Global USE flags

Flag Description Packages
10bit Set output bit depth to 10, this may not be compatible with all decoders 2
X Enable support for e.g. fullscreen mode via X and the X C-language binding. It does not build a graphical interface 7
altivec 2
archive Enables support for accessing files in archives transparently via <pkg>app-arch/libarchive</pkg> 3
bluetooth Build Bluetooth protocol support in socket module 3
bluray Enable playback of Blu-ray filesystems using <pkg>media-libs/libbluray</pkg> 2
build 2
bzip2 compress the kernel with bzip2 3
cpu_flags_x86_sse 2
cpu_flags_x86_sse2 2
crypt Pull in <pkg>kde-plasma/plasma-vault</pkg> for encrypted vaults integration 2
crypto Enable crypto support 2
cxx 2
d3d9 Enable Ixit's Gallium Nine Patchset 2
dbus Enable dependencies required by glib libraries using dbus service to manage settings saving 3
debug 13
display-manager Pull in a graphical display manager 2
doc 21
elogind Use <pkg>sys-auth/elogind</pkg> for session tracking 3
examples Build example utilities 5
extras Build and install programs from the contrib directory 2
fontconfig 2
ftp install <pkg>net-ftp/filezilla</pkg> as the ftp client 2
gentoo-patches use the official gentoo patchset 2
gentoo-sources use the official gentoo kernel sources 2
gnome-keyring 3
gtk Enable Breeze widget style and KCM for GTK2 and GTK3 3
gtk-doc 5
gui Build FontForge with GUI support 2
http HTTP (Hypertext Transfer Protocol) 2
https Secure HTTP support 2
icu 3
idn 2
introspection 6
ipv6 3
jack 3
jpeg 3
kate install <pkg>kde-apps/kate</pkg> as your gui-based text editor 2
kerberos 2
l10n_zh-TW 2
ldap Enable seahorse to manipulate GPG keys on a LDAP server. 2
libressl 7
lto Build using Link Time Optimization, improves performance at the risk bugs may occur 2
lua Enable Lua scripting support, needed for including support for Jamendo (online music platform) and similar things 3
lz4 compress the kernel with lz4 2
lzma Enable support for XZ compressed modules 4
man generate man pages 4
minimal Do not install <pkg>x11-wm/openbox</pkg>window manager 2
mtp 2
ncurses 2
networkmanager 2
nfs Enable NFS client support via <pkg>net-fs/libnfs</pkg>. 2
nls Install <pkg>dev-qt/qttranslations</pkg> to better support different locales 4
opencl Enable OpenCL device discovery (AMD only) 4
opencv Enable OpenCV (computer vision) filter module 2
openssl 2
pax_kernel Enable if the user plans to run the package under a pax enabled hardened kernel 2
pf-sources use the pf kernel sources 2
pgo Build GCC using Profile Guided Optimization (PGO) 2
plugins Enable plugin support in tools 2
png 3
policykit 3
processviewer install <pkg>kde-plasma/ksysguard</pkg>, a full gui task manager 3
pulseaudio Install Plasma applet for PulseAudio volume management 4
python Build support for scripting via Python 3. 7
readline 3
rtsp Enable rtsp support 2
samba 3
screenshot Install <pkg>x11-misc/screengrab</pkg> package 2
sddm Pull in the <pkg>x11-misc/sddm</pkg> display manager and KCM 2
selinux 3
sftp support ssh file transfer protocol 3
ssh Enable SSH transport support 3
ssl Build support for TLS/SSL connections (RTMPS) via <pkg>net-libs/mbedtls</pkg>. 6
static-libs 12
sudo Install <pkg>lxqt-base/lxqt-sudo</pkg> 2
svg 4
systemd Add support for the systemd init system 4
systemtap Enable SystemTAP/DTrace tracing 3
terminal Install <pkg>x11-terms/qterminal</pkg> package 2
test 22
text-editor pull in kate, a full gui text editor 2
threads Enable threading support. (DON'T DISABLE THIS UNLESS YOU KNOW WHAT YOU'RE DOING) 4
tools Install additional tools 3
truetype 3
udev Enable udev base replacement code for cdda feature 2
unwind Enable stack backtraces (-k flag) via <pkg>sys-libs/libunwind</pkg> 2
utils Build various utilities 2
v4l Use libv4l2 for colorspace conversion 4
vaapi 3
vala 4
vanilla don't patch presets to make them easier to compare 3
vdpau Enable the VDPAU acceleration interface for the Gallium3D Video Layer. 3
verbose Verbose strings (disable to reduce size) 2
wayland Enable support for dev-libs/wayland 3
xattr Preserve extended attributes (filesystem-stored metadata) when installing files. Usually only required for hardened systems. 3
xml 3
zeroconf Enable support for zero-configuration networking via avahi 3
zlib Enable support for gzipped modules 4
zstd 3

