USE flags

Flag priority is configured with USE_ORDER and has a default order of priority:

1. The USE parameter in emerge.
2. Package-specific flags in package.use.
3. Global flags in make.conf.
4. Eselected Gentoo profile defaults.
5. Emerged package defaults.
6. Ebuild repository defaults.
7. Environment-specific /etc/env.d (rarely used).

The ~amd package keyword is a convention for WIP packages.

Unstable packages should always be filled in package.accept_keywords for Portage to emerge them.

The CPU architecture is auto-detected with -march=native in COMMON_FLAGS during package compilation.