Leitfaden zur Nutzung von Binärpaketen

Portage - the heart of Gentoo
emerge — configuration — ebuild repository — dispatch-conf

world file — USE flags — ebuilds — profiles
upgrades — using testing packages — binary packages
tools — gentoolkit — eselect
Portage FAQ — cheat sheet — FAQ
all articles

Neben der gewöhnlichen Unterstützung von quell-basierten ebuilds bietet Portage auch den Bau und die Installation von Binärpaketen. . Dieser Leitfaden erklärt wie man diese erstellt, installiert und wie man einen Binärpaket-Server aufsetzt.

Es gibt viele Gründe, weshalb einige Systemadministratoren die Verwendung von Binärpaketen für Softwareinstallationen unter Gentoo mögen:

• Zeitersparnis bei der Aktualisierung ähnlicher Systeme. Alles aus den Quellen kompilieren zu müssen, kann zeitaufwändig werden. Die Wartung einiger ähnlicher Systeme, möglicherweise einige von ihnen mit älterer Hardware, kann sehr viel einfacher sein, wenn nur ein System alles aus den Quellen kompilieren muss und die anderen Systeme die Binärpakete verwenden.
• Sichere Updates durchzuführen. Für missionskritische Systeme in Produktionsumgebungen ist es wichtig soweit wie möglich benutzbar zu bleiben. Dies kann durch Staging-Server erreicht werden, die alle Updates zuerst bei sich selbst durchführen. Sobald der Staging-Server (wieder) in einem guten Zustand ist, können die Updates auf das kritische System angewandt werden. Eine Variante dieses Ansatzes ist die Updates in einer chroot-Umgebung auf dem selben System durchzuführen und die hierbei erzeugten Binärdateien dann im richtigen System zu benutzen.
• Als ein Backup. Oft sind Binärpakete der einzige Weg ein kaputtes System wiederherzustellen (z.B. kaputter Kompiler). Vorkompilierte Binärpakete bei der Hand zu haben, entweder auf einem Binärpaket-Server oder lokal, kann im Falle einer defekten Toolchain eine große Hilfe sein.
• Und schließlich hilft es ebenfalls sehr alte Systeme upzudaten. Die Aufgabe sehr alte Systeme upzudaten kann durch die Verwendung von Binärpaketen stark vereinfacht werden. Es ist für gewöhnlich hilfreich Binärpakete auf alten Systemen zu installieren weil sie keine Build-Time Abhängigkeiten erfordern, die installiert/ upgedatet werden müssten. Binär-Pakete vermeiden ebenfalls Fehler in Build-Prozessen, weil sie vorkompiliert sind.

Dieser Leitfaden konzentriert sich auf die folgenden Themen:

• Using binary packages.
• Creating binary packages.
• Distributing the packages to clients.
• Maintaining the binary packages.

Nahe am Ende werden ein paar fortgeschrittenere Themen zum Umgang mit Binärpaketen behandelt.

Hinweis
Alle in diesem Leitfaden verwendeten Tools sind Teil von sys-apps/portage, soweit nicht anders angegeben.

Binärpaketformate

Two binary package formats for use in Gentoo exist, XPAK and GPKG. Starting with v3.0.31, Portage supports the new binary package format GPKG. The GPKG format solves issues with the legacy XPAK format and offers the benefit of new features, however it is not backward compatible with the legacy XPAK format.

System administrators using older versions of Portage (<=v3.0.30) should continue to continue to use the legacy XPAK format, which is Portage's default setting.

Motivation for the newer GPKG format design can be found in GLEP 78: Gentoo binary package container format. Bugs bug #672672 and bug #820578 also provide helpful details.

To instruct Portage to use the GPKG format, change the BINPKG_FORMAT value in /etc/portage/make.conf.

DATEI /etc/portage/make.confSpecify GPKG binary package format

BINPKG_FORMAT="gpkg"

This guide mostly applies to both formats; where this is not the case it will be noted. See the Understanding the binary package format section for technical details on the binary package formats themselves.

