[gentoo-embedded] x86 SBC Gentoo Embedded HowTo version 0.06 (almost finished)

[Heath H Holcomb]

Version 0.06
Please add, delete, modify. Thanks!
This procedure produces a working embedded rootfs, that boots form a hard 
drive on a Geode based SBC (single board computer); at least on my 
development system.

I've update my website with this version also.
http://www.bulah.com/embeddedgentoo.html


#--------------------------------------------------------------------------------
# Embedded Gentoo How-To for x86
#
# A how-to guide to setup a Gentoo embedded environment, you must be root.
# These commands are to be run on your development system, 
# any x86 Gentoo Linux computer will do.  The system should be fast,
# to speed development.  The target can be any x86 based SBC.  I'm
# using a Geode based SBC.  Latter I'll use a Via based SBC.
#
# version 0.06
# 2005.6.6
#
# Heath Holcomb (heath at bulah.com)
# Ned Ludd (embedded Gentoo project lead, original commands posted)
# Lloyd Sargent (contributor)
# Yuri Vasilevshi (contributor)
# Mike George (contributor)
# Kammi Cazze (contributor)
# Marius Schaefer (contributor)
#
# Definitions and Terms
# system_rootfs = your regular rootfs
# development_rootfs = what you use to build the embedded_rootfs
# embedded_rootfs = rootfs you deploy to the target system
# SBC = single board computer (here it's an x86 based)
#
# References
# http://www.gentoo.org/doc/en/handbook/index.xml
# http://www.epiawiki.org
# http://epia.kalf.org
# Gentoo embedded mailing list (gentoo-embedded@l.g.o)
#
#
# Overview of process (steps)
# 1 - Prepare the development_rootfs from your system_rootfs
# 2 - Build the development_rootfs
# 3 - Build the embedded_rootfs
# 4 - Build and install non-system programs to the embedded_rootfs
# 5 - Build and install a kernel to the embedded_rootfs
# 6 - Deploy embedded_rootfs to target
#
#--------------------------------------------------------------------------------

#----- Step 1 - Prepare the development_rootfs from your system_rootfs -------

# You must be root.
su -

# Create the development_rootfs.
# I use i586 because of target is a Geode processor.
mkdir -p /opt/i586-gentoo-uclibc-linux/usr/portage

# Download the latest stage 1 tarball.
wget \ 
http://gentoo.osuosl.org/experimental/x86/embedded/stages/stage1-x86-uclibc-2005.0.tar.bz2

# Untar the stage to the development_rootfs.
tar -xvjf stage1-x86-uclibc-2005.0.tar.bz2 -C /opt/i586-gentoo-uclibc-linux/

# Mount the proc and portage directories to your development_rootfs.
# Makes your system_rootfs's proc and portage directory available from inside
# of your development_rootfs (after chrooting).
mount --bind /proc /opt/i586-gentoo-uclibc-linux/proc/
mount --bind /usr/portage /opt/i586-gentoo-uclibc-linux/usr/portage

# Copy over DNS information to the development_rootfs.
cp /etc/resolv.conf /opt/i586-gentoo-uclibc-linux/etc/resolv.conf

# Chroot into the development_rootfs.
chroot /opt/i586-gentoo-uclibc-linux /bin/bash --login


#----- Step 2 - Build the development_rootfs ---------------------------------

# Create new environment and load variables into memory.
env-update
source /etc/profile

# Modify make.conf file to your liking/needs.
nano -w /etc/make.conf
# This is for my target, Geode x86 processor.
/*
USE="bitmap-fonts minimal truetype-fonts uclibc mmx"
CHOST="i586-gentoo-linux-uclibc"
CFLAGS="-march=i586 -Os -pipe -fomit-frame-pointer -mmmx"
CXXFLAGS="${CFLAGS}"
FEATURES="buildpkg"

VIDEO_CARDS="chips"
UCLIBC_CPU="586MMX"
*/

# Set profile to use 2.6 kernel.
# The current stage uses 2.4 by default, and for most cases you are going
# to want a 2.6.x kernel.
rm /etc/make.profile
ln -s /usr/portage/profiles/uclibc/x86 /etc/make.profile

# Start the bootstrap script.
cd /usr/portage/scripts
./bootstrap.sh -p -v
./bootstrap.sh

# Workaround 1
# Failure compiling uclibc (gcc-config error: Could not run/locate "gcc")?
# If you get a failure while bootstrap is compileing uclibc here are the steps
# to work around the problem.
gcc-config 1
source /etc/profile
./bootstrap.sh

# Emerge the system ebuild for the development_rootfs.
emerge -e system

# Workaround 2
# During emerge -e system, python-fchksum failes complaing about
# gcc-config error: Could not run/locate "i386-gentoo-linux-uclibc-gcc"
# The following commands work around this problem.
emerge python
emerge -e system


#----- Step 3 - Build the embedded_rootfs ------------------------------------

# Create the embedded_rootfs directory.
mkdir /embedded_rootfs

# Emerge baselayout-lite into embedded_rootfs.
# This gives your system a basic file structure.
# 1.0_pre1 is the only one that is stable, right?
cd /usr/portage/sys-apps/baselayout-lite/
ROOT=/embedded_rootfs emerge baselayout-lite-1.0_pre1.ebuild

