holocene: operator fee

specs/SUMMARY.md

@@ -56,6 +56,8 @@
       - [Predeploys](./protocol/holocene/predeploys.md)
       - [L1 Block Attributes](./protocol/holocene/l1-attributes.md)
       - [Configurability](./protocol/holocene/configurability.md)
+      - [System Config](./protocol/holocene/system-config.md)
+
 - [Governance]()
   - [Governance Token](./governance/gov-token.md)
 - [Experimental]()

specs/experimental/op-contracts-manager.md

@@ -1,6 +1,5 @@
 # OP Contracts Manager
 
-[`op-contracts/v1.4.0`]: https://github.com/ethereum-optimism/optimism/releases/tag/op-contracts%2Fv1.6.0
 [Optimism Monorepo releases]: https://github.com/ethereum-optimism/optimism/releases
 [contract releases]: https://github.com/ethereum-optimism/optimism/blob/develop/packages/contracts-bedrock/VERSIONING.md
 [standard configuration]: ../protocol/configurability.md

specs/protocol/configurability.md

@@ -408,8 +408,8 @@ existing [permissioned dispute games](../fault-proof/stage-one/bridge-integratio
 [^of-gnosis-safe-l1]<br/>
 **Notes:** Optimism Foundation (OF) multisig
 leveraging [battle-tested software](https://github.com/safe-global/safe-smart-account). This role is only active when
-the `OptimismPortal` respected game type is [
-`PERMISSIONED_CANNON`](https://github.com/ethereum-optimism/optimism/blob/op-contracts/v1.5.0/packages/contracts-bedrock/src/dispute/lib/Types.sol#L31).<br/>
+the `OptimismPortal` respected game type is [`PERMISSIONED_CANNON`]
+(<https://github.com/ethereum-optimism/optimism/blob/op-contracts/v1.5.0/packages/contracts-bedrock/src/dispute/lib/Types.sol#L31>).<br/>
 
 ### [Guardian address](https://github.com/ethereum-optimism/optimism/blob/c927ed9e8af501fd330349607a2b09a876a9a1fb/packages/contracts-bedrock/src/L1/SuperchainConfig.sol#L50)
 
@@ -429,8 +429,8 @@ with [permissioned dispute games](../fault-proof/stage-one/bridge-integration.md
 L1.<br/>
 **Administrator:** [L1 Proxy Admin](#admin-roles)<br/>
 **Requirement:** No requirement<br/>
-**Notes:** This role is only active when the `OptimismPortal` respected game type is [
-`PERMISSIONED_CANNON`](https://github.com/ethereum-optimism/optimism/blob/op-contracts/v1.5.0/packages/contracts-bedrock/src/dispute/lib/Types.sol#L31).
+**Notes:** This role is only active when the `OptimismPortal` respected game type is [`PERMISSIONED_CANNON`]
+(<https://github.com/ethereum-optimism/optimism/blob/op-contracts/v1.5.0/packages/contracts-bedrock/src/dispute/lib/Types.sol#L31>).
 The `L1ProxyAdmin` sets the implementation of the `PERMISSIONED_CANNON` game type. Thus, it determines the proposer
 configuration of the permissioned dispute game.<br/>
 

specs/protocol/holocene/configurability.md

@@ -55,7 +55,7 @@ The following `ConfigUpdate` enum is defined where the `CONFIG_VERSION` is `uint
 | Name | Value | Definition | Usage |
 | ---- | ----- | --- | -- |
 | `BATCHER` | `uint8(0)` | `abi.encode(address)` | Modifies the account that is authorized to progress the safe chain |
-| `FEE_SCALARS` | `uint8(1)` | `(uint256(0x01) << 248) \| (uint256(_blobbasefeeScalar) << 32) \| _basefeeScalar` | Modifies the fee scalars |
+| `FEE_SCALARS` | `uint8(1)` | `(uint256(0x01) << 248) \| (uint256(_operatorFeeScalar) <<  108 \| (uint256(_operatorFeeConstant) << 96 \| (uint256(_blobBaseFeeScalar) << 32) \| _baseFeeScalar` | Modifies the fee scalars |
 | `GAS_LIMIT` | `uint8(2)` | `abi.encode(uint64 _gasLimit)` | Modifies the L2 gas limit |
 | `UNSAFE_BLOCK_SIGNER` | `uint8(3)` | `abi.encode(address)` | Modifies the account that is authorized to progress the unsafe chain |
 | `EIP_1559_PARAMS` | `uint8(4)` | `uint256(uint64(_denominator)) << 32 \| uint64(_elasticity)` | Modifies the EIP-1559 denominator and elasticity |

specs/protocol/holocene/derivation.md

@@ -341,5 +341,7 @@ The Holocene hardfork activation block contains the following transactions, in t
   - L1Block deployment
   - Update L1Block Proxy ERC-1967 Implementation
   - L1Block Enable Holocene
+  - GasPriceOracle deployment
+  - Update GasPriceOracle Proxy ERC-1967 Implementation
   - OptimismMintableERC20Factory deployment
   - Update OptimismMintableERC20Factory Proxy ERC-1967 Implementation

specs/protocol/holocene/exec-engine.md

@@ -11,6 +11,9 @@
     - [Rationale](#rationale)
     - [Forwards Compatibility Considerations](#forwards-compatibility-considerations)
     - [Client Implementation Considerations](#client-implementation-considerations)
+- [Fees](#fees)
+  - [Operator fees](#operator-fees)
+    - [Configuring scalars](#configuring-scalars)
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
@@ -75,3 +78,37 @@ directly store this information.
 