Verwendung von Binärpaketen

General prerequisites

Damit Binärpakete auf anderen Systemen verwendet werden können, müssen sie einige Anforderungen erfüllen:

• Die Client- und Server-Prozessorarchitektur und CHOST müssen übereinstimmen.
• Die CFLAGS und CXXFLAGS Variablen, die zum Bau der Pakete verwendet werden, müssen mit allen Clients kompatibel sein.
• USE-Flags für prozessorspezifische Befehlssatzmerkmale (wie MMX, SSE usw.) müssen sorgfältig ausgewählt werden; alle Clients müssen sie unterstützen.

Hinweis
Binary packages that are distributed as part of Gentoo's official Binhost project use a minimum instruction set and conservative compiler settings in order to be as widely usable as possible. By way of example, amd64 keyworded packages are built with -march=x86-64 -mtune=generic, which works for any machine which runs the x86-64 (amd64) instruction set.

Wichtig
Portage kann nicht überprüfen, ob diese Anforderungen übereinstimmen. Es liegt in der Verantwortung des Systemadministrators, diese Einstellungen zu überwachen.

Handling *FLAGS in detail

The app-misc/resolve-march-native utility can be used to find a subset of CFLAGS that is supported by both the server and client(s). For example, the host might return:

user $resolve-march-native

 -march=skylake -mabm -mrtm --param=l1-cache-line-size=64 --param=l1-cache-size=32 --param=l2-cache-size=12288 

While the client might return:

user $resolve-march-native

 -march=ivybridge -mno-rdrnd --param=l1-cache-line-size=64 --param=l1-cache-size=32 --param=l2-cache-size=3072 

In this example CFLAGS could be set to -march=ivybridge -mno-rdrnd since -march=ivybridge is a full subset of -march=skylake. -mabm and -mrtm are not included as these are not supported but the client. However, -mno-rdrnd is included as the client does not support -mrdrnd. To find which -march's are subsets of others, check the gcc manual, if there is no suitable subset set e.g. -march=x86-64.

Optionally, it is also possible to set -mtune=some-arch or -mtune=native to tell gcc to tune code to a specific arch. In contrast to -march, the -mtune argument does not prevent code from being executed on other processors. For example, to compile code which is compatible with ivybridge and up but is tuned to run best on skylake set CFLAGS to -march=ivybridge -mtune=skylake. When -mtune is not set it defaults to whatever -march is set to.

When changing -march to a lower subset for using binary packages on a client, a full recompilation is required to make sure that all binaries are compatible with the client's processor, to save time packages that are not compiled with e.g. gcc/clang can be excluded:

user $emerge -e @world --exclude="acct-group/* acct-user/* virtual/* app-eselect/* sys-kernel/* sys-firmware/* dev-python/* dev-java/* dev-ruby/* dev-perl/* dev-lua/* dev-php/* dev-tex/* dev-texlive/* x11-themes/* */*-bin"

Similarly, app-portage/cpuid2cpuflags can be used to find a suitable subset of processor specific instruction set USE flags. For example, the host might return:

user $cpuid2cpuflags

 CPU_FLAGS_X86: aes avx avx2 f16c fma3 mmx mmxext pclmul popcnt rdrand sse sse2 sse3 sse4_1 sse4_2 ssse3 

While the client might return:

user $cpuid2cpuflags

 CPU_FLAGS_X86: avx f16c mmx mmxext pclmul popcnt sse sse2 sse3 sse4_1 sse4_2 ssse3 

In this example CPU_FLAGS_X86 can be set to avx f16c mmx mmxext pclmul popcnt sse sse2 sse3 sse4_1 sse4_2 ssse3 in /etc/portage/make.conf because these flags are supported by both the client and the host

Next to these, Portage will check if the binary package is built using the same USE flags as expected on the client. If a package is built with a different USE flag combination, Portage will either ignore the binary package (and use source-based build) or fail, depending on the options passed to the emerge command upon invocation (see Installing binary packages).

On clients, a few configuration changes are needed in order for the binary packages to be used.

Installation von Binärpaketen

There are a few options that can be passed on to the emerge command that inform Portage about using binary packages:

Option	Description
--usepkg (-k)	Tries to use the binary package(s) in the locally available packages directory. Useful when using NFS or SSHFS mounted binary package hosts. If the binary packages are not found, a regular (source-based) installation will be performed.
--usepkgonly (-K)	Similar to --usepkg (-k) but fail if the binary package cannot be found. This option is useful if only pre-built binary packages are to be used.
--getbinpkg (-g)	Download the binary package(s) from a remote binary package host. If the binary packages are not found, a regular (source-based) installation will be performed.
--getbinpkgonly (-G)	Similar to --getbinpkg (-g) but will fail if the binary package(s) cannot be downloaded. This option is useful if only pre-built binary packages are to be used.

