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HOWTO_setup_gentoo_on_a_pda_or_embedded_system

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Contents

PDAs

Introduction

The goal of this HOWTO is to show a (quite experimental) way to install Gentoo/Embedded on a PDA, focused on the SHARP Zaurus SL-5x00, but probably easily adaptable to any other PDA out there, for which kernel and driver support exists. We will use uclibc instead of glibc, which should keep more RAM free for your applications.

Note: This is in development and there is still a long way to go.

There are not only good applications missing for embedded purposes, we currently have a hard time to get a X-Server up and running.
To make it clear, this IS NOT READY FOR USERS, but perhaps intersting for advanced users or developers, that might want to help us.

We are in really need of some who could help us getting an embedded and working X-server!

Steps Outline

This are the steps we want to go and they are basically the same for every PDA. Before you start doing this, make sure that you have the ability to boot into SD and over network. If you have no zaurus SL-5x00 we don't (yet) support your PDA. That means you will probably have to do some handwork, at least with the X-Server, but possible other stuff, too. If you want to make that work on our base here, contact us and help us to extend number of supported handhelds.

Prepare PC

Linux Kernel Configuration: Activate in kernel nfsd
File systems  ---> 
  Network File Systems  --->
    <*/M> NFS server support
    [*]     Provide NFSv3 server support

And setup userland:

emerge -av nfs-utils

add to /etc/exports (replacing 192.168.1.z by Zaurus' IP address):

File: /etc/exports
/exports/collie/devroot  192.168.1.z(async,rw,no_root_squash,no_all_squash)
/usr/portage	192.168.1.z(async,rw,no_root_squash,no_all_squash)

In /exports/collie/devroot we will unpack the stage-archive, it will be the root-directory of your building-environment. Place it whereever you like.

Code: [re]start nfs service
/etc/init.d/nfs [re]start

Prepare Z

For now we need the Zaurus to have Altboot[1] to boot to Gentoo once it's installed on NFS/SD/CF and the easiest way to get it is to install hentges' ROM [2] with the 64-0 kernel (we'll need all the RAM we can get to compile). But this is not needed now, you will need it when you want to boot into your gentoo.

It is also highly recommended to have a ssh daemon (openssh/dropbear) and GNU Screen installed on Zaurus. Easiest way is to install openzaurus from www.openzaurus.org, the non-graphical version are enough for our purposes. If you use another PDA than the zaurus, you must find the right distribution by yourself.

NFS Mount Working Area

Now we need to mount our work area where we will compile all the needed packages that will latter be installed on NFS/SD/CF.

Code: Mount NFS
mkdir /mnt/gentoo
mount -t nfs 192.168.1.pc:/exports/collie/devroot /mnt/gentoo -o nolock,hard,rw,rsize=8192,wsize=8192,noatime,async

The nolock-option is very important, without it portage will fail doing its job!

Setup build environment

First we need to download the latest arm softfloat uclibc stage (available at http://yvasilev.main.hsphere.com/zentoo/ [4]) and then unpack it:

# tar -xjpf /mnt/misc/gentoo/stages/stage3-arm-uclibc-softfloat-20050915.tar.bz2 -C /mnt/gentoo

In this example we used stage3 as other stages won't give us any extra advantage over it.

Then we mount some other partitions needed by build environment we care creating:

Code: Mount some other partitions
mkdir /mnt/gentoo/usr/portage
mount -t nfs 192.168.1.pc:/usr/portage /mnt/gentoo/usr/portage -o nolock,hard,rw,rsize=8192,wsize=8192,noatime,async
mount -o bind /dev /mnt/gentoo/dev
mount -t proc none /mnt/gentoo/proc

(You probably want to put the mounting-actions into a shell script, you will have to retype them at every restart of your PDA otherwise)

Copy dns server information so we can resolve domain names form withing the build env:

cp /etc/resolv.conf /mnt/gentoo/etc/resolv.conf

And Finally chroot into our build env:

Code: chroot
chroot /mnt/gentoo /bin/bash --login
env-update
source /etc/profile

Setup overlay & packages directories

The latest portage overlay for zentoo is available at [3]. Put into a good place in the zentoo-root.

configure portage

First we make sure /etc.make.profile points to 2.4 kernel profile, when you are using a 2.4 kernel (as they are still use on the SL-5x00).

# ls -l /etc/make.profile
lrwxrwxrwx  1 root root 38 Nov  9 07:54 /etc/make.profile -> ../usr/portage/profiles/uclibc/arm/2.4

If you are lucky and you run a working 2.6 kernel, let it point simply to ../usr/portage/profiles/uclibc/arm.

Then edit /etc/make.conf. The following would be a good set of USE-flags:

File: /etc/make.conf
USE="X aac apm avi bash-completion divx4linux fbcon fbdev ffmpeg flac \
     freetype gif gtk2 imlib2 jpeg libwww mad matroska minimal mpeg \
     ncurses nocxx oss pcmcia python qt readline truetype uclibc \
     win32codecs wxwindows vcd vorbis -perl -opengl -qt -fortran -berkdb"

We recommend using -Os and -fomit-frame-pointer as CFLAGS. Your -march settings depends on your PDA. For the SL-5000 and SL-5500 you should use -march=armv4, on XSCALES (as in the SL-5600) you can use -march=armv5te -mtune=xscale. You should set buildpkg in FEATURES, as your builds will be that damn slow, that you will be happy to have binary packages later.

