There is only one cpio ebuild available (2.6-r2), and it is unstable for all architectures. Reproducible: Always Steps to Reproduce: 1. 2. 3.
grep KEYWORDS cpio-2.6-r2.ebuild KEYWORDS="alpha amd64 arm hppa ia64 mips ppc ppc64 ppc-macos s390 sh sparc x86"