In order to automatically use binary package installations, the appropriate option can be added to the EMERGE_DEFAULT_OPTS variable:

DATEI /etc/portage/make.confAutomatisches Abrufen von Binärpaketen und Fehlschlagen des Pakets, wenn es nicht verfügbar ist

EMERGE_DEFAULT_OPTS="${EMERGE_DEFAULT_OPTS} --getbinpkgonly"

There is a Portage feature that automatically implements the equivalent of --getbinpkg (-g) without the need for updating the EMERGE_DEFAULT_OPTS variable with the --getbinpkg value:

DATEI /etc/portage/make.confAktivieren von getbinpkg in der Variable FEATURES

FEATURES="getbinpkg"

Überprüfen der OpenPGP-Signatur des Binärpakets

Wichtig
OpenPGP signing and verification is only available for the GPKG binpkg format.

Portage will try to verify the binary package's signature whenever possible, but users must first set up trusted local keys. app-portage/getuto can be used to set up a local trust anchor and update the keys in /etc/portage/gnupg. It is planned that portage will do this automatically at some point, but for now, users have to call getuto manually as root:

root #getuto

This configures portage such that it trusts the Gentoo Release Engineering keys as also contained in the package sec-keys/openpgp-keys-gentoo-release for binary installation purposes.

Changes to the configuration can be done as root using gpg with the parameter --homedir=/etc/portage/gnupg. This way you can import additional signing keys (e.g. for non-standard installation sources) and declare them as trusted.

By default, Portage will only verify GPG signatures when a signature file is found in a package, which allows the user to mix signed and unsigned GPKG binary packages from different sources, and allows to use of old XPAK format binary packages.

If the user needs to force signature verification, the binpkg-request-signature feature needs to be enabled. This feature assumes that all packages should be signed and rejects any unsigned package. Note that this feature does not support per binhost configuration.

DATEI /etc/portage/make.confEnabling Portage's binpkg-request-signature feature

FEATURES="binpkg-request-signature"

Pakete von einem Binärpaket-Host abrufen

Warnung
"The PORTAGE_BINHOST variable is deprecated in favor of the /etc/portage/binrepos.conf configuration file" - make.conf(5)

When using a binary package host, clients need to have the PORTAGE_BINHOST variable set in /etc/portage/make.conf or the sync-uri variable in /etc/portage/binrepos.conf. The latter option using /etc/portage/binrepos.conf is preferred. Without this configuration, the client will not know where the binary packages are stored which results in Portage being unable to retrieve them.

DATEI /etc/portage/binrepos.confSetting binhost sync-uri

[binhost]
sync-uri = https://example.com/binhost
priority = 10

For each binhost, a name can be configured in the brackets. sync-uri must point to the directory in which the Packages file resides. Optionally, priority can be set. When a package exists in multiple binary package repositories, the package is pulled from the binary package host with the highest priority. This way, a preferred binary package host can be set up.

Many Gentoo stages already come with a preinstalled /etc/portage/binrepos.conf file, which points to the corresponding binary packages generated during the stage builds.

Hinweis
The support for multiple binary package servers is somewhat incomplete. If several servers serve a binary package for the same package version, then only the first one will be considered. This can be problematic when these binary packages differ in their USE variable configuration and the USE variable configuration of a later binary package would match the systems configuration.

Neuinstallation von modifizierten Binärpaketen

Passing the --rebuilt-binaries option to emerge will reinstall every binary that has been rebuilt since the package was installed. This is useful in case rebuilding tools like revdep-rebuild are run on the binary package server.

A related option is --rebuilt-binaries-timestamp. It causes emerge not to consider binary packages for a re-install if those binary packages have been built before the given time stamp. This is useful to avoid re-installing all packages, if the binary package server had to be rebuild from scratch but --rebuilt-binaries is used otherwise.

Zusätzliche Client-Einstellungen

Next to the getbinpkg feature, Portage also listens to the binpkg-logs feature. This one controls if log files for successful binary package installations should be kept. It is only relevant if the PORT_LOGDIR variable has been set and is enabled by default.

