elisregina ~ # emerge =darcs-1.0.4
Calculating dependencies   
!!! All ebuilds that could satisfy "=darcs-1.0.4" have been masked.
!!! One of the following masked packages is required to complete your request:
- dev-util/darcs-1.0.4 (masked by: ~x86 keyword)

For more information, see MASKED PACKAGES section in the emerge man page or 
refer to the Gentoo Handbook.