Profiles use.mask File

The use.mask file can be used to mark USE flags as unavailable on a particular profile. This can be useful for various reasons:

Note that use.mask is a per-flag thing, not per package's use of a given flag. This is one of the reasons that USE flags must have a specific well defined purpose.

Updates to use.mask should be handled via the relevant arch team.

See noblah USE Flags for more discussion.