Similar to excluding binary packages for a certain set of packages or categories, clients can be configured to exclude binary package installations for a certain set of packages or categories.

To accomplish this, use the --usepkg-exclude option:

root #emerge -uDNg @world --usepkg-exclude "sys-kernel/gentoo-sources virtual/*"

To enable such additional settings for each emerge command, add the options to the EMERGE_DEFAULT_OPTS variable in the make.conf file:

DATEI /etc/portage/make.confAktivieren der Emerge-Einstellungen bei jedem Aufruf

EMERGE_DEFAULT_OPTS="${EMERGE_DEFAULT_OPTS} --usepkg-exclude 'sys-kernel/gentoo-sources virtual/*'"

Updating packages on the binary package host

Wichtig
Do not use --changed-use(-U) when updating packages on the binary package host, doing so will cause packages with added or removed USE flags to be skipped, which will cause their installation from binary package on the client to fail due to non-matching USE between the source ebuild and binary package (if the client's --binpkg-respect-use=y, the default). Use --newuse(-N), which will always rebuild packages even for added or removed USE flags, ensuring the binary package stays in sync with the source ebuild.

Binärpakete erzeugen

Es gibt drei Hauptmethoden um Binärpakete zu erzeugen:

1. Nach einer regulären Installation durch Nutzung der quickpkg Anwendung;
2. Explizit währen einer emerge-Operation durch den Gebrauch der --buildpkg (-b) Option;
3. Automatisch durch die Verwendung des buildpkg (Binärpakete für alle Pakete erstellen) oder buildsyspkg (Binärpakete nur für den System set erstellen) Werts in Portages FEATURES Variable.

Alle drei Methoden erzeugen ein Binärpaket im Verzeichnis auf das durch die PKGDIR-Variable gezeigt wird (deren Voreinstellung /var/cache/binpkgs ist).

Benutzung von quickpkg

Die Applikation quickpkg (in Portage enthalten) nimmt eine oder mehrere Abhängigkeits-atome (oder Paket-Sätze) und erstellt für alle installierten Pakete die mit diesem atom übereinstimmen Binärpakete.

Wichtig
Bei dieser Methode gibt es einen Vorbehalt: Sie ist auf die installierten Dateien angewiesen, was im Fall von Konfigurationsdateien ein Problem sein kann. Administratoren ändern Konfigurationsdateien nach der Softwareinstallation oft. Aus diesem Grund können (vielleicht sogar vertrauliche) Daten in die Pakete entweichen. quickpkg schließt standardmäßig Konfigurationsdateien nicht ein, die mit der CONFIG_PROTECT Methode geschützt sind. Um die Erfassung von Konfigurationsdateien zu erzwingen nutzen Sie die --include-config oder --include-unmodified-config Option.

Um beispielsweise von allen installierten GCC-Versionen Binärpakete zu erstellen:

root #quickpkg sys-devel/gcc

To create binary packages for the system set:

root #quickpkg @system

Um Binärpakete von allen auf dem System installierten Paketen zu schaffen, verwenden Sie * glob:

root #quickpkg "*/*"

--buildpkg als emerge Option nutzen

Bei der Installation von Software mit emerge kann Portage mit der --buildpkg (-b) Option verwendet werden, um Binärpakete zu erstellen:

root #emerge --ask --buildpkg sys-devel/gcc

Es ist ebenfalls möglich Portage dazu zu bringen nur Binärpakete zu erzeugen aber die Software nicht auf dem Live-System zu installieren. Dazu kann die --buildpkgonly (-B) Option verwendet werden:

root #emerge --ask --buildpkgonly sys-devel/gcc

Die letztere Herangehensweise macht es erforderlich alle Build-Time Abhängigkeiten zuvor zu installieren.

Implementierung von buildpkg als Portage-Eigenschaft

Die gewöhnlichste Art um automatisch Binärpakete zu erzeugen wann immer ein Paket von Portage installiert wird, ist die Nutzung der buildpkg Eigenschaft. Sie kann auf die folgende Weise in /etc/portage/make.conf gesetzt werden:

DATEI /etc/portage/make.confAktivierung der buildpkg Eigenschaft von Portage

FEATURES="buildpkg"

Falls diese Eigenschaft aktiviert ist, wird jedes mal wenn Portage Software installiert, ebenfalls ein Binärpaket erzeugt.

