Install bundled 32-bit system in 64-bit system

Install the Base 32-bit System

1. Create the directory:

mkdir /opt/arch32

2. Generate temporary pacman configuration files for chroot:

sed -e 's/\$arch/i686/g' /etc/pacman.d/mirrorlist > /opt/arch32/mirrorlist
sed -e 's@/etc/pacman.d/mirrorlist@/opt/arch32/mirrorlist@g' /etc/pacman.conf > /opt/arch32/pacman.conf

These files would conflict with the normal pacman files, which will be installed in the later steps. For this reason they must be put into a temporary location (/opt/arch32 is used here). Remember to delete/comment the multilib repo, if you have enable it, in the /opt/arch32/pacman.conf file

The --root switch in the pacman command below will create /var/log/pacman.log and /var/lib/pacman/db.lck inside /opt/arch32. The pacman log will be /opt/arch32/var/log/pacman.log and will not interfere with the native 64-bit installation. There is no need for a LogFile directive in /etc/pacman.conf or a --logfile switch.

The --cachedir switch is for the package to be cached in /opt/arch32/var/cache/pacman/pkg instead of /var/cache/pacman/pkg.

Use the --config switch to tell pacman to use the configuration file generated above, rather than /etc/pacman.conf.

3. Create the directory, just to be sure:

mkdir -p /opt/arch32/var/{cache/pacman/pkg,lib/pacman}

3b. Edit 'Architecture' for pacman >= 3.4

# In /opt/arch32/pacman.conf
# Architecture=auto
Architecture=i686

3c. Users following the Arch installer method will have a line at the top of /etc/pacman.d/mirrorlist similar to:

# Mirror used during installation
Server = http://mirror.rit.edu/archlinux/$repo/os/x86_64

The 'sed' command above searches for instances of '$arch' and replaces them with 'i686'. Unfortunately, since this installation mirror is explicitly set as x86_64, it is not replaced and will cause issues. Either comment it out or change it like so:

Server = http://mirror.rit.edu/archlinux/$repo/os/i686

4. Sync pacman:

pacman --root /opt/arch32 --cachedir /opt/arch32/var/cache/pacman/pkg --config /opt/arch32/pacman.conf -Sy

5. Install the base and optionally base-devel groups:

pacman --root /opt/arch32 --cachedir /opt/arch32/var/cache/pacman/pkg --config /opt/arch32/pacman.conf -S base base-devel

Note: For minimal arch32 chroot installation following packages are sufficient: bash, coreutils, filesystem, grep, gzip, licenses, sed, pacman and file.

Optionally remove the temporary pacman configuration files.

rm /opt/arch32/{mirrorlist,pacman.conf}

6. To use the newly installed pacman, uncomment some mirrors in /opt/arch32/etc/pacman.d/mirrorlist and make any other desired changes to the new pacman installation.

7. Edit your /opt/arch32/etc/pacman.conf and change that Architecture from auto back to i686.

Create an Arch32 Daemon Script and Systemd Service

/etc/systemd/system/arch32.service

[Unit]
Description=32-bit chroot

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/usr/local/bin/arch32 start
ExecStop=/usr/local/bin/arch32 stop

[Install]
WantedBy=multi-user.target

/usr/local/bin/arch32

#!/bin/bash

# Add '/var/run /var/lib/dbus' to the list to enable pulseaudio.
dirs=(/dev /dev/pts /dev/shm /tmp /home)

case $1 in
    start)
        for d in "${dirs[@]}"; do
            mount -o bind $d /opt/arch32$d
        done
        ;;
    stop)
        for (( i = ${#dirs[@]} - 1; i >= 0; i-- )); do
            umount "/opt/arch32${dirs[i]}"
        done
        umount /opt/arch32/{proc,sys}
        ;;
    *)
        echo "usage: $0 (start|stop)"
        exit 1
esac

Be sure to make the init script executable:

# chmod +x /usr/local/bin/arch32

Enable the service as any other systemd service.

Configure the new system

Configuration files

Key configuration files should be copied over:

cd /opt/arch32/etc

cp /etc/passwd* .
cp /etc/shadow* .
cp /etc/group* .
cp /etc/sudoers .  # note: you'll need to install sudo before creating this entry, or sudo will refuse to install

cp /etc/rc.conf .
cp /etc/resolv.conf .

cp /etc/localtime .
cp /etc/locale.gen .
cp /etc/profile.d/locale.sh profile.d

cp /etc/vimrc .
cp /etc/mtab .
cp /etc/sudoers .

Be sure to include the "." character.

Configure the chroot

Chroot into the new system:

/etc/rc.d/arch32 start
xhost +SI:localuser:usernametogiveaccesstogoeshere 
chroot /opt/arch32

It is recommended to use a custom bash prompt inside the 32-bit chroot installation in order to differentiate from the regular system. You can, for example, add a ARCH32 string to the PS1 variable defined in ~/.bashrc. In fact, the default Debian .bashrc prompt string contains appropriate logic to report whether the working directory is within a chroot.

Before continuing, keep in mind that the file /etc/pacman.conf from the 32-bit environment is the default one. Make sure to uncomment some mirrors in /etc/pacman.d/mirrorlist.

