If I install texlive 2012 from DVD, biblatex is will be installed. But currently, biblatex is mark as unstable is not installed.
(In reply to Yichao Zhou from comment #0) > If I install texlive 2012 from DVD, biblatex is will be installed. > > But currently, biblatex is mark as unstable is not installed. Currently only texlive 2017 is stable (or even in the tree; see <https://packages.gentoo.org/packages/app-text/texlive-core>). So please try that and report back.
It is still the same situation with recent texlive tested by asking our chatbot wilikins !rdep dev-tex/biblatex I think dev-tex/biblatex should not be a hard RDEPEND for app-text/texlive, because many users can work without it. For example if you need app-text/texlive as renderer for TeX support in Inkscape.
*** Bug 746707 has been marked as a duplicate of this bug. ***
biblatex will be pulled in once the 'extra' USE flag is enabled on app-text/texlive via texlive[extra] → bibtexextra → biblatex