zeekayandHanzo Dev
0121536b30
ROOT CAUSE of the C-Chain bootstrap ancestry-descent stall: ParseBlock was STATEFUL.
BlockGasCost is NOT in the RLP block — it is DERIVED from the parent header. UnmarshalBlock
computed it via vm.blockChain.GetHeaderByHash(parent), and SyntacticVerify REQUIRED it non-nil
(errNilBlockGasCostEVM). For a bootstrap descent parsing ancestry blocks AHEAD of the accepted
height the parent is not present, so every such block failed to parse — masked by the ZAP
errorToZAP mapping as the misleading "malformed block id (does not connect to accepted chain)".
The Lux bootstrapper indexes the whole fetched batch by (id,height,parent) up front, so it could
not index the ancestry, never found the frontier tip in the batch, and re-requested forever ->
ErrStalled. Confirmed on devnet: "syntactic block verification failed: nil blockGasCost is
invalid after EVM activation".
FIX — decomplect parse from verify (matches upstream avalanchego coreth: parse decodes, Verify
enforces connectivity):
- block.go: new ensureBlockGasCost() fills BlockGasCost from the parent header WHEN PRESENT
(SetHeaderExtra is hash-keyed, so it persists for a block first parsed while its parent was
absent). Best-effort at parse; authoritative at Verify (AcceptBootstrapBlock calls blk.Verify
only after the contiguity gate height==finalized+1, so the parent is ACCEPTED/present).
- block_verification.go: SyntacticVerify no longer requires BlockGasCost (stateless,
block-intrinsic checks only); keeps the uint64 sanity check when it IS set.
- vm.go UnmarshalBlock: replace the inline parent-lookup with block.ensureBlockGasCost().
SAFETY (parse != accept): parse only decodes + stateless syntactic checks; no non-connecting or
gas-cost-invalid block can be ACCEPTED just because it now parses. Verify/Accept
(InsertBlockManual -> consensus/dummy header verification) recomputes the expected BlockGasCost
from the (present) parent and rejects a mismatch; the bootstrap contiguity gate accepts blocks
oldest-first (parent finalized). A wrong-hash block is rejected off-path by the content-addressed
descent. BlockGasCost is not in the block hash -> no malleability.
evm plugin/evm tests pass.
Co-authored-by: Hanzo Dev <[email protected]>
Lux EVM
Lux is a network composed of multiple blockchains. Each blockchain is an instance of a Virtual Machine (VM), much like an object in an object-oriented language is an instance of a class. That is, the VM defines the behavior of the blockchain.
Lux EVM is the unified Virtual Machine (VM) that powers both the C-Chain and L1/L2 Subnet EVM chains. This package consolidates the former Coreth (C-Chain) and Subnet EVM codebases into a single implementation.
Note
: The
github.com/luxfi/corethrepository has been deprecated and merged here. See the migration guide below.
This chain implements the Ethereum Virtual Machine and supports Solidity smart contracts as well as most other Ethereum client functionality.
Building
The Subnet EVM runs in a separate process from the main Luxd process and communicates with it over a local ZAP-native connection (LP-186 wire schema, no protobuf, no gRPC).
Luxd Compatibility
[v0.7.0] [email protected] (Protocol Version: 38)
[v0.7.1] [email protected] (Protocol Version: 39)
[v0.7.2] [email protected]/1.13.0-testnet (Protocol Version: 39)
[v0.7.3] [email protected]/1.13.0 (Protocol Version: 39)
[v0.7.4] [email protected] (Protocol Version: 40)
[v0.7.5] [email protected] (Protocol Version: 41)
[v0.7.6] [email protected] (Protocol Version: 42)
[v0.7.7] [email protected] (Protocol Version: 42)
API
The Subnet EVM supports the following API namespaces:
ethpersonaltxpooldebug
Only the eth namespace is enabled by default.
Full documentation for the C-Chain's API can be found here.
Compatibility
The Subnet EVM is compatible with almost all Ethereum tooling, including Remix, Metamask, and Foundry.
C-Chain vs Subnet EVM Mode
This unified EVM package supports both modes:
C-Chain Mode (Primary Network):
- Atomic transactions for cross-chain transfers (X-Chain ↔ C-Chain)
- Shared memory integration
- Primary network consensus
Subnet EVM Mode (L1/L2 Subnets):
- Configurable fees and gas limits in genesis
- Simplified hardfork configuration
- No atomic transactions (cross-chain via Warp messaging)
Migrating from Coreth
If you were using github.com/luxfi/coreth, update your imports:
// Before
import "github.com/luxfi/coreth/core"
// After
import "github.com/luxfi/evm/core"
All coreth functionality is preserved in this package.
Block Format
To support these changes, there have been a number of changes to the EVM block format compared to what exists on the C-Chain and Ethereum. Here we list the changes to the block format as compared to Ethereum.
Block Header
BaseFee: Added by EIP-1559 to represent the base fee of the block (present in Ethereum as of EIP-1559)BlockGasCost: surcharge for producing a block faster than the target rate
Create an EVM Subnet on a Local Network
Clone EVM
First install Go 1.23.9 or later. Follow the instructions here. You can verify by running go version.
Set $GOPATH environment variable properly for Go to look for Go Workspaces. Please read this for details. You can verify by running echo $GOPATH.
As a few software will be installed into $GOPATH/bin, please make sure that $GOPATH/bin is in your $PATH, otherwise, you may get error running the commands below.
Download the evm repository into your $GOPATH:
cd $GOPATH
mkdir -p src/github.com/luxfi
cd src/github.com/luxfi
git clone [email protected]:luxfi/evm.git
cd evm
This will clone and checkout to master branch.
Run Local Network
To run a local network, it is recommended to use the lux-cli to set up an instance of EVM on a local Lux Network.
There are two options when using the Lux-CLI:
- Use an official EVM release: https://docs.lux.network/subnets/build-first-subnet
- Build and deploy a locally built (and optionally modified) version of EVM: https://docs.lux.network/subnets/create-custom-subnet
Releasing
You can refer to the docs/releasing/README.md file for the release process.
Plugin Runtime Env Vars
The EVM plugin reads its rpcchainvm handshake address and transport from the
unprefixed env var names that current luxd (v1.26+) sets: VM_RUNTIME_ENGINE_ADDR
and VM_TRANSPORT. This matches the canonical names defined in
luxfi/vm/rpc/runtime/runtime.go. Earlier builds of this plugin
(via luxfi/vm ≤ v1.1.0) read LUX_VM_RUNTIME_ENGINE_ADDR/LUX_VM_TRANSPORT,
which are no longer recognized.