Category USE flags

dev-libs

Flag Description Packages
trace Enable tracing support 2

gnome-base

Flag Description Packages
gnome-online-accounts Enable configuration panel for <pkg>net-libs/gnome-online-accounts</pkg> accounts 2

media-gfx

Flag Description Packages
tiff 2

media-libs

Flag Description Packages
egl Enable EGL support. 2
pic disable optimized assembly code that is not PIC friendly 2
vulkan Support for Vulkan 2

media-video

Flag Description Packages
alsa 2
fdk Enable libfdk support for AAC encoding. 2
speex Enable noise suppression filter support via <pkg>media-libs/speexdsp</pkg>. 2
vlc Build support for using <pkg>media-video/vlc</pkg> as a media source. 2

Local USE flags

app-admin

eselect

Flag Description
emacs
vim-syntax

app-arch

lzop

Flag Description
lld Add support for the lld linker

app-emulation

mars-mips

Flag Description
java

app-misc

radeontop

Flag Description
amdgpu amdgpu VRAM size and usage reporting (requires CONFIG_DEVMEM)
xcb Allow to run unprivileged in Xorg

tmux

Flag Description
utempter libutempter support - tmux will use utmp(5)
utf8proc Use utf8proc for unicode character processing

app-office

dia

Flag Description
cairo

app-text

docbook-xsl-stylesheets

Flag Description
fo fo
images images
params params
ruby Install the Ruby-based dbtoepub script; requires an interpreter compatible with <pkg>app-eselect/eselect-ruby</pkg>.
slides slides
webhelp webhelp

dev-cpp

cairomm

Flag Description
aqua

dev-db

sqlite

Flag Description
secure-delete Enable overwriting of deleted content with zeros by default (http://sqlite.org/pragma.html#pragma_secure_delete), causing some performance penalty
tcl

dev-lang

python

Flag Description
berkdb
elibc_uclibc
gdbm
hardened
l10n_et-EE
sqlite
tk
wide-unicode Enable wide Unicode implementation which uses 4-byte Unicode characters. Switching of this USE flag changes ABI of Python and requires reinstallation of many Python modules. (DON'T DISABLE THIS UNLESS YOU KNOW WHAT YOU'RE DOING)
wininst Install Windows executables required to create an executable installer for MS Windows.

rust

Flag Description
"(
${ALL_LLVM_TARGETS[*]}
(
)
)"
AArch64
AMDGPU
ARM
BPF
Hexagon
Lanai
MSP430
Mips
NVPTX
PowerPC
Sparc
SystemZ
WebAssembly
X86
XCore
cargo Install clippy, a linting tool
clippy
jemalloc Use <pkg>dev-libs/jemalloc</pkg> as the standard memory allocator
llvm_targets_WebAssembly
rls Install rls component
rustfmt Install rustfmt component
system-llvm Use system llvm
thumbv7neon Install arm optimisation
wasm Build support for the wasm32-unknown-unknown target

dev-libs

glib

Flag Description
elibc_glibc
fam Use fam for file system monitoring
iconv_gnu iconv_gnu
iconv_libc iconv_libc
iconv_native iconv_native
kernel_linux
libmount libmount
mime Pull in shared MIME database that many glib-based applications require at runtime to detect or open files. Warning: do not disable this flag unless installing on a headless server.

libgit2

Flag Description
curl Use <pkg>net-misc/curl</pkg> for HTTP support (otherwise, limited built-in implementation will be used)
gssapi Enable GSSAPI support for SPNEGO auth
https_mbedtls mbedTLS HTTPS backend
https_openssl OpenSSL HTTPS backend
sha1_collision_detection CollisionDetection SHA1 backend
sha1_generic Generic SHA1 backend
sha1_mbedtls mbedTLS SHA1 backend
sha1_openssl OpenSSL SHA1 backend

dev-python

pycurl

Flag Description
ssl_gnutls ssl_gnutls
ssl_nss ssl_nss
ssl_openssl ssl_openssl

dev-util

aseman-qt-tools

Flag Description
keychain keychain
multimedia multimedia
positioning positioning
sensors sensors
webenginewidgets webenginewidgets
webkitwidgets webkitwidgets
widgets widgets

clion

Flag Description
custom-jdk
system-clang Use <pkg>sys-devel/clang</pkg> instead of the bundled copy
system-cmake Use <pkg>dev-util/cmake</pkg> instead of the bundled copy
system-gdb Use <pkg>sys-devel/gdb</pkg> instead of the bundled copy
system-lldb Use <pkg>sys-devel/llvm</pkg> instead of the bundled copy

