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Chroot de 32-bit
Desde la versión 1.3 Funtoo Linux termina el soporte para las aplicaciones de 32 bits y las bibliotecas de x86-64 con multilib -- Para más información mire este post en los foros. Esta página le proporcionará detalles de porque se tomó esta desición y algunos pasos que pueden ser utilizados para obtener soporte de 32 bits sin multilib, mejor conocido como un entorno chroot de 32 bits.
Preámbulo
La x86 Instruction Set Architecture incluye registros 64-bit que se han implementado en los procesadores, desde AMD, Intel y otros comenzando desde el 2003 (AMD Opteron).
Desde entonces, la mayoría de las aplicaciones nuevas y existentes se han escrito para utilizar la arquitectura x86-64bit. Menos aplicaciones requieren soporte de 32 bits. En el pasado, la arquitectura x86-64bit en Funtoo Linux ha brindado soporte para aplicaciones y bibliotecas de 64 y 32 bits simultáneamente, llamado 'multilib', que es una de las capacidades que forman parte de la biblioteca GNU C y el cargador dinámico de bibliotecas.
Sin embargo, el soporte multilib hace que el mantenimiento de los ebuilds sea más complejo, y hemos tenido instrucciones de 64 bits durante más de 15 años, y cada vez menos cosas realmente necesitan soporte de 32 bits. Por lo tanto, tiene sentido comenzar a realizar la transición a un entorno puro de 64 bits sin multilib para reducir la complejidad de los ebuilds, y analizar otros enfoques para resolver el problema de compatibilidad de 32 bits.
Opciones
Los usuarios que necesitan ejecutar programas de 32 bits en hardware x86-64bit tienen varias opciones:
- Instalar una segunda instancia separada de Funtoo Linux usando construcciones de arquitectura x86-32bit.
- Instalar una instancia de arquitectura x86-32bit de Funtoo Linux en un host x86-64bit. Luego, los usuarios entran en el entorno de 32 bits usando el comando
linux32(es decir,setarch) proporcionado por No results. Esta guía detallará la configuración y el uso de este segundo escenario. - Usar LXD para configurar un contenedor de 32 bits.
Consulte Chroot and Containers para obtener una lista completa de las opciones documentadas en la wiki.
Installation
This guide describes a 32-bit chroot installed into a new directory on existing storage.
user $ su - Password: root # mkdir -p /path/to/chroot/directory root # cd /path/to/chroot/directory
Similar to a Funtoo installation an appropriate Stage3 tarball must be downloaded and extracted. This will provide the directories, files and links necessary for the 32-bit chroot.
Please refer to the Subarches page for an appropriate 32-bit Stage3. The following x86-32bit builds would be appropriate on an x86-64bit host
| Subarch | CPU Family |
|---|---|
| Generic 32 | 32-bit Processors (PC-Compatible, Generic) |
| I686 | 32-bit Processors (PC-Compatible, Generic) |
| Atom 32 | 32-bit Intel Processors |
| Pentium4 | 32-bit Intel Processors |
You should choose a 32-bit subarch with features and CPU_FLAGS that are compatible with the subarch and CPU of your x86-64bit host. If in doubt, choose 'Generic 32'.
Copy the download link address for the 1.3-release-std build and paste it into your terminal to download using wget.
root # wget https://build.funtoo.org/1.3-release-std/x86-32bit/generic_32/2018-12-13/stage3-generic_32-1.3-release-std-2018-12-13.tar.xz
From within your 32-bit chroot directory, run the following command to extract the Stage3 tarball, preserving permissions:
root # tar -xpf stage3-generic_32-1.3-release-std-2018-12-13.tar.xz
Instead of having duplicate portage trees, this 32-bit chroot will instead use the meta-repo of the 64-bit host. To further eliminate duplicate downloads you can also use the local Portage sourcefile directory on the host inside of the chroot (see 'DISTDIR' in emerge --info). Package source files already fetched by the host will then be available for use by Portage inside of the chroot.
To achieve this you must first create the necessary directories inside of the 32-bit chroot folder. Later the host folders will bind-mount onto these empty directories.
root # mkdir -p var/git/meta-repo root # mkdir -p var/cache/portage/distfiles
sys-apps/portage and other packages must only see the environment variables of the 32-bit chroot and not those of the 64-bit host. The Gentoo guide requires users to execute env-update each time you enter the 32-bit chroot environment. The following configuration will set this to occur automatically.
Create and edit the file .bash_profile inside of the directory /part/to/chroot/directory/root/ to include the following
root # nano root/.bash_profile
.bash_profile - /root/.bash_profile inside of /path/to/chroot/directory/#run env-update on 32-bit chroot login
env-update
As the last step you should configure app-shells/bash to display a modified command prompt while inside of the chroot environment. This will help you to identify when you are issuing commands inside of the 32-bit chroot as opposed to the x86-64bit host.
Add the following line at the end of the file profile inside of the directory /part/to/chroot/directory/etc/
root # nano etc/profile
profile - /etc/profile inside of /path/to/chroot/directory/# understand sequences such as \h, don't put anything special in it.
PS1="${USER:-$(whoami 2>/dev/null)}@$(uname -n 2>/dev/null) \$ "
fi
# ADD THE FOLLOWING LINE TO IDENTIFY YOUR 32-BIT CHROOT ENVIRONMENT
PS1="(32-bit chroot) ${PS1}"
for sh in /etc/profile.d/*.sh ; do
[ -r "$sh" ] && . "$sh"
done
unset sh
OpenRC Configuration
You can create an sys-apps/openrc service named chroot32 to automatically copy files and mount directories prior to accessing the 32-bit chroot environment. This service will include additional mounts for meta-repo and the Portage DISTDIR.
