Virtual machines on the æternity blockchain

A smart contract is associated with a virtual machine for the execution of that contract. The æternity blockchain supports the virtual machine AEVM - A version of the Ethereum VM. The AEVM can also use different ABIs, and it is versioned to ensure that runs on earlier version can still be run to validate the chain in the presence of consensus breaking VM changes.

A Create Contract transaction and the contract state tree contains a 'vm_version' field and an 'abi_version' field. These fields describes the type and version of the virtual machine to use for the contract and the type and version of the application binary interface (ABI) of the contract. (Note that the serialization packs the version into one integer.)

The current meaning of the VM field is:

Value (hex)	Machine	Description
00	none	NO_VM ("Used" in oracles)
01	AEVM_01	For Sophia contracts on the AEVM
02	AEVM_01	For Solidity contracts on the AEVM
03	AEVM_02	Improved AEVM for Sophia, Minerva release
04	AEVM_03	Improved AEVM for Sophia, Fortuna release
05	FATE_01	For Sophia contracts using FATE (Lima release)
06	AEVM_04	Improved AEVM for Sophia, Lima release
07	FATE_02	For Sophia contracts using FATE (Iris release)
08	FATE_03	For Sophia contracts using FATE (Ceres release)
09-FFFF		UNUSED

The current meaning of the ABI field is:

Value (hex)	ABI	Description
00	raw string	No interpretation - used in oracles
01	Sophia_AEVM_01	For Sophia contracts on the AEVM
02	Solidity_01	For Solidity contracts on the AEVM
03	Sophia_FATE_01	For Sophia contracts using FATE
04-FFFF		UNUSED

Which VM versions are accepted are different based on consensus protocol versions.

Protocol version	Operation	Accepted VM values	Accepted ABI values
Roma	contract call/create	0x1	0x1
	oracle register	(Not applicable.)	0x0, 0x1
Minerva	contract call	0x1, 0x3	0x1
	contract create	0x3	0x1
	oracle register	(Not applicable.)	0x0, 0x1
Fortuna	contract call	0x1, 0x3, 0x4	0x1
	contract create	0x3, 0x4	0x1
	oracle register	(Not applicable.)	0x0, 0x1
Lima	contract call	0x1, 0x3, 0x4, 0x5, 0x6	0x1, 0x3
	contract create	0x5, 0x6	0x1, 0x3
	oracle register	(Not applicable.)	0x0, 0x1, 0x3
Iris	contract call	0x1, 0x3, 0x4, 0x5, 0x6, 0x7	0x1, 0x3
	contract create	0x7	0x3
	oracle register	(Not applicable.)	0x0, 0x3
Ceres	contract call	0x1, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8	0x1, 0x3
	contract create	0x8	0x3
	oracle register	(Not applicable.)	0x0, 0x3

The number after the machine name designates the version of the machine. In the future new versions of the machine can be implemented with new instructions, contracts using these machines must use a new vm_version number corresponding to the new machine version.

The ABI name correspond to the supported languages. All Ethereum VM languages uses the same ABI (Solidity_1). The languages can in the future be extended with new functionality and new ABIs reflected by the ABI version number.

For a description of each ABI see the corresponding language description: Sophia, Solidity.

The æternity Ethereum virtual machine AEVM

See The AEVM.

Consensus breaking changes between AEVM versions

AEVM_01 -> AEVM_02

• Oracle query fee of unknown oracle
  • AEVM_01: Succeeded with bogus value
  • AEVM_02: Fails with exception
• New crypto/hash primitives
• New VM instructions (bit shift operations)

AEVM_02 -> AEVM_03

• New primitive operations (Auth.tx_hash)
• New crypto primitives

AEVM_03 -> AEVM_04

• New crypto primitives
• Memory gas adjustments
• Updated arguments for AENS-functions
• Support for payable

Consensus breaking changes between FATE versions

FATE_01 -> FATE_02

• Added operations
  • Crypto pairing operations (BLS12-381)
  • String functions (to_list, from_list, etc)
  • AENS.update, AENS.lookup, Oracle.expire
  • Chain.create, Chain.clone, Chain.bytecode_hash, Call.fee
• Bug fixes
• Gas model adjustments

FATE_02 -> FATE_03

• Added operations:
  • bitwise operations on integers (band, bor, bxor, bnot, << and >>)
  • Address.to_bytes - converting an address to its binary representation
  • Int.mulmod - a combined multiplication and modulus operation for efficiency
  • Crypto.poseidon - a ZK/SNARK friendly hash function
  • Arbitrary sized binary arrays: Bytes.split_any, Bytes.to_fixed_size, Bytes.size, String.to_bytes, and Int.to_bytes