criterion

Flag Description
cpp Support for C++
theories Some tool for test-driven development

rider

Flag Description
mono Include mono, needed for regular .net and guis

smartgit

Flag Description
kernel up the memory limit to 3072 because the linux kernel really pushes memory limits
system-jre

spirv-tools

Flag Description
color-terminal color-terminal
compressing-codec compressing-codec
executables executables

strace

Flag Description
aio Enable <pkg>dev-libs/libaio</pkg> support for tracing Asynchronous I/O operations

games-simulation

firestorm-bin

Flag Description
fmod pull in <pkg>media-libs/fmod</pkg> for sound support

gnome-base

gnome-control-center

Flag Description
colord Support color management using <pkg>x11-misc/colord</pkg>
cups
flickr Add support for using photos from flickr as desktop background
ibus Enable support for enhanced input methods through <pkg>app-i18n/ibus</pkg>
input_devices_wacom
libinput
share
thunderbolt

gsettings-desktop-schemas

Flag Description
vanilla-fonts Don't patch in the ability to use other fonts. These are the hardcoded fonts GNOME originally envisioned.

gvfs

Flag Description
afp Enables support for accessing AFP (Apple Filing Protocol) network shares
cdda
fuse Enables fuse mount points in $HOME/.gvfs for legacy application access
google Enables support for accessing Google accounts via <pkg>dev-libs/libgdata</pkg>
gphoto2
ios
l10n_ms
udisks

kde-plasma

plasma-meta

Flag Description
browser-integration Enable integration with Chrome/Firefox with browser extensions
consolekit Enable <pkg>sys-auth/consolekit</pkg> support instead of logind session tracking
desktop-portal Enable <pkg>sys-apps/xdg-desktop-portal</pkg> backend implementation for Plasma
discover Pull in resources management GUI; a centralised GHNS alternative and optional <pkg>sys-apps/fwupd</pkg> frontend
grub Pull in Breeze theme for <pkg>sys-boot/grub</pkg>
handbook
legacy-systray Add support for legacy applications using <pkg>kde-plasma/xembed-sni-proxy</pkg>
pam Enable support for kwallet auto-unlocking
plymouth Pull in Breeze theme for <pkg>sys-boot/plymouth</pkg>
pm-utils Enable support for suspend/resume with <pkg>sys-power/pm-utils</pkg> when using <pkg>sys-auth/consolekit</pkg>
powerdevil Install power management software
sdk Pull in <pkg>kde-plasma/plasma-sdk</pkg> for Plasma development
task-manager install <pkg>kde-plasma/ksysguard</pkg>, a full gui task manager
wallpapers Install wallpapers for the Plasma Workspace

lxqt-base

lxqt-meta

Flag Description
about Install <pkg>lxqt-base/lxqt-about</pkg>
admin Install <pkg>lxqt-base/lxqt-admin</pkg>
archiver Install <pkg>app-arch/lxqt-archiver</pkg>
filemanager Install <pkg>x11-misc/pcmanfm-qt</pkg>file manager
lightdm Install <pkg>x11-misc/lightdm</pkg>display manager
lximage Install <pkg>media-gfx/lximage-qt</pkg>image viewer
onboard
powermanagement Install <pkg>lxqt-base/lxqt-powermanagement</pkg> package
qtvirtualkeyboard
screenlock Install light-weight screen lockers for xdg support
screensaver Install the full xscreensaver package
ssh-askpass Install <pkg>lxqt-base/lxqt-openssh-askpass</pkg> user password prompt tool
trash Install <pkg>gnome-base/gvfs</pkg> to enable 'trash' functionality in x11-misc/pcmanfm-qt
virtkeyboard

media-fonts

liberation-fonts

Flag Description
fontforge Use <pkg>media-gfx/fontforge</pkg> to build fonts from source

media-gfx

flameshot

Flag Description
l10n_

fontforge

Flag Description
gif
libspiro Add support for media-libs/libspiro
truetype-debugger Enable truetype debugger in fontforge
unicode
woff2 Enable support for WOFF2 format

imagemagick

Flag Description
corefonts Use <pkg>media-fonts/corefonts</pkg> which is required by some commands
djvu
fftw
fpx Enable <pkg>media-libs/libfpx</pkg> support
graphviz
hdri Enable High Dynamic Range Images formats
heif Enable support for ISO/IEC 23008-12:2017 HEIF/HEIC image format using <pkg>media-libs/libheif</pkg>
jbig
jpeg2k
lcms
lqr Enable experimental liquid rescale support using <pkg>media-libs/liblqr</pkg>
openexr
openmp
pango Enable Pango support using <pkg>x11-libs/pango</pkg>
perl
postscript
q32 Set quantum depth value to 32
q8 Set quantum depth value to 8
raw
webp
wmf

