Binpkgs generated by user
The binary packages generated by user can have architecture-specific optimizations because they are generated after they were compiled by the host Portage installation.
In addition binpkgs are generated from ebuilds so if there is a USE flag incompatibility on the consumer system then the binpkg will not be installed on the host and Portage will fall back to from-source compilation.
XPAK had many issues and is getting superseded by the GPKG format. Beware of upcoming GPKG transition and if you must use XPAKs then you should explicitly enable it in your system’s Portage configuration.
To host a binary package distribution server see the Binary package guide on the Gentoo wiki.
Bin packages in a repository
Binary packages in
::gentoo (the official Gentoo repository) have the
Those packages might have USE flags but generally they are very limited in case of customizations or code optimizations because they were compiled either by a Gentoo developer or by a given package upstream maintainer (or their CI/CD system).
Those packages land in
::gentoo mostly because it is too hard (or even impossible) to compile them natively by Portage. Most of the time those packages use very complicated build systems or do not play nice with network sandbox like (e.g. Scala-based projects) or use very large frameworks/libraries like (e.g.
They can also be added to the repository because they are very
desirable either by normal users (e.g. www-client/firefox-bin) or for (from-source) package
bootstrapping purposes (e.g. dev-java/openjdk-bin). Such packages are sometimes generated from the regular source packages inside
::gentoo and later repackaged.