EIP-8163: Reserve EXTENSION (0xae) Opcode

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Discussion topic for Add EIP: Reserve `EXTENSION (0xae)` opcode by pdobacz · Pull Request #11327 · ethereum/EIPs · GitHub Update Log 2026-02-17: initial draft External Reviews None as of 2026-02-17. Outstanding Issues None as of 2026-02-17. Summary (from EIP text:) The EIP reserves an opcode `EXTENSION (0xae)` which will be guaranteed to not become a valid opcode on Ethereum L1 EVM, but which will be available to be used in other EVMs as a prefix to encode extension instructions. By setting aside a single opcode and agreeing that it will never become a valid instruction on Ethereum L1 EVM, we open up to extensions which can be implemented on other EVM chains. If these extensions prove out to be successful outside of Ethereum L1, then they can be back-ported into Ethereum L1 EVM, to the benefit of the entire EVM ecosystem. The extension opcode is designed in such a way to not only have **no impact** on Ethereum L1 EVM behavior, but also to not require any Ethereum Execution Layer Client modifications relevant to consensus. Prior art MIP-7: Extension opcodes , original Monad Improvement Proposal 1 post - 1 participant Read full topic