Erzeugung einiger Pakete ausschließen

Es ist möglich, Portage anzuweisen für einige ausgewählte Pakete oder Kategorien keine Binärpakete zu erstellen. Dies geschieht durch Übergabe der --buildpkg-exclude Option zu emerge:

root #emerge -uDN @world --buildpkg --buildpkg-exclude "virtual/* sys-kernel/*-sources"

Dies könnte für Pakete verwendet werden, bei denen es wenig bis gar keinen Nutzen bring, ein Binärpaket zur Verfügung zu haben. Beispiele wären die Linux-Kernel-Quellpakete oder Upstream-Binärpakete (die mit "-bin" enden, wie www-client/firefox-bin).

Komprimierungsformate für Binärpakete

It is possible to use a specific compression type on binary packages. Currently, the following formats are supported: bzip2, gzip, lz4, lzip, lzop, xz, and zstd. Defaults to zstd. Review man make.conf and search for BINPKG_COMPRESS for the most up-to-date information.

The compression format can be specified via make.conf.

DATEI /etc/portage/make.confSpecify binary package compression format

BINPKG_COMPRESS="lz4"

Note that the compression type used might require extra dependencies to be installed, for example, in this case app-arch/lz4.

Signen des Binärpakets mit OpenPGP

Wichtig
OpenPGP signing and verification is only available for the GPKG binpkg format.

A PGP signature enables Portage to check the creator and integrity of a binary package, and to perform trust management based on PGP keys. The binary package signing feature is disabled by default. To use it, enable the binpkg-signing feature. Note that whether this feature is enabled does not affect the signature verification feature.

DATEI /etc/portage/make.confEnabling Portage's binpkg-signing feature

FEATURES="binpkg-signing"

Users also need to set the BINPKG_GPG_SIGNING_GPG_HOME and BINPKG_GPG_SIGNING_KEY variables for Portage to find the signing key.

DATEI /etc/portage/make.confConfiguring Portage's signing key

BINPKG_GPG_SIGNING_GPG_HOME="/root/.gnupg"
BINPKG_GPG_SIGNING_KEY="0x1234567890ABCDEF"

Portage will only try to unlock the PGP private key at the beginning. If the user's key will expire over time, then consider enabling gpg-keepalive to prevent signing failures.

DATEI /etc/portage/make.confEnabling Portage's gpg-keepalive feature

FEATURES="gpg-keepalive"

Einrichtung eines Binärpaket-Hosts

Portage unterstützt eine Reihe von Protokollen für das Herunterladen von Binärpaketen: FTP, FTPS, HTTP, HTTPS und SSH/SFTP. Dies lässt Raum für viele mögliche Implementierungen von Binärpaket-Hosts.

Es gibt jedoch keine "out-of-the-box" Methode, die von Portage für die Verteilung von Binärpaketen angeboten wird. Je nach gewünschten Setup muss zusätzliche Software installiert werden.

Webbasierter Binärpaket-Hosts

Ein gängiger Ansatz für die Verteilung von Binärpaketen ist die Erstellung eines webbasierten Binärpaket-Hosts.

Verwenden Sie einen Webserver wie lighttpd (www-servers/lighttpd) und konfigurieren Sie in so, dass er Lesezugriff auf /etc/portage/make.confs PKGDIR Verzeichnis hat.

DATEI /etc/lighttpd/lighttpd.confLighttpd Konfigurationsbeispiel

# Dies am Ende der Standardkonfiguration anfügen
server.dir-listing = "enable"
server.modules += ( "mod_alias" )
alias.url = ( "/packages" => "/var/cache/binpkgs/" )

Auf den Client-Systemen konfigurieren Sie dann die Variable PORTAGE_BINHOST entsprechend:

DATEI /etc/portage/make.confBenutzung eines webbasiertem Binärpaket-Hosts

PORTAGE_BINHOST="http://binhost.example.com/packages"

SSH-Binärpaket-Host

Um einen authentifizierten Ansatz für Binärpakete zu liefern, kann man SSH verwenden.

