app-portage/hackport
Hackage and Portage integration tool
USE Flags
profile
Global: Adds support for software performance analysis (will likely vary from ebuild to ebuild)
+threads
* This flag is undocumented *
test
Global: Workaround to pull in packages needed to run with FEATURES=test. Portage-2.1.2 handles this internally, so don't set it in make.conf/package.use anymore