solvespace

Flag Description
spacenav add spacenav driver

media-libs

libepoxy

Flag Description
abi_x86_x32

libplacebo

Flag Description
bench build benchmarks

libvorbis

Flag Description
oggtest Build and run oggtest utility

libxcam

Flag Description
capi libxcam-capi
drm drm buffer
gst gstreamer plugin
libcl libcl image processor
profiling profiling
smartlib smart analysis lib

mesa

Flag Description
classic Build drivers based on the classic architecture.
dri3 Enable DRI3 support.
gallium Build drivers based on Gallium3D, the new architecture for 3D graphics drivers.
gbm Enable the Graphics Buffer Manager for EGL on KMS.
gles1 Enable GLESv1 support.
gles2 Enable GLESv2 support.
libglvnd Use libglvnd for dispatch.
llvm Enable LLVM backend for Gallium3D.
lm-sensors
omx-bellagio Uses the older Bellagio as the OpenMAX IL
omx-tizonia Uses the newer Tizonia as the OpenMAX IL
openmax Enable OpenMAX support
osmesa Build the Mesa library for off-screen rendering.
valgrind Compile in valgrind memory hints
video_cards_
video_cards_iris
video_cards_nouveau
video_cards_r300
video_cards_r600
video_cards_radeonsi
video_cards_vmware
vulkan-overlay Build vulkan-overlay-layer which displays Frames Per Second and other statistics
xa Enable the XA (X Acceleration) API for Gallium3D.
xvmc Enable the XvMC acceleration interface for the Gallium3D Video Layer.

openal

Flag Description
tests Build testing utilities

x264

Flag Description
interlaced enable interlaced encoding support, this can decrease encoding speed by up to 2%

media-video

obs-studio

Flag Description
imagemagick Use ImageMagick for image loading instead of FFmpeg.
luajit Build support for scripting via Luajit.
nvenc Enable NVENC encoding for nVidia video cards.
v4l2sink Enable the use of a virtual webcam.

vlc

Flag Description
a52
aa Enable ASCII filter
aom Enable experimental support for AV1 codec
aribsub Enable support for decoding ARIB STD-B24 subtitles
arm64
bidi
cddb
chromaprint Enable libchromaprint for Chromaprint based audio fingerprinter support
chromecast Enable experimental support for Google Chromecast
cpu_flags_arm_neon
cpu_flags_ppc_altivec
cpu_flags_x86_mmx
dav1d Enable support for <pkg>media-libs/dav1d</pkg> AV1 decoder
dc1394 Enable IIDC cameras support
decklink Enable decklink support
directx Enable Win32 DirectX, D3D11va and DxVA2 support
dts
dvbpsi Enable support for Mpeg-TS files (.ts, .m2ts, .mts) via <pkg>media-libs/libdvbpsi</pkg>
dvd
encode Enable streaming-output support and videolan manager to control multiple streams from within one instance
faad Enable AAC audio decoding library support via media-libs/faad2
ffmpeg
flac
fluidsynth Enable Fluidsynth MIDI software synthesis (with external sound fonts)
gcrypt Enable cryptography support via libgcrypt
gme Enable support for <pkg>media-libs/game-music-emu</pkg> for playing various video game music formats
gstreamer Enable GStreamer based decoding support (currently supports only video decoding)
ieee1394
libass
libav
libcaca
libnotify
libplacebo enable libplacebo (library based off mpv)
libsamplerate
libtar Uses libtar instead of the built-in tar reader for reading custom skins
libtiger Enable Ogg Kate subtitles rendering using libtiger
linsys Enable support for Linux Linear Systems Ltd. SDI and HD-SDI input cards
lirc
live Enable live555 streaming media support (client support for rtsp, preferred option)
macosx-notifications Enable Mac OS X notifications module (formerly growl)
macosx-qtkit Enable Mac OS X qtkit module: qtcapture (video) and qtsound (audio) module
mad
matroska Enable matroska support using reference libraries (fallback on other existing matroska support if disabled, i.e., matroska enabled FFmpeg)
mfx Add mfx (quicksync) support
modplug
mp3
mpeg Add libmpeg2 support for mpeg-1 and mpeg-2 video streams
musepack
neon
ogg
omxil Enable OpenMAX Integration Layer codec module
optimisememory Enable optimisation for memory rather than performance
opus Support opus decoding via libopus
oss Support oss (open source sound system)
postproc Enable image post-processing via libpostproc (part of FFmpeg)
projectm Enable the projectM visualization plugin
qt5
rdp
realrtsp Enable rtsp support using realrtsp
run-as-root Allows vlc to start for root. Don't enable this unless you have a very specific (e.g. embedded) need for it!
schroedinger Enable Dirac video support (an advanced royalty-free video compression format) via libschroedinger (high-speed implementation in C of the Dirac codec)
screen Enable screen capture support
sdl-image Enable sdl image video decoder (depends on sdl)
shine use the shine mp3 encoder
shout Enable libshout output
sid Adds support for playing C64 SID files through <pkg>media-libs/libsidplay</pkg>:2
skins Enable support for the skins2 interface
sndio Enable support for sndio
soxr Enable SoX Resampler support via <pkg>media-libs/soxr</pkg>
spatialaudio Enable support for the spatialaudio library
srt Enable support for Secure Reliable Transport (SRT) via <pkg>net-libs/srt</pkg>
taglib
theora
tremor Enable tremor, a fixed-point version of the Ogg Vorbis decoder
twolame Enable twolame support (MPEG Audio Layer 2 encoder)
upnp Enable support for the Intel SDK stack based UPnP discovery module instead of CyberLink
vcd add vcd and cd-da (audio cd) support
vnc
vorbis
vpx Enable the decoder(s) from the WebM VP8 / VP9 Codec SDK
wma-fixed Enable fixed point WMA decoder
x264
x265 Support X265 Encoder
zvbi Enable support for teletext subtitles via the zvbi library

