The Gentoo Distribution

http://www.gentoo.org/

Joshua Sled

http://asynchronous.org/jsled

http://asynchronous.org/preso/vague/gentoo

The Gentoo Distribution

• Overview
• Features
• Philosophy
• Structure
• Packages / Portage
• Support

Overview

• Source-based "meta-distribution".
• Started in 1999 by Daniel Robbins.
• x86, AMD64, PowerPC, 32-bit and 64-bit Sparc, Alpha, IA64, S/390, HPPA, ARM, and MIPS
• Active, all-volunteer developer community.

Features

• recent glibc, gcc, ext3/ReiserFS/XFS/JFS, ALSA, pcmcia-cs, USB.
• SELinux, PaX/Grsecurity, Propolice
• Xfree86, XOrg, KDE, Gnome
• qmail++, postfix, exim.
• devfs, udev, GRUB, lilo/milo/silo, yaboot, BootX.
• Multiple kernel possibilities
  • Vanilla 2.4, 2.6, aa-, ac-, ck-, gentoo-, mm-, openmosix-, ppc-, rsbac-, uclinux-, xbox- sources.
  • Gentoo kernels with preempt, low latency, EVMS.
• Prelinking, ccache, distcc.

Philosophy and Social Contract

Philosophy

• The user has work to do: let them do it.
• Allow user to express will about their system, not tool-author's or package-maintainer's.

Social Contract

• OSI-approved licenses: GPL-2 and LGPL especially.
• Never depend on non-free software (but not excluded – the user might want that).
• Always freely available.
• Open development and bug process, upstream submission.

Structure

• Top-Level Projects
  • apache, council, forums, java, portage, base, desktop, devrel, documentation, eselect, gentoo-alt, hardened, infrastructure, kernel, metastructure, pr, qa, releng, security
• council - Elected, makes project-wide decisions; slacker rules.
• metastructure - Concerned with the structure of the Projects.
  • GELP - Gentoo Linux Enhancement Proposals
    • e.g. GELP 42: Critical News Reporting — A mechanism for ebuilds to record persistent news items, and a tool for reviewing them.
• security - Gentoo Linux Security Announcements (GLSA)
  • In-development glsa-check util.

Portage

• Soul of Gentoo.
• BSD ports-inspired.
• Written in bash + shell-utils and python.
• Framework for shell-scripts describing package building.
• Synchronized against Gentoo-provided copy.

Portage Features

• download sources, patch, configure, build, install
• ebuild files specify dependency requirements, package-specific config/build behavior.
• Virtuals (virtual/java)
• USE flags: conditional feature selection
  • Generally map to ./configure options.
  • Global (USE="-gnome kde qt arts -nls python perl oggvorbis opengl sdl -postgres jpeg png truetype dvd avi aalib mpeg encode fbcon mmx")
  • Local (gencertdaily for qmail)
• Masking: stable vs. unstable flag, per-platform.
• Slotting: multiple versions of the same package, side-by-side.
• Overlay trees.

Basic ebuild.

# /usr/portage/sys-apps/coreutils/coreutils-5.2.1-r6.ebuild
PATCH_VER=0.11
PATCHDIR="${WORKDIR}/patch"

DESCRIPTION="Standard GNU file utilities (chmod, cp, dd, dir, ls...), text utilities (sort, tr, head, wc..), and shell utilities (whoami, who,...)"
HOMEPAGE="http://www.gnu.org/software/coreutils/"
SRC_URI="mirror://gnu/${PN}/${P}.tar.bz2
	mirror://gentoo/${P}.tar.bz2
	mirror://gentoo/${P}-patches-${PATCH_VER}.tar.bz2
	http://dev.gentoo.org/~vapier/dist/${P}-patches-${PATCH_VER}.tar.bz2"

LICENSE="GPL-2"
SLOT="0"
KEYWORDS="alpha amd64 arm hppa ia64 m68k mips ppc ppc64 s390 sh sparc x86"
IUSE="acl build nls selinux static"

RDEPEND="selinux? ( sys-libs/libselinux )
	acl? ( sys-apps/acl sys-apps/attr )
	nls? ( sys-devel/gettext )
	>=sys-libs/ncurses-5.3-r5"
DEPEND="${RDEPEND}
	>=sys-apps/portage-2.0.49
	=sys-devel/automake-1.8*
	>=sys-devel/autoconf-2.58
	>=sys-devel/m4-1.4-r1
	sys-apps/help2man"

src_unpack() {
	unpack ${A}
	cd "${S}"
  

Overrides

• /etc/portage/package.use

  # 2005.05.04; compilation triggers GCC bugs in ASM... :(
  # See http://bugs.gentoo.org/buglist.cgi?[...]
  media-video/ffmpeg -mmx

• /etc/portage/package.mask

  # 2005.08.19 -- kernel recompile needed
  =x11-base/x11-drm-20050502

• /etc/portage/package.unmask

  # 2005.06.08, jsled, adventure!
  =dev-java/sun-jdk-1.5.0*
  =dev-java/java-sdk-docs-1.5.0*

• /etc/portage/package.keywords

  # 2005.10.18 -- evo 2.4.x
  =mail-client/evolution-2.4.1 ~x86
  =gnome-extra/evolution-data-server-1.4.1 ~x86
  =gnome-extra/libgtkhtml-3.8.1 ~x86
  
  # 2005-11-10 -- openoffice 2.0
  =app-office/openoffice-bin-2.0.0 ~x86

Portage Usage

• emerge, ebuild, equery
• emerge --sync \
&& emerge --update world — keeps whole system up to date.
  • Weekly? Monthly?
  • 1 year = 1 weekend (3-year-old Athlon XP+)
  • Periodic "profile" changes
• etc-update — interactive config file update merging.
• revdep-rebuild — reverse-dependency check
• emerge --binpkg — creates binary package from locally-built

Installer

• No graphical installer; detailed manual install instructions.
• Gentoo Reference Platform pre-compiled binaries.
• Install Stages...
  • Stage 1: Nothing. Bootstrap; compile gcc, glibc, system, kernel, user environment.
  • Stage 2: Bootstrapped. Compile system, kernel and user environment.
  • Stage 3: Base system. Compile kernel, boot manager.
  • ... as of Mon (2005-11-14), the install guide encourages Stage 3 with optional Stage 1/2.
• ISOs and LiveCDs available most arches.

Support/Community

• Large, active community.
• irc://irc.freenode.net/gentoo - very busy...
• #gentoo-{x86,sparc,...,
        java,python,...,
        hardened,security,...,
        web,mythtv,laptop,kde,...}:
  119 channels
• http://forums.gentoo.org, http://packages.gentoo.org, http://bugs.gentoo.org
• Easy to create ebuilds -> lots of user-submitted ebuilds (plus overlay trees).
• Documentation
  • Gentoo Handbook
  • Lots of HOWTOs, FAQs
  • Ebuild/Portage docs

Gentoo Linux

• Source-based distribution.
• Building from source
  • flexibility
  • time, energy
• Active support infrastructure.