The C++ and Rust EVMs are separate luxd plugins. The host spawns every VM with
VM_TRANSPORT=zap (node/vms/rpcchainvm/factory.go) and the cevm binary is
exercised that way cross-process today. Choosing an EVM is choosing which plugin
binary runs -- not a switch inside the Go EVM.
This tree carried a second mechanism for the same choice: an in-process cgo
bridge that linked C++ into the Go binary behind -tags cevm/revm, with a
per-transaction executor registry, an evm_setBackend RPC to flip between
backends at runtime, a resident-store config knob, and a startup log naming the
chosen backend. Its executor returned nil, nil; its tagged build did not compile
(cevm_resident_store.go referenced symbols cevmbridge never defined); and no
build produced a binary that used it. 3,961 lines, gone.
What stays is what the Go EVM actually has: the BlockExecutor seam and
Block-STM behind it (blockstm.go), and the GPU accelerator seam with its
darwin/cgo bridge into luxfi/gpu (gpu_bridge.go). The state processor consults
both and falls through to sequential execution when neither is registered.
Note for the record: nothing in the shipped binary registers a BlockExecutor,
so blocks run sequentially on the Go interpreter. The removed startup log said
"Block-STM across all cores"; it was not describing this binary. Wiring
Block-STM into the production path changes consensus execution and is a
separate decision, made deliberately, with a parity gate.
Co-authored-by: Hanzo Dev <[email protected]>
zeekayandHanzo Dev