net-im

telegram-cli

Flag Description
json

net-libs

libpsl

Flag Description
rpath

libtorrent-rasterbar

Flag Description
dht Enable DHT (distributed hash table) support

nodejs

Flag Description
bundled-ssl Use bundled OpenSSL instead of system-wide (EXPERIMENTAL)
inspector Enable V8 inspector
npm Enable NPM package manager
snapshot Enable snapshot creation for faster startup
system-icu
system-ssl

telegram-qt

Flag Description
generator Build protocol code generator
qml-import Enable compilation of qml import plugin
widgets-client Build a widgets-based client

net-misc

curl

Flag Description
adns Add support for asynchronous DNS resolution via c-ares library
alt-svc Alternative Service HTTP header support
brotli Brotli content encoding support
cookies Cookies support
curl_ssl_gnutls
curl_ssl_libressl
curl_ssl_mbedtls Use mbed TLS (previously PolarSSL)
curl_ssl_nss
curl_ssl_openssl
curl_ssl_winssl
curldebug curl debug memory tracking
dict DICT protocol
digest Digest access authentication
elibc_Winnt
file file
fish support fish shell
ftps FTPS
gnutls
gopher Gopher
hsts
http2 HTTP/2 - a major revision of the HTTP network protocol
imap
imaps IMAPS
largefile Support large files (2GB+)
ldaps LDAPS
libcurl-option libcurl C code generation support
libgcc Use libgcc when linking
manual Built-in manual
mbedtls
metalink metalink (.meta4, .metalink files)
nghttp3
nss
ntlm-wb NTLM delegation to winbind's ntlm_auth helper
openssl-auto-load-config Automatic loading of OpenSSL configuration
pop3 POP3 (Post Office Protocol version 3)
pop3s POP3S
progress-meter have a Progress meter
proxy Proxy support
psl PSL (Publix Suffix List) - avoids privacy-leaking "supercookies"
quiche Add quiche library that supports QUIC and http3
rt Add dependency on -lrt
rtmp RTMP (Real-Time Messaging Protocol) Streaming Media
sambas SMBS/CIFS
shared-libs build shared libraries
smtp SMTP (Simple Mail Transfer Protocol)
smtps SMTPS
ssh-old libssh support for (SCP, SFTP)
ssh2 libssh2 support for (SCP, SFTP)
symbol-hiding Hide library internal symbols ("-fvisibility=hidden"; https://gcc.gnu.org/wiki/Visibility)
telnet telnet
tftp TFTP (Trivial File Transfer Protocol)
tls-srp TLS-SRP authentication
unix-sockets Unix domain sockets
versioned-symbols Versioned symbols in shared library (https://gcc.gnu.org/wiki/SymbolVersioning)
winssl
zsh support zsh shell

