts/sources/layers.txt
sed -i '/meta-gumstix-community/d' setup-scripts/conf/bblayers.conf

# This disabled the removal of work done suring the build.  It increases the disk usage , but all of the intermediary build source will be available for debugging the build if required
sed -i '/rm_work/d' setup-scripts/conf/local.conf

# This sets up the build for the correct machine per Yocto/Angstrom norms
pushd setup-scripts
MACHINE=atlas_sockit ./oebb.sh config atlas_sockit
popd

# Change download and cache dirs.  I like to do this so that the downloads and cache can be used for later/other builds.
sed -i '/DL_DIR/d' setup-scripts/conf/site.conf
sed -i '/SSTATE_DIR/d' setup-scripts/conf/site.conf
echo "DL_DIR = \"\${TOPDIR}/../downloads\"" >> setup-scripts/conf/site.conf
echo "SSTATE_DIR = \"\${TOPDIR}/../ang_sstate_cache\"" >> setup-scripts/conf/site.conf

# source the environment script
cd setup-scripts
source environment-angstrom-v2014.12

# We want to build the current mainline kernel supported by meta-altera, not the LTSI kernel, so export this variable
export KERNEL_PROVIDER="linux-altera"
export BB_ENV_EXTRAWHITE="${BB_ENV_EXTRAWHITE} KERNEL_PROVIDER"

# Build the image
bitbake atlas-soc-image