# Workaround 3
# Baselayout-lite is still beta, so a few fixes are needed.
# There needs to be a directory "log" in /var.
# Inittab calls for /usr/bin/tail, but it needs to /usr/bin.
mkdir /embedded_rootfs/var/log
nano -w /embedded_rootfs/etc/inittab
/*
#tty3::respawn:/usr/bin/tail -f /var/log/messages
tty3::respawn:/bin/tail -f /var/log/messages
*/

# Emerge uclibc into the embedded_rootfs.
# Use the -K option because we don't get the extra files created by the
# build/emerge process into our embedded rootfs which needs to be as 
# small as possible.
ROOT=/embedded_rootfs emerge -K uclibc

# Emerge busybox into the embedded_rootfs.
# First you must emerge it into your development_rootfs.
# This does not create the symlinks in our development embedded rootfs.
emerge busybox
ROOT=/embedded_rootfs emerge -K busybox

# Create the symlinks for busybox in the embedded_rootfs.
mkdir /embedded_rootfs/proc
mount -o bind /proc/ /embedded_rootfs/proc/
chroot /embedded_rootfs /bin/busybox --install -s
umount /embedded_rootfs/proc

# Set time zone in your embedded_rootfs.
# See http://leaf.sourceforge.net/doc/guide/buci-tz.html for details.
# For central standard time in the US, use "CST6CDT".
nano -w /embedded_rootfs/etc/TZ
/*
CST6CDT
*/

# Install a boot loader (usually grug or lilo).
# Once you copy/deploy your embedded_rootfs program to you target SBC you will 
# have to run the grub on the command line to write to the master boot record
# (MBR).
# Ncurses is needed by grub, if you are not using gurb then you don't need 
# ncurses. For some reason not all of /boot/grub is copied over to the 
# embedded_rootfs, so a extra manual copy step is needed.
ROOT=/embedded_rootfs emerge -K ncurses
emerge grub
ROOT=/embedded_rootfs emerge -K grub
cp -R /boot/grub /embedded_rootfs/boot/

# Modify your boot configure file.
# The example below is for a gurb, for a boot partition on /dev/hda1 and only
# one partition on the target SBC system.
nano -w /embedded_rootfs/boot/grub/grub.conf
/*
default 0
timeout 10
splashimage=(hd0,0)/boot/grub/splash.xpm.gz

title=Linux 2.6.x
root (hd0,0)
kernel /vmlinuz-2.6.x root=/dev/hda1 vga=792
*/

# Set root password
ROOT=/embedded_rootfs passwd

# Modify fstab.
# Below is mine, yours may vary.
nano -w /embedded_rootfs/etc/fstab
/*
/dev/hda1		/		reiserfs	defaults	0 0
none			/proc		proc		defaults  	0 0
none			/sys		sysfs		defaults	0 0
none			/dev/shm	tmpfs	defaults	0 0
*/

#---- Step 4 - Build and install non-system programs to the embedded_rootfs --

# Emerge other software you need for you embedded target.
# This is very wildly depending on your needs.
# Also your proprietary application will be done here.
emerge foobar*
ROOT=/embedded_rootfs emerge -K foobar*


#---- Step 5 - Build and install a kernel to the embedded_rootfs -------------

# Install a kernel into embedded_rootfs.
# First we will emerge it into our development_rootfs, then configure and 
# build it.
emerge vanilla-sources
cd /usr/src/
cd linux
make menuconfig
# configure your kernel for your TARGET SBC here
make
ROOT=/embedded_rootfs make modules_install
cp /usr/src/linux/arch/i386/boot/bzImage /embedded_rootfs/boot/vmlinuz-2.6.x

# A few notes on compiling your kernel.
# If deploying to Compact Flash/DiskOnChip/SD us ext2, as the journaling
# filing systems "write" to much for a flash device.
# If deploying to a hard drive use a journaling filing system, such as
# ext3 or reiserfs.


#---- Step 6 - Deploy embedded_rootfs to target ------------------------------

# Prepare a Gentoo (or any Linux distro) system on the target SBC using a
# harddrive.  This is known as the target development rootfs.
# We will create a partition (/embedded_rootfs) that will server as our 
# "test" partition to deploy our embedded_rootfs that we generate on our
# development_system.
#
# I use the following partitions to speed development (yours may vary):
# /dev/hda1 - /embedded_rootfs - 1 GB
# /dev/hda2 - /boot - 100 MB
# /dev/hda3 - swap - (size varies, 512 MB is a good number)
# /dev/hda4 - / - (what is left, at least 1.5 GB per 2005.0 install guide 
specs)
#
# Copy over your embedded_rootfs from you development system to your target
# system and the directory /embedded_rootfs.  This needs to be done via NFS as
# need to preserve the permissions.
#
#The following commands are done from the
# target development rootfs.
mount -t reiserfs /dev/hda1 /mnt/embedded_rootfs
mount -t nfs 
192.168.0.10:/opt/i586-gentoo-uclibc-linux/embedded_rootfs /mnt/transfer
cp -adpR /mnt/transfer/* /mnt/embedded_rootfs


# Modify your target system's gurb.conf (or lilo.conf) for allow you to boot 
# to the embedded_rootfs partition.
#
# Reboot, and if all goes well you'll be greeted with a login prompt.
#
# Fin.



-- 
Heath Holcomb
liquidcable
liquidcable at bulah.com
-- 
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