Masked vs ~arch

In Gentoo there are two ways to protect the user from packages that remain untested.

Masked packages cannot be installed from the command line (using emerge) without first unmasking them. These packages are usually masked for a very good reason, e.g. they are broken or break something else. The first idea would be to remove the corresponding line from /usr/portage/profiles/package.mask but this file is overwritten whenever emerge rsync is executed. As of portage-2.0.50 superusers can unmask packages by adding an appropriate line to /etc/portage/package.unmask.

NOTE: Superusers can also mask packages in /etc/portage/packages.mask.

Another class of packages consists of stable packages that have not undergone extensive testing with regard to Gentoo. Though they can still be installed by using emerge. Gentoo disinguishes between tested packages belonging to arch (e.g. x86 or ppc) and stable but untested packages belonging to ~arch (e.g. ~x86 or ~ppc). This assignment of keywords (arch or ~arch) can be overridden in two ways:

1. Per execution of emerge: The following command does not only override the keywords for the specified package but also for all dependencies that need to be pulled in: ACCEPT_KEYWORDS="~ARCH" emerge PACKAGE.

2. Per package: As of portage-2.0.50 the superuser can override the keywords specified in the ebuild by appending lines to /etc/portage/package.keywords consisting of a package pattern followed by the new keywords:

  app-portage/gentoolkit ~x86
  dev-util/subversion ~x86

WARNING: Do not use /usr/portage/profiles/package.{,un}mask because they are overwritten by emerge rsync. Modifying /etc/portage/profiles/package.{,un}mask also fails because /etc/portage/profiles is a symlink /usr/portage/profiles.