This ebuild is not masked for amd64 but fails to compile. !!! ERROR: dev-libs/gmp-4.1.2 failed. !!! Function src_compile, Line 37, Exitcode 2 !!! emake failed Tested on 2 separate systems. Kernel 2.6.2. dev-libs/gmp-4.1-r1 fails too.
http://swox.com/list-archives/gmp-discuss/2003-July/000684.html fixes the problem
The patch was added to 4.1.2 on 19 Oct 2003. Please reopen bug with build log and emerge info if the problem still exist.