Bei der Verwendung von SSH ist es möglich, den SSH-Schlüssel des Root-Linux-Benutzers zu verwenden (ohne Passphrase, da die Installationen im Hintergrund erfolgen müssen), um eine Verbindung zu einem entfernten Binärpaket-Host herzustellen.

Stellen Sie dazu sicher, dass der SSH-Schlüssel des Root-Benutzers auf dem Server zugelassen ist. Dies muss für jeden Rechner geschehen, der eine Verbindung mit dem SSH-fähigen Binärpaket-Host herstellen will:

root #cat root.id_rsa.pub >> /home/binpkguser/.ssh/authorized_keys

Die PORTAGE_BINHOST Variable könnte dann wie folgt aussehen:

DATEI /etc/portage/make.confEinrichten von PORTAGE_BINHOST mit SSH-Zugang

PORTAGE_BINHOST="ssh://binpkguser@binhostserver/var/cache/binpkgs"

If the SSH server is listening to a different port (e.g 25), then it must be specified after the address, like so:

DATEI /etc/portage/make.confSetting PORTAGE_BINHOST for SSH access on port 25

PORTAGE_BINHOST="ssh://binpkguser@binhostserver:25/var/cache/binpkgs"

Hinweis
Verwenden Sie nicht die SSH-Konfigurationsdateien, die Sie in ~/.ssh/config finden, um den Port oder Benutzernamen zu setzen. Dieses Verzeichnis wird ignoriert, wenn Portage versucht, die Pakete mit rsync auf den Client zu übertragen. Setzen Sie stattdessen alle Optionen korrekt in der PORTAGE_BINHOST Variable.

NFS exportiert

Bei der Verwendung von Binärpaketen in einem internen Netzwerk kann es einfacher sein, die Pakete über NFS zu exportieren und sie auf den Clients einzuhängen.

Die /etc/exports Datei könnte wie folgt aussehen:

DATEI /etc/exportsExportieren des Paketverzeichnisses

/var/cache/binpkgs   2001:db8:81::/48(ro,no_subtree_check,root_squash) 192.168.100.0/24(ro,no_subtree_check,root_squash)

Auf den Clients kann das Verzeichnis dann eingehängt werden. Ein Beispiel für einen /etc/fstab-Eintrag würde so aussehen:

DATEI /etc/fstabEintrag zum Einhängen des Paketverzeichnisses

binhost:/var/cache/binpkgs      /var/cache/binpkgs    nfs    defaults    0 0

The NFS share is mounted on the local filesystem, so there is no need to set PORTAGE_BINHOST or use the --getbinpkg option. Instead, follow the normal procedures for installing binary packages, remembering to point PKGDIR to the NFS share so that portage knows where to find the packages:

DATEI /etc/portage/make.confSetting the package directory for portage

PKGDIR="/var/cache/binpkgs"

Hinweis
If PKGDIR is network-mounted, it may be advantageous to enable FEATURES="pkgdir-index-trusted". This feature disables checking the entire PKGDIR for added or removed packages and instead trusts the contents of the Packages file to be accurate. This significantly improves performance on high-latency networks.

Pflege von Binärpaketen

Exporting and distributing the binary packages will lead to useless storage consumption if the binary package list is not actively maintained.

Entfernen von veralteten Binärpaketen

In the app-portage/gentoolkit package an application called eclean is provided. It allows for maintaining Portage-related variable files, such as downloaded source code files, but also binary packages.

The following command will remove all binary packages that have no corresponding ebuild in the installed ebuild repositories:

root #eclean packages

For more details please read the Eclean article.

Another tool that can be used is the qpkg tool from the app-portage/portage-utils package. However, this tool is a bit less configurable.

To clean up unused binary packages (in the sense of used by the server on which the binary packages are stored):

root #qpkg -c

Pflege der Packages-Datei

Inside the packages directory exists a manifest file called Packages. This file acts as a cache for the metadata of all binary packages in the packages directory. The file is updated whenever Portage adds a binary package to the directory. Similarly, eclean updates it when it removes binary packages.

If for some reason binary packages are simply deleted or copied into the packages directory, or the Packages file gets corrupted or deleted, then it must be recreated. This is done using emaint command:

root #emaint binhost --fix

To clear the cache of all binary packages:

root #rm -r /var/cache/binpkgs/*

Fortgeschrittene Themen

Chrooting

If creating packages for a different Portage profile or system with different USE flags, a chroot can be created.

