Global USE flags

Flag Description Packages
debug Enable memory debugging. 5
discord Enable Discord Rich Presence 2
gtk 2
l10n_ 2
qt6 2
selinux 2
systray Install <pkg>dev-libs/libappindicator</pkg> to enable systray 2

Category USE flags

app-backup

Flag Description Packages
hardened Enables GCC runtime fortification 2
zlib Enables compression 2

app-emulation

Flag Description Packages
abi_x86_32 2

sys-kernel

Flag Description Packages
plymouth Enables support for <pkg>sys-boot/plymouth</pkg> in the initramfs (but does not mandate its use). 3

x11-themes

Flag Description Packages
gtk2 GTK2 Support 2
icons Install icon theme 2

Local USE flags

app-backup

urbackup-client

Flag Description
gui Enables building the wxWidgets GUI

urbackup-server

Flag Description
crypt Enables encrypted transfers and thus internet backups
fuse Enables mounting VHD containers via FUSE
mail Enables email notifications

app-cdr

dvdisaster

Flag Description
nls

app-emulation

dxvk-nvapi

Flag Description
crossdev-mingw Use <pkg>sys-devel/crossdev</pkg> for the toolchain rather than <pkg>dev-util/mingw64-toolchain</pkg> (requires manual setting up)

app-portage

genup

Flag Description
buildkernel Enable support for buildkernel (include buildkernel dependency).
emtee Enable support for emtee (include emtee dependency).

dev-util

electron

Flag Description
X
bluetooth Enable Bluetooth. Disabling bluetooth does break WebAuthn. Could also break something else. Improved patch is welcome.
clang Use Clang compiler instead of GCC
cpu_flags_arm_neon
cpu_flags_ppc_vsx3
cups
custom-cflags
dev-dependencies Keep Electron's devDependencies. This makes them available in node_modules. For example "asar" utility is one of them.
gtk4 Build with GTK4 headers
hangouts Enable support for Google Hangouts features such as screen sharing
hevc Enable HEVC decoding support. Should work with system-ffmpeg, but might require additional patching for the built-in one.
js-type-check Enable JavaScript type-checking for Chrome's web technology-based UI. Requires Java.
kerberos
libcxx Use bundled C++ Standard Library (libc++)
nvidia Use libXNVCtrl library from <pkg>x11-drivers/nvidia-drivers</pkg> instead of the bundled one
optimize-thinlto Whether to enable ThinLTO optimizations. Turning ThinLTO optimizations on can substantially increase link time and binary size, but they generally also make binaries a fair bit faster.
optimize-webui Optimize parts of Chromium's UI written with web technologies (HTML/CSS/JS) for runtime performance purposes. This does more work at compile time for speed benefits at runtime.
pax-kernel Allow building on a PaX-enabled kernel
pgo Enable PGO. Requires bundled binary profile data in sources tree. Often requires masked/testing llvm.
pic Disable optimized assembly code that is not PIC friendly
proprietary-codecs Enable proprietary codecs like H.264, MP3
pulseaudio
screencast Enable support for remote desktop and screen cast using <pkg>media-video/pipewire</pkg>
suid Build the SUID sandbox, which is only needed on CONFIG_USER_NS=n kernels
system-
system-abseil-cpp Use the system <pkg>dev-cpp/abseil-cpp</pkg> instead of the bundled one
system-av1 Use the system <pkg>media-libs/libaom</pkg> and <pkg>media-libs/dav1d</pkg> instead of the bundled ones
system-brotli Use the system <pkg>app-arch/brotli</pkg> instead of the bundled one
system-crc32c Use the system <pkg>dev-libs/crc32c</pkg> instead of the bundled one
system-double-conversion Use the system <pkg>dev-libs/double-conversion</pkg> instead of the bundled one
system-ffmpeg Use the system <pkg>media-video/ffmpeg</pkg> instead of the bundled one
system-harfbuzz Use the system <pkg>media-libs/harfbuzz</pkg> instead of the bundled one
system-icu Use the system <pkg>dev-libs/icu</pkg> instead of the bundled one
system-jsoncpp Use the system <pkg>dev-libs/jsoncpp</pkg> instead of the bundled one
system-libevent Use the system <pkg>dev-libs/libevent</pkg> instead of the bundled one
system-libusb Use the system <pkg>dev-libs/libusb</pkg> instead of the bundled one
system-libvpx Use the system <pkg>media-libs/libvpx</pkg> instead of the bundled one
system-openh264 Use the system <pkg>media-libs/openh264</pkg> instead of the bundled one. If disabled, it will restrict USE=bindist.
system-openjpeg Use the system-wide <pkg>media-libs/openjpeg</pkg> instead of the bundled one. OpenJPEG use are exclusively for Chromium's PDF viewer.
system-png Use system libpng instead of the bundled one
system-re2 Use the system-wide <pkg>dev-libs/re2</pkg> instead of the bundled one
system-snappy Use the system-wide <pkg>app-arch/snappy</pkg> instead of the bundled one
system-woff2 Use the system <pkg>media-libs/woff2</pkg> instead of the bundled one
system-zstd Use the system <pkg>app-arch/zstd</pkg> instead of the bundled one
thinlto Build with ThinLTO support. LTO (Link Time Optimization) achieves better runtime performance through whole-program analysis and cross-module optimization (highly recommended).
ungoogled Apply ungoogled-chromium modifications to chromium sources (electron sources are not modified be it better or worse). Might break electron apps or electron itself!
vaapi
wayland

games-emulation

citron-neo

Flag Description
camera Enable camera support through dev-qt/qtmultimedia
cubeb Enable the cubeb audio backend
llvm Enable the LLVM backend for disassembly and symbol demangling
room Compile the dedicated room executable
test
usb Enable the LibUSB controller backend
web-applet Enable the custom web applet frontend through dev-qt/qtwebengine
web-service Enable multiplayer support

games-fps

gzdoom

Flag Description
gles2 Enable GLES2 backend
non-free Enable non-free components
openmp
swr Enable software renderer
telemetry
vulkan Enable Vulkan support

gui-wm

gamescope

Flag Description
avif
libei Enable emulated input using <pkg>dev-libs/libei</pkg>
pipewire Enable screen capture via PipeWire
sdl
wsi-layer Enable the WSI layer (required for HDR)

media-libs

alvr

Flag Description
video_cards_nvidia

media-tv

jellyfin-mpv-shim

Flag Description
display-mirroring Enable display-mirroring
shaders Install MPV shader pack

net-nntp

ngpost

Flag Description
7z Install <pkg>app-arch/p7zip</pkg>
par2 Install <pkg>app-arch/par2cmdline</pkg>
rar Install <pkg>app-arch/rar</pkg>

sys-kernel

genkernel-next

Flag Description
cryptsetup Enable support for Luks disk enrcyption using <pkg>sys-fs/cryptsetup</pkg>
dmraid Enable support for DMRAID (include dmraid dependency)
gpg Enable support for GPG (include gnupg dependency)
iscsi Enable support for open-iscsi (include open-iscsi dependency)
mdadm Enable support for mdadm (include mdadm dependency)

sys-power

RyzenAdj

Flag Description
ryzen-smu Use <pkg>app-admin/ryzen_smu</pkg> kernel driver instead of <pkg>sys-apps/pciutils</pkg>.

sys-process

nohang

Flag Description
systemd

virtual

linux-sources

Flag Description
firmware Install linux kernel firmware

x11-themes

gruvbox-material-gtk-theme

Flag Description
hidpi Install HIDPI version