Patents have a 20-year lifespan so the common x86_32 patents must have already expired. As for x86_64, the patents would expire in either 2020 or 2023 dependin

Patents have a 20-year lifespan so the common x86_32 patents must have already expired. As for x86_64, the patents would expire in either 2020 or 2023 depending on if you count from the first published documentation or from the first shipping CPU (IANAL). Of course that is only the baseline ISA (and SSE2). The future extensions (SSE3+/FMA/AVX and AES-NI/RDRAND/...) would not yet be patent-free but most software is really just compiled against the baseline. Apple managed to split x86_64 into a sub-architecture x86_64h for post-Haswell, but broadly speaking, nobody else has: https://fedoraproject.org/wiki/Changes/x86-64_micro-architecture_update https://fedoraproject.org/wiki/Changes/x86-64_micro-architec...