The following file mounts Funtoo portage tree /var/git/meta-repo as read-only. The Portage DISTDIR (/var/cache/portage/distfiles) is mounted read-write.
Create and edit the file /etc/init.d/chroot32, setting chroot_dir to equal /path/to/chroot/directory.
root # nano /etc/init.d/chroot32
chroot32 - /etc/init.d/chroot32 on x86-64bit host#!/sbin/openrc-run
chroot_dir=/path/to/chroot/directory
depend() {
need localmount bootmisc
}
start() {
ebegin "Mounting 32-bit chroot directories"
mount --rbind /dev "${chroot_dir}/dev" >/dev/null
mount --rbind /sys "${chroot_dir}/sys" >/dev/null
mount -t proc none "${chroot_dir}/proc" >/dev/null
mount -o bind /tmp "${chroot_dir}/tmp" >/dev/null
mount -o bind,ro /var/git/meta-repo "${chroot_dir}/var/git/meta-repo/" >/dev/null
mount -o bind /var/cache/portage/distfiles "${chroot_dir}/var/cache/portage/distfiles/" >/dev/null
mount -t tmpfs -o nosuid,nodev,noexec,mode=755 none "${chroot_dir}/run" > /dev/null
eend $? "An error occured while attempting to mount 32bit chroot directories"
ebegin "Copying 32bit chroot files"
cp -pf /etc/resolv.conf /etc/passwd /etc/shadow /etc/group \
/etc/gshadow /etc/hosts "${chroot_dir}/etc" >/dev/null
cp -Ppf /etc/localtime "${chroot_dir}/etc" >/dev/null
eend $? "An error occured while attempting to copy 32 bits chroot files."
}
stop() {
ebegin "Unmounting 32-bit chroot directories"
umount -fR "${chroot_dir}/dev" >/dev/null
umount -fR "${chroot_dir}/sys" >/dev/null
umount -f "${chroot_dir}/proc" >/dev/null
umount -f "${chroot_dir}/tmp" >/dev/null
umount -f "${chroot_dir}/var/git/meta-repo/" >/dev/null
umount -f "${chroot_dir}/var/cache/portage/distfiles/" >/dev/null
umount -f "${chroot_dir}/run"
eend $? "An error occured while attempting to unmount 32bit chroot directories"
}
Set this file to be executable.
root # chmod +x /etc/init.d/chroot32
Start the chroot32 service to prepare the 32-bit environment.
root # rc-service chroot32 start | * Mounting 32-bit chroot directories... [ ok ] | * Copying 32bit chroot files... [ ok ]
If you would like this service to run during host startup issue the following command
root # rc-update add chroot32 default * service chroot32 added to runlevel default
The 32-bit chroot environment is now ready for access.
Enter 32-bit Chroot
Enter the 32-bit chroot environment with the following commands
user $ su - Password: ******* root # linux32 chroot /path/to/chroot/directory /bin/bash -l >>> Regenerating /etc/ld.so.cache... chroot32 #
The switch -l tells bash to source /etc/profile within the chroot environment and not from the host. Without this switch you must manually issue the command source /etc/profile each time you enter the 32-bit environment.
Confirm that you are now in a 32-bit environment
chroot32 # uname -m i686 chroot32 # epro show === Enabled Profiles: === arch: x86-32bit build: current subarch: generic_32 flavor: core mix-ins: (not set) === Python kit: === branch: 3.7-release === All inherited flavor from core flavor: === minimal (from core flavor)
Chroot First Steps
If necessary now is a good point to set up Localization. Similarly, changes to /etc/portage/make.conf within the 32-bit environment can be made.
Currently you are the root user inside of the 32-bit environment. To change to the host user account localuser you must first create a home directory for localuser inside the 32-bit environment. (/home/localuser on the host is not mounted inside of this chroot environment.)
chroot32 # cp -r /etc/skel /home/localuser chroot32 # chown -R localuser:localuser /home/localuser
Switch to 'localuser'
chroot32 # su localuser -l user $
Updating Funtoo Meta-Repo
The 32-bit chroot environment uses the Meta-Repo (/var/git/meta-repo) of the 64bit host. Issuing ego sync is not necessary within the 32-bit chroot environment.
You must update Meta-Repo on the x86-64bit host before entering the 32-bit environment.
Exiting the 32-bit Chroot
chroot32 # exit root #
Emerging Packages
Enter the 32-bit chroot environment and install packages normally.
user $ su - Password: ******* root # chroot /path/to/chroot/directory /bin/bash -l >>> Regenerating /etc/ld.so.cache... chroot32 # emerge -av foobar
Depending on your use case it may be beneficial to change flavor and add mix-ins within the 32-bit environment.
Wine (32-bit only)
Before entering the 32-bit environment run the following command
user $ su - Password: ******* root # xhost local:localhost
This will allow X11 applications inside of the 32-bit environment to display on the host X session.
Install Wine inside of the 32-bit environment (example, No results)
chroot32 # emerge -av wine-vanilla
Instead of running wine as the root user, run as localuser. Switch to 'localuser' and configure Wine with winecfg. An X window should display.
chroot32 # su localuser -l chroot32 # winecfg
Acknowledgement
The information published here is based on steps detailed on the Gentoo Linux Wiki: https://wiki.gentoo.org/wiki/Project:AMD64/32-bit_Chroot_Guide (CC BY-SA 3.0).