iputils

Flag Description
arping Build and install `arping` -- tool for sending ARP requests to peers (see also <pkg>net-analyzer/arping</pkg>)
clockdiff Build and install clockdiff -- tool for comparing clocks via ICMP packets
crypto_gcrypt Use <pkg>dev-libs/libgcrypt</pkg> for crypto support
crypto_kernel Use kernel Crypto API for crypto support
crypto_nettle Use <pkg>dev-libs/nettle</pkg> for crypto support
crypto_openssl Use <pkg>dev-libs/openssl</pkg> for crypto support
html Build HTML versions of manpages (requires extra dependencies)
ninfod Build and install `ninfod`
ninfod-messages Enable debug messages in `ninfod`
ping Build and install `ping`
rarpd Build and install rarpd -- server for handling RARP (reverse ARP) requests; generally only used by old systems
rdisc Build and install rdisc -- server for the client side of the ICMP router discover protocol
rdisc-server Build and install `rdisc-server`
tftpd Build and install tftpd -- server for the Trivial File Transfer Protocol (see also <pkg>net-ftp/tftp-hpa</pkg>)
tracepath Build and install tracepath -- tool for tracing network paths for discovering MTU values
traceroute6 Build and install traceroute6 -- tool for tracing network paths (see also <pkg>net-analyzer/traceroute</pkg>)

sys-apps

file

Flag Description
seccomp
split-usr

hwloc

Flag Description
gl Enable GL display device discovery (NVCtrl)
numa Add support for numa memory allocation
pci Enable PCI device discovery using libpci

kmod

Flag Description
pkcs7

portage

Flag Description
aix use aix utils
apidoc Build html API documentation with sphinx-apidoc.
changelog patch support for viewing changelogs back in, changing the shorthand to make it upstream config compatible
gentoo-dev Enable features required for Gentoo ebuild development.
ipc Use inter-process communication between portage and running ebuilds.
native-extensions Compiles native "C" extensions (speedups, instead of using python backup code). Currently includes libc-locales. This should only be temporarily disabled for some bootstrapping operations. Cross-compilation is not supported.
pax use pax utils
rsync support rsync repositories
rsync-verify Enable full-tree cryptographic verification of Gentoo repository rsync checkouts using <pkg>app-portage/gemato</pkg>.
sandbox use sandbox