Fix possible locale issues:

/usr/sbin/locale-gen

Install the needed packages including apps, fonts, etc. for example:

pacman -S acroread opera
pacman -S firefox
pacman -S flashplugin
pacman -S mplayer-plugin

Regain space by removing some unnecessary packages.

Warning: This cleanup is for the 32-bit root environment and must then be done inside it NOT the native 64-bit environment!

The following shows recommended packages for removal:

pacman -Rd linux mkinitcpio
pacman -R dhcpcd ppp xfsprogs reiserfsprogs jfsutils logrotate lvm2 pcmciautils netcfg heirloom-mailx iputils iproute2 man-pages mdadm inetutils man-db cronie vi

Also consider regularly clearing out pacman's cache:

pacman -Scc

Install and Configure Schroot

Install "schroot" to the native 64-bit installation:

pacman -S schroot

Edit /etc/schroot/schroot.conf, and create an [Arch32] section.

[Arch32]
type=directory
profile=arch32
description=Arch32
directory=/opt/arch32
users=user1,user2,user3
groups=users
root-groups=root
personality=linux32
aliases=32,default

Optionally edit /etc/schroot/arch32/mount to match the mounts created within /etc/rc.d/arch32.

Using Schroot to run a 32-bit application

The general syntax for calling an application inside the chroot is:

schroot -p -- htop

In this example, htop is called from within the 32-bit environment.

Troubleshooting

Compilation and installing

Ensure the desired options are set in the local /etc/makepkg.conf.

Some packages may require a --host flag be added to the ./configure script in the PKBUILD:

./configure --host="i686-pc-linux" ...

This is the case when the build makes use of values (for example, the output of the uname command) inherited from your base system.

You may need to give users write access to your chroot's /dev/null to stop some scripts from failing:

chmod 666 /dev/null

Video issues

If you get:

X Error of failed request: BadLength (poly request too large or internal Xlib length error)

while trying to run an application that requires video acceleration, make sure you have installed appropriate video drivers in your chroot. For example,

pacman -S nvidia

Sound in flash (youtube, etc.)

To get sound from the flash player in Firefox, open a terminal and chroot inside the 32-bit system:

chroot /opt/arch32

From there, install alsa-oss:

pacman -S alsa-oss

Then type:

export FIREFOX_DSP="aoss"

Every chroot into the 32-bit system will require this export command to be entered so it may be best to incorporate it into a script.

Finally, launch Firefox.

For Wine this works the same way. The package alsa-oss will also install the alsa libs required by Wine to output sound.

Tips and tricks

Java in a chroot

See Java for installation instructions.

After installing, adjust the path to get Java working:

export PATH="/opt/java/bin/:$PATH"

arch32-light

Xyne has created a package that installs a minimalist 32-bit chroot as described above. More information can be found on the forum and on the project page.

Allowing 32-bit applications access to 64-bit Pulseaudio

Add these lines in /etc/rc.d/arch32, above add_daemon arch32:

mount --bind /var/run /opt/arch32/var/run
mount --bind /var/lib/dbus /opt/arch32/var/lib/dbus

And above rm_daemon arch32:

umount /opt/arch32/var/run
umount /opt/arch32/var/lib/dbus

More information is available at the Pulseaudio article, especially the section on Pulseaudio from within a chroot.

Enabling sound in Firefox

Open a text editor and save the following in /usr/bin/firefox32 as root:

#!/bin/sh
schroot -p firefox $1;export FIREFOX_DSP="aoss"

Make it executable:

sudo chmod +x /usr/bin/firefox32

Now you can make an alias for Firefox, if desired:

alias firefox="firefox32"

Add this to the end of file ~/.bashrc and source it to enable its usage. Or you can just change all your desktop environment's launchers to firefox32 if you still want 64-bit Firefox to be available.

Enabling 3D acceleration

In case you want to run any 32 bit application under your chroot with 3D acceleration (e.g. WINE, native 32 bit games) you simply need to install the corresponding libs as under your "native" arch.

For an ATI card using the radeon driver this could be:

pacman -S xf86-video-ati libgl ati-dri

For more informations on how to set up your graphic adapter refer to:

ATI

Intel

NVIDIA

Your can easily check if you have 3D rendering within the 32 bit chroot by installing mesa-demos and running the following command:

 glxinfo | grep renderer

If you have no 3D acceleration you'll get some output like this:

 [joe@arch64]$ OpenGL renderer string: Software Rasterizer

If 3D acceleration is enabled you'll get a message like this:

 [joe@arch64]$ OpenGL renderer string: Mesa DRI R600 (RV730 9490) 20090101 x86/MMX+/3DNow!+/SSE2 TCL DRI2

Script for wine

In order to compile wine, you need a 32-bit system installed. Compiling wine is needed for applying patches in order to get PulseAudio working. See also wine-hacks from AUR.

Add the following alias to ~/.bashrc:

alias wine='schroot -pqd "$(pwd)" -- wine'

The -q switch makes schroot operate in quiet mode, so it works like "regular" wine does. Also note that If you still use dchroot instead of schroot, you should use switch -d instead of -s.