Hinweis
This example uses /var/chroot/buildenv as the chroot path, but any path can be used.

Creating the directories

First, the directories for this chroot must be created:

root #mkdir --parents /var/chroot/buildenv

Deploying the build environment

Next, the appropriate stage 3 tarball must be downloaded and extracted, here the desktop profile | openrc tarball is being used:

/var/chroot/buildenv/ #wget https://bouncer.gentoo.org/fetch/root/all/releases/amd64/autobuilds/20230528T163158Z/stage3-amd64-desktop-openrc-20230528T163158Z.tar.xz

This can be extracted with the following command:

/var/chroot/buildenv/ #tar xpvf stage3-*.tar.xz --xattrs-include='*.*' --numeric-owner

Configuring the build environment

Wichtig
{{{1}}}

The build environment should be configured to match that of the system it is building for. The simplest way to do this is to copy the /etc/portage and /var/lib/portage/world files. This can be done with scp:

Hinweis
This command should be executed on the build target machine, where the remote host has the chroot.

user $rsync --archive --whole-file --verbose /etc/portage/* larry@remote_host:/var/chroot/buildenv/etc/portage

user $rsync --archive --whole-file --verbose /var/db/repos/* larry@remote_host:/var/chroot/buildenv/var/db/repos

Hinweis
{{{1}}}

This process should be repeated for the world file:

user $rsync --archive --whole-file --verbose /var/lib/portage/world larry@remote_host:/var/chroot/buildenv/var/lib/portage/world

Hinweis
/var/lib/portage and /var/lib/portage/world should have the root:portage permissions.

Configuring the chroot

Once created, mounts must be bound for the chroot to work:

/var/chroot/buildenv #mount --types proc /proc proc

/var/chroot/buildenv #mount --rbind /dev dev

/var/chroot/buildenv #cp --dereference /etc/resolv.conf etc

Hinweis
If a tmpfs is being used for portage's temp dir, ensure that is mounted.

Entering the chroot

To enter this chroot, the following command can be used:

/var/chroot/buildenv #chroot /bin/bash

Optionally, the prompt can be set to reflect the fact that the chroot is active:

/ #export PS1="(chroot) $PS1"

Performing an initial build

Hinweis
This step assumes this configuration has been completed: Setting portage to use buildpkg.

This step is optional, but rebuilds all packages in the new world:

(chroot) #emerge --emptytree @world

Bauen für andere Architekturen

sys-devel/crossdev is a tool that will easily build cross compile toolchains to allow setting up a binary host for a different architecture, for example for a device like a Raspberry Pi from a more powerful desktop PC.

An installation guide for this package can be found at the Crossdev page.

Einen Cross-Compiler erstellen

Using crossdev with the following command can build a toolchain for the desired system:

root #crossdev --stable -t arch-vendor-os-libc

For the rest of this section, the example target will be for a Raspberry Pi 4:

root #crossdev --stable -t aarch64-unknown-linux-gnu

After this has built, a toolchain will have been created in /usr/aarch64-unknown-linux-gnu, and will look like a bare bones Gentoo install where it is possible to edit Portage settings as normal.

Tipp
Replacing aarch64-unknown-linux-gnu with aarch64-unknown-linux-musl would build a system with the Musl libc rather than Glibc.

Grundlegende Einrichtung

Removing the -pam flag from the USE line in /usr/aarch64-unknown-linux-gnu/etc/portage/make.conf is generally recommended in a setup like this:

DATEI /usr/aarch64-unknown-linux-gnu/etc/portage/make.confDisable the pam USE flag

CHOST=aarch64-unknown-linux-gnu
CBUILD=x86_64-pc-linux-gnu
 
ROOT=/usr/${CHOST}/
 
ACCEPT_KEYWORDS="${ARCH}"
 
USE="${ARCH}"
 
CFLAGS="-O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"
 
FEATURES="-collision-protect sandbox buildpkg noman noinfo nodoc"
# Ensure pkgs from another repository are not overwritten
PKGDIR=${ROOT}var/cache/binpkgs/
 
#If you want to redefine PORTAGE_TMPDIR uncomment (and/or change the directory location) the following line
PORTAGE_TMPDIR=${ROOT}var/tmp/
 