sandbox

Flag Description
ptrace Use ptrace functions

world

Flag Description
amd Add support for amd cpus
anaconda One of your chosen options requires anaconda which has a large number of python development features, you will need to install it from inside sublime text. you can turn off linting with {"anaconda_linting": false}
ath9k Install the ath9k driver for 802.11n qualcomm/atheros NICs
bfq Install the bfq scheduler
bmq Install the bmq scheduler
broadcom add support for broadcom devices
browser install a graphical web browser
btrfs install <pkg>sys-fs/btrfs-progs</pkg> for btrfs, a recently matured snapshotting copy-on-write file system, and the relevant kernel drivers
cad install <pkg>media-gfx/solvespace</pkg> for fully parametric 2d and 3d cad that's simple, easy to use and exports to a wide variety of formats
chrome install chromium/chrome of some variety
composite install <pkg>x11-misc/picom</pkg> to enable compositing, a way to render extra effects and transparency in windows
composite-gui install <pkg>lxqt-base/compton-conf</pkg>, a gui to configure compton
context-background
context-bluetooth
context-compress
context-email
context-resize
copy-notification require that the file manager creates a notification when a copy operation is complete
dev install <pkg>app-portage/repoman</pkg>, a tool designed to aid in managing overlays
dev-java install <pkg>dev-util/eclipse-sdk-bin</pkg>, an ide designed for java
discord install discord, an online messenger and games store
dolphin install <pkg>kde-apps/dolphin</pkg>, the tabbed file manager of kde. This may not be the best file manager for newcomers
efi ensure efi support is built, most modern systems need this
exfat Install drivers to work with exfat partitions
ext2 Install drivers to work with ext2 partitions
extended-glyphs install <pkg>media-fonts/noto</pkg>, a font that supports a lot of glyphs
f2fs Install drivers to work with f2fs partitions
fat ensure fat filesystem support is built, in many cases this should not be the only filesystem
firefox install <pkg>www-client/firefox</pkg>, this is quicker to compile from source, and has better privacy options
flash ensure the <pkg>www-plugins/adobe-flash</pkg> plugin is installed. flash is a dying platform, however there are historic games and animations made with it
fluxbox use <pkg>x11-wm/fluxbox</pkg> as the window manager of choice. typically this has medium performance and can even be used as a full desktop solution if so desired
fslint install <pkg>app-misc/fslint</pkg>, this is a useful tool for finding duplicate files, empty directories and other such things to help keep a system clean
fvwm use <pkg>x11-wm/fvwm</pkg> as the window manager of choice. it has great performance and even has its own desktop environment, however it is very difficult to set up. and is poor at integration.
gnomekeyring-admin install <pkg>app-crypt/seahorse</pkg> in order to manage gnome keyring with a gui
gzip compress the kernel with gzip
hygon Add support for hygon cpus
image-resolution require that the file manager is able to display an image resolution
index install mlocate to allow indexing which helps make file searches faster
indicate-transparency require that the file manager indicates an image's transparency by putting a checkerboard behind it
inkscape install <pkg>media-gfx/inkscape</pkg>, a powerful svg and pdf editor
intel Add support for intel cpus
irc install <pkg>net-irc/kvirc</pkg> in order to use irc. this is often a preferred way to get volunteer support with issues or make quick queries
ivybridge Add support for ivybridge cpus
java-dev
java-ide install <pkg>dev-util/eclipse-sdk-bin</pkg>, a popular java ide
jpeg-thumbnail require that the file manager creates thumbnails for svg files
js-lint Add support for linting javascript in sublime-text using
kyber Install the kyber scheduler
latex install <pkg>app-office/lyx</pkg>, an editor for latex that's great for beginners
logisim install <pkg>sci-electronics/logisim-evolution-holy-cross</pkg>, a fork of a fork of logisom that performs well
lzo compress the kernel with lzo, this usually boots fastest
mail-client install <pkg>mail-client/mailspring</pkg>, a partially open source mail client
mips-emulate install <pkg>app-emulation/mars-mips</pkg>, a MIPS assembly emulator
network-tray install <pkg>gnome-extra/nm-applet</pkg>, a universal system tray that helps with wireless networks
odt install <pkg>app-office/libreoffice</pkg> to handle odt files and convert between them
odt-convert install <pkg>dev-tex/tex4ht</pkg> to convert latex files to odt, which can subsequently be reviewed and converted to docx with libreoffice
odt-thumbnail require that the file manager creates thumbnails for svg files
openbox use openbox as the window manager of choice. openbox is more widely supported including having its own configuration gui, at the cost of performance
openrc Add support for the openrc init system
overlay install <pkg>app-portage/layman</pkg> to handle overlays, not using overlays is generally not supported
pantheon-files install <pkg>pantheon-base/pantheon-files</pkg>, the tabbed file manager of elementary os
parted install <pkg>sys-block/gparted</pkg> to handle partitions
pcmanfm-qt install <pkg>x11-misc/pcmanfm-qt</pkg>, the tabbed file manager of lxqt
pdf
pdf-edit require that the system can edit pdf files
pdf-view require that the system can view pdf files
pdf-view-accurate install <pkg>app-text/mupdf</pkg> to view high quality pdf renders
php-ide install <pkg>dev-php/phpstorm</pkg>, a well known non-free php ide
png-thumbnail require that the file manager creates thumbnails for png files
progress-icon require that the file manager shows its progress bar on the icon
remote-desktop install <pkg>net-misc/anydesk</pkg> to enable remote desktop functionality
secondlife install <pkg>games-simulation/firestorm-bin</pkg> as a secondlife viewer
secure Various security options that while more secure reduce performance and make things more difficult
spreadsheet install <pkg>app-office/gnumeric</pkg> to handle spreadsheets
sql install <pkg>dev-db/mariadb</pkg> to handle databases
steam install <pkg>games-util/steam-launcher</pkg>, a software distribution platform with one of the largest game catalogues and proton, a built in version of wine
sublime install <pkg>app-editors/sublime-text</pkg> as your gui-based text editor. many extra features will require you install plugins, these will require that you install package control. note that sublime text is not free and once you are satisfied in your evaluation of the product you should buy a licence, although you are free to evaluate it as much as required.
sublimelinter One of your chosen options requires sublimelinter which is a large linting framework, you will need to install it from inside sublime text
svg-edit require that the system can edit svg files
svg-thumbnail require that the file manager creates thumbnails for svg files
system-flake8 require that your python linting uses locally installed flake8. you will need to install SublimeLinter-flake8. make sure to disable anaconda linting.
system-pylint require that your python linting uses locally installed pylint. you will need to install SublimeLinter-pylint. make sure to disable anaconda linting.
terminal-fast install <pkg>x11-terms/kitty</pkg>, a terminal emulator that utilises hardware acceleration to run fast while using theoretically less resources
text-editor-color-highlight require that your text editor has colour highlighting and thus install <pkg>app-editors/sublime-text</pkg> to satisfy that. you must install Color Highlight to enable it.
text-editor-js-complete require that your text editor has javascript code completion and thus install <pkg>app-editors/sublime-text</pkg> to satisfy that. you must install JavaScript Enhancements to enable it as well as the npm package flow.
text-editor-js-lint require that your text editor has javascript linting and thus install <pkg>app-editors/sublime-text</pkg> to satisfy that. you must install SublimeLinter contib standard to enable it as well as the npm package standard.
text-editor-php-lint require that your text editor has php linting and thus install <pkg>app-editors/sublime-text</pkg> and <pkg>dev-lang/php</pkg> to satisfy that. you must install SublimeLinter-php to enable it.
text-editor-py-complete require that your text editor has python code completion and thus install <pkg>app-editors/sublime-text</pkg> to satisfy that.
text-editor-py-lint
threads-16 Add support for a 16 threaded system
threads-4 Add support for a 4 threaded system
threads-512 Add support for a 512 threaded system
uefi Add support for uefi
viewfont use the gui of <pkg>media-gfx/fontforge</pkg> to view all the glyphs a font offers
xeon Add support for xeon cpus
xfs ensure xfs filesystem support is built, xfs has some of the best performance on kernel 5+ for SSDs
xz compress the kernel with xz
yandex-disk Install <pkg>net-misc/yandex-disk</pkg>, the official yandex disk client
zhaoxin Add support for zhaoxin cpus