You may add LDFLAGS="-Wl,-O1" to your make.conf and you should set UCLIBC_CPU, depending on your CPU. For xscales it should be UCLIBC_CPU="ARM_XSCALE".

You should set MAKEOPTS="-j1", too. Your PDA will have a hard time even with only one make running.

Add nocxx to the USE-flags, that way you work around a bug in uclibc-0.9.28 and keep the time for compiling gcc shorter. We don't support any C++ apps until now anyway.

To

File: /etc/portage/package.keywords
sys-libs/uclibc -*

With all this we unmask uClibc v0.9.28 and the parts of Modular X.Org we are going to use, make sure that we use the right versions of glib/gtk+ and add some extra categories into the list of the valid ones.

Finally we can run `emerge info` to verify some of the information we have just set.

update system

Now we finally can start using our build env for what it is. This means we start to merge stuff. Before you do that, you should make as much RAM free as possible. Make sure that there is no OPIE or GPE running (you can stop both via init.d scripts)and see, what else is running on your PDA. Kill everything you don't need.

Moreover you probably need swap, many builds will segfault with only 32 MB RAM (with 64 MB they might work). You have two possibilitys with their own advantages and disadvantages:

1. Mount swap via nfs:
Create an empty file in your zenntoo-root and make loop-device out of it on the zaurus. Then create a swap-filesystem in the loopback-device and activate it with swapon This way you can mount nearly as much RAM as you want without damaging anything. Disadvantage is, that this swap will be awfully slow. Moreover some builds will freeze might zaurus, when you build them with nfs-mounted swap. There are only a few packages which fail that way and this might be true only for 32 MB RAM systems. For this packages you have to switch to the second possibility.

2.Missuse a flash-card for swap:
Using a CF-card is quite simple. mkswap /dev/hda1 and swapon /dev/hda1 should be all you need in many cases. But flash cards have a limited write-cycle lifetime and as being a swap device, there will be much writing. So using a flash card as a swap-device, you will reduce it's lifetime. But perhaps you have an old flash-card, that you don't use anymore. An old 64 MB CF-card will do it's duty and is cheap to buy.

Make sure that you have the latest portage on your host-computer.

The stage is optimized for the armv4, if you have a more modern CPU, you may want to recompile your stage for making use of the better CPU: emerge -e world

Update the rest of the build env: emerge -uDav system

Test it, boot into it

Emerging into Final ROOT

Warning: THE REST OF THIS HOWTO IS NOT TESTED AND WILL NOT HELP YOU MUCH, AS THERE IS NO WORKING X-SERVER

To make installation a little bit easier (and make sure we don't forget any of the needed parampeters) we can set an alias to emerge program for when we want to emerge packages to the device.

alias zmerge="ROOT=/mnt/root emerge --usepkgonly"

Where /mnt/root can be an directory inside the nfs mount we are working in, in which case we will be able to nfs boot into it with altboot. Or it can be a bind mounted SD/CF card // FIXME: this needs pcmcia-cs package to be installed for wireless cards to work. //

// FIXME: This will be replaced by a PDA profile + zmerge -av system // And then we start emerging all the needed parts

zmerge -av baselayout util-linux gawk module-init-tools grep net-tools findutils procps coreutils kbd

At this stage it may complain that there is a package for witch there is no precompiled form, so emerge can't do it with the usepkgonly option. So we need to generate binary packages for all the packages and their dependencies we are going to use, this can be done with:

emerge -ebkav system
Code: Install libc
zmerge -av uclibc

Code: Install GUI
zmerge -av kdrive
zmerge -av gtk+
zmerge -av matchbox-common
zmerge -av gpe

try 2

zmerge -av portage
zmerge -av baselayout
zmerge -av uclibc
install -d /mnt/root/usr/local/portage
mount -o  bind /usr/local/portage/packages /mnt/root/usr/local/portage
chroot /mnt/root /bin/bash --login

Configure the Installation

Set the time zone (available values are in [5]): echo

Edit fstab

Copy /dev cd ${ROOT}/dev/ ; ./MAKEDEV generic


[1] http://hentges.net/misc/openzaurus/docs/altboot.shtml
[2] http://hentges.net/misc/openzaurus/index.shtml
[3] http://yvasilev.main.hsphere.com/zentoo/test/zoverlay-test.tar.bz2
[4] http://yvasilev.main.hsphere.com/zentoo/stages/

Contact us

This work is done by Yuri Vasilevski aka yvasilev and Björn Ruberg aka Jinidog. You can find us in #gentoo-embedded on freenode. Feel free to consult us, if you want to help out (we need helpers!) or have questions.

Routers and Modems

->new page for other embeded system

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Last modified: Mon, 03 Dec 2007 13:05:00 +0000 Hits: 19,051