PKG_CONFIG_PATH="${ROOT}usr/lib/pkgconfig/"
#PORTDIR_OVERLAY="/var/db/repos/local/"

Profiles

List available profiles for the device by running:

root #PORTAGE_CONFIGROOT=/usr/aarch64-unknown-linux-gnu eselect profile list

Next, select the profile that best suits:

root #PORTAGE_CONFIGROOT=/usr/aarch64-unknown-linux-gnu eselect profile set <profile number>

Ein einzelnes Paket erstellen

To build a single binary package for use on the device, use the following:

root #emerge-aarch64-unknown-linux-gnu --ask foo

World-Datei erstellen

To build every package in the world file, then the following command is needed:

root #emerge-aarch64-unknown-linux-gnu --emptytree @world

Binary location

By default, all binary packages will be stored in /usr/aarch64-unknown-linux-gnu/var/cache/binpkgs, so this is the location needed to be selected when setting up a binary package host.

Creating snapshots of the packages directory

When deploying binary packages for a large number of client systems it might become worthwhile to create snapshots of the packages directory. The client systems then do not use the packages directory directly but use binary packages from the snapshot.

Snapshots can be created using the /usr/lib64/portage/python2.7/binhost-snapshot or /usr/lib64/portage/python3.3/binhost-snapshot tool. It takes four arguments:

1. A source directory (the path to the packages directory).
2. A target directory (that must not exist).
3. A URI.
4. A binary package server directory.

The files from the package directory are copied to the target directory. A Packages file is then created inside the binary package server directory (fourth argument) with the provided URI.

Client systems need to use an URI that points to the binary package server directory. From there they will be redirected to the URI that was given to binhost-snapshot. This URI has to refer to the target directory.

Verstehen des Binärpaketformats

XPAK-Format

XPAK format binary packages created by Portage have the file name ending with .tbz2. These files consist of two parts:

1. A .tar.bz2 archive containing the files that will be installed on the system.
2. A xpak archive containing package metadata, the ebuild, and the environment file.

See man xpak for a description of the format.

In app-portage/portage-utils some tools exists that are able to split or create tbz2 and xpak files.

The following command will split the tbz2 into a .tar.bz2 and an .xpak file:

user $qtbz2 -s <package>.tbz2

The .xpak file can be examined using the qxpak utility.

To list the contents:

user $qxpak -l <package>.xpak

The next command will extract a file called USE which contains the enabled USE flags for this package:

user $qxpak -x package-manager-0.xpak USE

GPKG-Format

GPKG format binary packages created by Portage have the file name ending with .gpkg.tar. These files consist of four parts at least:

1. A gpkg-1 empty file that used to identify the format.
2. A C/PV/metadata.tar{.compression} archive containing package metadata, the ebuild, and the environment file.
3. A C/PV/image.tar{.compression} archive containing the files that will be installed on the system.
4. A Manifest file containing checksums to protect against file corruption.
5. Multiple optional .sig files containing OpenPGP signature are used for integrity checking and verification of trust.

The format can be extracted by tar without the need for additional tools.

Das PKGDIR-Layout

The currently used format version 2 has the following layout:

CODE Layout des Pakete-Verzeichnisses (Version 2)

PKGDIR
`+- Packages
 +- app-accessibility/
 |  +- pkg1-version.tbz2
 |  `- pkgN-version.tbz2
 +- app-admin/
 |  `- ...
 `- ...

The Packages file is the major improvement (and also the trigger for Portage to know that the binary package directory uses version 2) over the first binary package directory layout (version 1). In version 1, all binary packages were also hosted inside a single directory (called All/) and the category directories only had symbolic links to the binary packages inside the All/ directory.

In portage-3.0.15 and later, FEATURES=binpkg-multi-instance is enabled by default:

CODE Packages directory layout (version 2 + FEATURES=binpkg-multi-instance)

PKGDIR
`+- Packages
 +- app-accessibility/
 |  +- pkg1/
 |    +- pkg1-version-build_id.xpak
 |    `- pkgN-version-build_id.xpak
 +- app-admin/
 |  `- ...
 `- ...

Entpacken mit quickunpkg

Zoobab wrote a simple shell tool named quickunpkg to quickly unpack tbz2 files.

External resources

quickpkg man page.