sys-devel

binutils

Flag Description
default-gold Set ld to point to ld.gold instead of ld.bfd
gold Build ld.gold linker
multitarget Adds support to binutils for cross compiling (does not work with gas)

gcc

Flag Description
clang Add patches to allow lld to be used as the linker
fixed-point Enable fixed-point arithmetic support for MIPS targets in gcc (Warning: significantly increases compile time!)
go Build the GCC Go language frontend.
graphite Add support for the framework for loop optimizations based on a polyhedral intermediate representation
jit Enable libgccjit so other applications can embed gcc for Just-In-Time compilation. This will slow down the compiler a bit as it forces all of the toolchain to be shared libs.
libssp Build SSP support into a dedicated library rather than use the code in the C library (DO NOT ENABLE THIS IF YOU DON'T KNOW WHAT IT DOES)
mpx Enable support for Intel Memory Protection Extensions (MPX)
objc Build support for the Objective C code language
objc++ Build support for the Objective C++ language
objc-gc Build support for the Objective C code language Garbage Collector
regression-test Run the testsuite and install the results (requires FEATURES=test)
sanitize Build support for various sanitizer functions (ASAN/TSAN/etc...)
ssp Build packages with stack smashing protector on by default
vtv Build support for virtual table verification (a C++ hardening feature)

sys-fs

ntfs3g

Flag Description
acl POSIX ACL support
device-default-io-ops Install default IO ops
external-fuse Use <pkg>sys-fs/fuse</pkg> library instead of internal one. Must be disabled for unprivileged mounting to work.
hd Use Windows compliant disk geometry, requires libhd from <pkg>sys-apps/hwinfo</pkg>
ldscript Use ldscript instead of .so symlink
library Install libntfs-3g
mount-helper Install mount helper
mtab Use /etc/mtab
ntfs-3g Enable the ntfs-3g FUSE driver
ntfsprogs Include internal version of ntfsprogs utilities
pedantic Enable compiler's pedantic mode
quarantined Install quarantined (non functional) ntfsprogs utilities
really-static Create fully static binaries
uuid Generate DCE compliant UUIDs, requires <pkg>sys-libs/libuuid</pkg>

sys-kernel

gentoo-sources

Flag Description
experimental Apply experimental patches; for more information, see "https://wiki.gentoo.org/wiki/Project:Kernel/Experimental".
long-arg enable longer commandline arguments

sys-process

htop

Flag Description
cgroup Enable cgroup support
delayacct Delay accounting
hwloc enable <pkg>sys-apps/hwloc</pkg> support for CPU affinity
linux-affinity Enable Linux sched_setaffinity() and sched_getaffinity() for affinity support, disables hwloc
openvz Enable openvz support
taskstats Enable per-task IO Stats (taskstats kernel support required)
vserver Enable vserver support

lsof

Flag Description
rpc support looking up RPC service info

virtual

cblas

Flag Description
eselect-ldso Enable runtime library switching by eselect and ld.so.
int64

linux-sources

Flag Description
firmware Install linux kernel firmware

mime-types

Flag Description
gentoo Install official mime-types
mailcap Install mailcap mime-types, these are used in arch linux

wine

Flag Description
abi_x86_32
abi_x86_64
proton use steam's proton to provide the wine requirement
staging Enable Wine-Staging's Patchset

www-client

vimb

Flag Description
gtk3

www-plugins

freshplayerplugin

Flag Description
gles2-only