VM Module Reference

The VM module (x/vm) is the core EVM implementation that enables Ethereum compatibility on Cosmos chains. It provides the EVM runtime, state management, precompiled contracts, and transaction processing.

Module Overview

Purpose: Execute Ethereum smart contracts and process EVM transactions within the Cosmos SDK framework Key Functionality:

EVM state transitions and transaction execution
Ethereum fork activation management (Homestead, Berlin, London, Shanghai, Cancun, Prague, etc.)
Native precompiled contracts for Cosmos module access
EVM-to-Cosmos and Cosmos-to-EVM account bridging
Gas metering and fee handling
Historical state queries with configurable retention

Source Code: x/vm Parameter Defaults: x/vm/types/params.go

Configuration Methods

The VM module can be configured through genesis.json before chain launch. Here are the three primary methods:

Method 1: Direct JSON Editing

Edit ~/.evmd/config/genesis.json directly:

{
  "app_state": {
    "vm": {
      "params": {
        "evm_denom": "atest",
        "extra_eips": [3855],
        "active_static_precompiles": ["0x0000000000000000000000000000000000000800"],
        "access_control": {
          "create": {"access_type": 0},
          "call": {"access_type": 0}
        }
      }
    }
  }
}

Method 2: Using jq Command-Line Tool

Programmatically modify genesis using jq (as seen in local_node.sh):

# Set evm_denom
jq '.app_state["vm"]["params"]["evm_denom"]="atest"' genesis.json > tmp.json && mv tmp.json genesis.json

# Enable all precompiles (matches x/vm/types/precompiles.go:22-32)
jq '.app_state["vm"]["params"]["active_static_precompiles"]=[
  "0x0000000000000000000000000000000000000100",  # P256
  "0x0000000000000000000000000000000000000400",  # Bech32
  "0x0000000000000000000000000000000000000800",  # Staking
  "0x0000000000000000000000000000000000000801",  # Distribution
  "0x0000000000000000000000000000000000000802",  # ICS20
  "0x0000000000000000000000000000000000000803",  # Vesting
  "0x0000000000000000000000000000000000000804",  # Bank
  "0x0000000000000000000000000000000000000805",  # Governance
  "0x0000000000000000000000000000000000000806"   # Slashing
]' genesis.json > tmp.json && mv tmp.json genesis.json

# Enable extra EIP
jq '.app_state["vm"]["params"]["extra_eips"]=[3855]' genesis.json > tmp.json && mv tmp.json genesis.json

Method 3: Using genesis CLI Commands

Some parameters can be set through CLI commands (though most VM params require genesis.json editing):

# Genesis file is created with:
evmd init <moniker> --chain-id <chain-id>

# Then manually edit genesis.json for VM params
# No direct CLI command for VM param modification

Parameters

evm_denom

What It Does: Specifies which bank module denomination to use as the native EVM token (gas token). Type: string Valid Values: Must match a base denomination from bank metadata configuration Default: "uatom" (params.go:21) Configuration:

# Using jq
jq '.app_state["vm"]["params"]["evm_denom"]="atest"' genesis.json > tmp.json && mv tmp.json genesis.json

{
  "vm": {
    "params": {
      "evm_denom": "atest"
    }
  }
}

Critical Requirements:

MUST match bank.denom_metadata[0].base
MUST match staking.params.bond_denom
MUST match mint.params.mint_denom

Impact: This is the token users pay for EVM gas, displayed in MetaMask balances, and used for all EVM operations. Examples:

"atest" - For 18 decimal token (atto prefix: 10^18)
"ustake" - For 6 decimal token (micro prefix: 10^6)

Common Errors:

Mismatch with bank metadata causes EVM transactions to fail
Wrong decimal places leads to incorrect balance displays

extra_eips

What It Does: Enables additional Ethereum Improvement Proposals beyond the default fork activations. Type: []int64 (array of EIP numbers) Valid Values: Any activatable EIP number Default: [] (empty - all EIPs come from chain_config fork configuration) (params.go:22) Configuration:

# Using jq
jq '.app_state["vm"]["params"]["extra_eips"]=[3855, 2929]' genesis.json > tmp.json && mv tmp.json genesis.json

{
  "vm": {
    "params": {
      "extra_eips": [3855, 2929]
    }
  }
}

Common EIPs:

EIP	Description	Typical Use Case
3855	PUSH0 instruction	Gas optimization for contracts
2200	Net gas metering for SSTORE	Reduces gas costs
2929	Gas cost increases for state access	Security hardening
3198	BASEFEE opcode	EIP-1559 base fee queries
3529	Reduction in refunds	Gas accounting changes

Validation: Checked against list of activatable EIPs (params.go:182-200) Impact:

Enables opcodes/features not in your default fork configuration
Useful for testing upcoming Ethereum features
Can break compatibility if not carefully managed

Recommendation: Leave empty unless you need specific EIPs for custom contracts or testing

active_static_precompiles

What It Does: List of precompiled contract addresses to enable for Cosmos module access from EVM. Type: []string (array of hex addresses) Valid Values: Addresses from the available precompiles list (precompiles.go:4-15) Default: [] (empty - no precompiles enabled) (params.go:23) Configuration:

# Using jq - Enable all precompiles (from local_node.sh:243)
jq '.app_state["vm"]["params"]["active_static_precompiles"]=[
  "0x0000000000000000000000000000000000000100",
  "0x0000000000000000000000000000000000000400",
  "0x0000000000000000000000000000000000000800",
  "0x0000000000000000000000000000000000000801",
  "0x0000000000000000000000000000000000000802",
  "0x0000000000000000000000000000000000000803",
  "0x0000000000000000000000000000000000000804",
  "0x0000000000000000000000000000000000000805",
  "0x0000000000000000000000000000000000000806"
]' genesis.json > tmp.json && mv tmp.json genesis.json

{
  "vm": {
    "params": {
      "active_static_precompiles": [
        "0x0000000000000000000000000000000000000100",
        "0x0000000000000000000000000000000000000400",
        "0x0000000000000000000000000000000000000800"
      ]
    }
  }
}

Available Precompiles:

Address	Name	Module	Description
`0x0100`	P256	Cryptography	P256 elliptic curve operations
`0x0400`	Bech32	Addressing	Convert between Bech32 and hex addresses
`0x0800`	Staking	x/staking	Delegate, undelegate, redelegate operations
`0x0801`	Distribution	x/distribution	Claim staking rewards, set withdrawal address
`0x0802`	ICS20	IBC Transfer	IBC token transfers via EVM
`0x0803`	Vesting	x/vesting	Vesting account operations
`0x0804`	Bank	x/bank	Native Cosmos token transfers
`0x0805`	Gov	x/gov	Submit and vote on governance proposals
`0x0806`	Slashing	x/slashing	Query validator slashing info

Production Recommendations:

Enable only needed precompiles for security and gas efficiency
Commonly enabled: 0x0100 (P256), 0x0400 (Bech32), 0x0800 (Staking), 0x0804 (Bank)
IBC chains: Also enable 0x0802 (ICS20)
Governance participation: Enable 0x0805 (Gov)

Security Note: Each enabled precompile increases attack surface. Only enable precompiles your applications will actually use. Default evmd Example: Enables ALL precompiles for development convenience (local_node.sh:243)

evm_channels

What It Does: Whitelisted IBC channel IDs that the ICS20 precompile can use for token transfers. Type: []string (array of channel IDs) Valid Values: Channel IDs matching format channel-{N} where N is a non-negative integer Default: [] (empty - no channels whitelisted) (params.go:24) Configuration:

{
  "vm": {
    "params": {
      "evm_channels": ["channel-0", "channel-5", "channel-42"]
    }
  }
}

Validation: Each channel must match regex pattern (params.go:80-96) Impact:

Restricts which IBC channels the ICS20 precompile (0x0802) can transfer tokens through
Empty list means ICS20 precompile cannot perform any IBC transfers
Provides security control over cross-chain token movements

When to Configure:

Only needed if you enable ICS20 precompile (0x0802)
Set after establishing IBC connections with other chains
Update via governance when adding new IBC routes

Example Use Case: Enable IBC transfers only to trusted chains via specific channels

access_control

What It Does: Defines permission model for contract deployment (CREATE/CREATE2) and contract calls. Type: Object with create and call fields, each containing access_type and optional access_control_list Valid Values:

access_type: 0 (Permissionless), 1 (Restricted), 2 (Permissioned)
access_control_list: Array of addresses (only used with Restricted or Permissioned)

Default: Permissionless for both (params.go:30-48) Configuration:

{
  "vm": {
    "params": {
      "access_control": {
        "create": {
          "access_type": 2,
          "access_control_list": [
            "0x1234567890123456789012345678901234567890",
            "0xabcdefabcdefabcdefabcdefabcdefabcdefabcd"
          ]
        },
        "call": {
          "access_type": 0
        }
      }
    }
  }
}

Access Types: Type 0 - Permissionless (Default):

Anyone can perform the operation
Standard Ethereum behavior
Recommended for public chains

Type 1 - Restricted:

Everyone EXCEPT addresses in access_control_list can perform operation
Blacklist model
Useful for blocking specific malicious actors

Type 2 - Permissioned:

ONLY addresses in access_control_list can perform operation
Whitelist model
Useful for private/consortium chains or phased launches

Common Configurations: Public Chain (Default):

{
  "create": {"access_type": 0},
  "call": {"access_type": 0}
}

Permissioned Deployment, Public Usage:

{
  "create": {
    "access_type": 2,
    "access_control_list": ["0x..."]
  },
  "call": {"access_type": 0}
}

Validation: Enforced in (params.go:140-180) Impact:

Controls who can deploy contracts (important for chain security)
Controls who can call existing contracts (rarely restricted)
Can be updated via governance proposals after launch

Recommendation: Use Type 0 (Permissionless) for public EVM chains to maintain Ethereum compatibility

history_serve_window

What It Does: Number of recent blocks to keep for historical EVM queries (eth_getBlockByNumber, eth_getLogs, etc.). Type: uint64 Valid Values: Any non-negative integer Default: 8192 blocks (params.go:50) Configuration:

{
  "vm": {
    "params": {
      "history_serve_window": 8192
    }
  }
}

Impact: Storage:

Larger window = more disk space required
Smaller window = less disk space usage
Each block stores EVM state diffs and receipts

Query Capability:

Queries beyond history_serve_window will fail
Block explorers need sufficient history for user queries
DeFi analytics may require longer history

Performance:

Very large windows can slow down state pruning
Affects database size and sync time

Common Values:

8192 - Default (roughly 11 hours at 5s blocks)
100000 - Extended history (roughly 5.8 days at 5s blocks)
1000000 - Full history (roughly 58 days at 5s blocks)
0 - No history retention (not recommended for RPC nodes)

Recommendations:

Archive Nodes: Set to very large number or 0 (unlimited)
RPC Nodes: 100,000 - 1,000,000 blocks
Validator Nodes: Can use default 8192 (validators don’t serve RPC)

Related: Works with EIP-2935 for historical block hash access

extended_denom_options

What It Does: Enables 18-decimal EVM representation for non-18-decimal Cosmos tokens. Required for 6-decimal tokens like ustake. Type: []ExtendedDenomOption - Array of objects mapping Cosmos denoms to EVM extended denoms Valid Values: Each entry must have a valid denom pair following the extended denom pattern Default: [] (empty - no extended denoms) (params.go:25) Configuration:

{
  "vm": {
    "params": {
      "extended_denom_options": [
        {
          "native_denom": "ustake",
          "extended_denom": "astake"
        }
      ]
    }
  }
}

When Required:

18 decimals: NOT required - standard bank module works
6 decimals: REQUIRED - must add extended_denom_options
Other decimals: REQUIRED - must add extended_denom_options

Extended Denom Patterns:

u prefix (micro, 10^6) → a prefix (atto, 10^18): ustake → astake
n prefix (nano, 10^9) → a prefix (atto, 10^18): ntoken → atoken
Any other → add evm prefix: stake → evmstake

How It Works:

Native 6-decimal token: ustake (smallest unit)
Extended 18-decimal representation: astake (for EVM)
1 ustake = 10^12 astake
PreciseBank module handles fractional conversions

Example: 6 Decimal Token:

{
  "app_state": {
    "vm": {
      "params": {
        "evm_denom": "ustake",
        "extended_denom_options": [
          {
            "native_denom": "ustake",
            "extended_denom": "astake"
          }
        ]
      }
    }
  }
}

Related Configuration: Requires PreciseBank Module to be included in app.go See Also: Token Configuration Guide for complete decimal configuration details

Complete Configuration Example

Based on local_node.sh:

#!/bin/bash

GENESIS="$HOME/.evmd/config/genesis.json"
TMP_GENESIS="$HOME/.evmd/config/tmp_genesis.json"

# Set EVM denomination
jq '.app_state["vm"]["params"]["evm_denom"]="atest"' "$GENESIS" >"$TMP_GENESIS" && mv "$TMP_GENESIS" "$GENESIS"

# Enable all precompiles for development
jq '.app_state["vm"]["params"]["active_static_precompiles"]=[
  "0x0000000000000000000000000000000000000100",
  "0x0000000000000000000000000000000000000400",
  "0x0000000000000000000000000000000000000800",
  "0x0000000000000000000000000000000000000801",
  "0x0000000000000000000000000000000000000802",
  "0x0000000000000000000000000000000000000803",
  "0x0000000000000000000000000000000000000804",
  "0x0000000000000000000000000000000000000805",
  "0x0000000000000000000000000000000000000806"
]' "$GENESIS" >"$TMP_GENESIS" && mv "$TMP_GENESIS" "$GENESIS"

# Validate genesis
evmd genesis validate-genesis --home "$HOME/.evmd"

Or in genesis.json directly:

{
  "app_state": {
    "vm": {
      "params": {
        "evm_denom": "atest",
        "extra_eips": [],
        "active_static_precompiles": [
          "0x0000000000000000000000000000000000000100",
          "0x0000000000000000000000000000000000000400",
          "0x0000000000000000000000000000000000000800",
          "0x0000000000000000000000000000000000000801",
          "0x0000000000000000000000000000000000000802",
          "0x0000000000000000000000000000000000000803",
          "0x0000000000000000000000000000000000000804",
          "0x0000000000000000000000000000000000000805",
          "0x0000000000000000000000000000000000000806"
        ],
        "evm_channels": [],
        "access_control": {
          "create": {
            "access_type": 0
          },
          "call": {
            "access_type": 0
          }
        },
        "history_serve_window": 8192,
        "extended_denom_options": []
      },
      "chain_config": {
        "chain_id": "9001",
        "homestead_block": "0",
        "dao_fork_block": "0",
        "dao_fork_support": true,
        "eip150_block": "0",
        "eip155_block": "0",
        "eip158_block": "0",
        "byzantium_block": "0",
        "constantinople_block": "0",
        "petersburg_block": "0",
        "istanbul_block": "0",
        "muir_glacier_block": "0",
        "berlin_block": "0",
        "london_block": "0",
        "arrow_glacier_block": "0",
        "gray_glacier_block": "0",
        "merge_netsplit_block": "0",
        "shanghai_time": "0",
        "cancun_time": "0",
        "prague_time": "0"
      }
    }
  }
}

Building Your Chain Guide - Main configuration walkthrough
Chain Customization Checklist - Complete parameter checklist
Token Configuration Guide - Token decimals and evm_denom setup
Fee Market Module - EIP-1559 fee configuration
local_node.sh - Reference implementation

Source Code References

Module Implementation: x/vm
Parameter Types: x/vm/types/params.go
Precompile Addresses: x/vm/types/precompiles.go
Chain Config: x/vm/types/chain_config.go
Genesis Setup: local_node.sh

Cosmos EVM

Vm

VM Module Reference

Module Overview

Configuration Methods

Method 1: Direct JSON Editing

Method 2: Using jq Command-Line Tool

Method 3: Using genesis CLI Commands

Parameters

evm_denom

extra_eips

active_static_precompiles

evm_channels

access_control

history_serve_window

extended_denom_options

Complete Configuration Example

Source Code References

Cosmos EVM

​VM Module Reference

​Module Overview

​Configuration Methods

​Method 1: Direct JSON Editing

​Method 2: Using jq Command-Line Tool

​Method 3: Using genesis CLI Commands

​Parameters

​evm_denom

​extra_eips

​active_static_precompiles

​evm_channels

​access_control

​history_serve_window

​extended_denom_options

​Complete Configuration Example

​Related Documentation

​Source Code References

VM Module Reference

Module Overview

Configuration Methods

Method 1: Direct JSON Editing

Method 2: Using jq Command-Line Tool

Method 3: Using genesis CLI Commands

Parameters

evm_denom

extra_eips

active_static_precompiles

evm_channels

access_control

history_serve_window

extended_denom_options

Complete Configuration Example

Related Documentation

Source Code References