 [l2-to-l1-mp]: ../../protocol/predeploys.md#L2ToL1MessagePasser
 [output-root]: ../../glossary.md#l2-output-root
+
+## Fees
+
+New OP stack variants have different resource consumption patterns, and thus require a more flexible
+pricing model. To enable more customizable fee structures, Holocene adds a new component to the fee
+calculation: the `operatorFee`, which is parameterized by two scalars: the `operatorFeeScalar`
+and the `operatorFeeConstant`.
+
+### Operator fees
+
+The operator fee, in wei, is set as follows:
+
+`operatorFee = (gasUsed * operatorFeeScalar / 1e6) + operatorFeeConstant`
+
+Where:
+
+- `gasUsed` is amount of gas used by the transaction.
+- `operatorFeeScalar` is a `uint32` scalar set by the chain operator, scaled by `1e6`.
+- `operatorFeeConstant` is a `uint64` scalar set by the chain operator.
+
+These collected fees are sent to the `SequencerFeeVault`.
+
+#### Configuring scalars
+
+`operatorFeeScalar` and `operatorFeeConstant` are loaded in a similar way to the `baseFeeScalar` and
+`blobBaseFeeScalar` used in the [`L1Fee`](../../protocol/exec-engine.md#ecotone-l1-cost-fee-changes-eip-4844-da).
+calculation. In more detail, these scalars can be accessed in two interchangable ways.
+
+- read from the deposited L1 attributes (`operatorFeeScalar` and `operatorFeeConstant`) of the current L2 block
+- read from the L1 Block Info contract (`0x4200000000000000000000000000000000000015`)
+  - using the respective solidity getter functions (`operatorFeeScalar`, `operatorFeeConstant`)
+  - using direct storage-reads:
+    - Operator fee scalar as big-endian `uint32` in slot `3` at offset `20`.
+    - Operator fee constant as big-endian `uint64` in slot `3` at offset `16`.

specs/protocol/holocene/l1-attributes.md

@@ -26,3 +26,14 @@ The L1 block attributes transaction is updated to include the EIP-1559 parameter
 | batcherHash       | bytes32 | 132-163        | 5       |
 | eip1559Denominator   | uint64  | 164-171        | 6       |
 | eip1559Elasticity    | uint64  | 172-179        |         |
+| operatorFeeScalar    | uint32  | 180-183     |         |
+| operatorFeeConstant    | uint64  | 184-191   |         |
+
+In the first L2 block after the Holocene activation block, the Holocene L1 attributes are first used.
+
+The pre-Holocene values are migrated over 1:1.
+Blocks after the Holocene activation block contain all pre-Holocene values 1:1,
+and also set the following new attributes:
+
+- The `operatorFeeScalar` is set to `0`.
+- The `operatorFeeConstant` is set to `0`.

specs/protocol/holocene/overview.md

@@ -26,3 +26,4 @@ This document is not finalized and should be considered experimental.
 - [Predeploys](./predeploys.md)
 - [L1 Block Attributes](./l1-attributes.md)
 - [Configurability](./configurability.md)
+- [System Config](./system-config.md)

specs/protocol/holocene/predeploys.md

@@ -30,6 +30,9 @@
     - [Interface](#interface-3)
   - [L2StandardBridge](#l2standardbridge)
     - [Interface](#interface-4)
+  - [GasPriceOracle](#gaspriceoracle)
+    - [Interface](#interface-5)
+      - [`getOperatorFee`](#getoperatorfee)
   - [OptimismMintableERC721Factory](#optimismmintableerc721factory)
 - [Security Considerations](#security-considerations)
   - [GovernanceToken](#governancetoken)
@@ -255,6 +258,21 @@ The following functions are updated to read from the `L1Block` contract by calli
 - `otherBridge()(address)`
 - `OTHER_BRIDGE()(address)`
 
+### GasPriceOracle
+
+In order to maintain accurate offchain fee estimation, the `GasPriceOracle` must be updated to allow users
+to estimate the operator fee.
+
+#### Interface
+
+##### `getOperatorFee`
+
+This function calculates the operator fee based on the expected amount of gas used for a certain transaction.
+
+```function
+function getOperatorFee(uint256 gasUsed)(uint256)
+```
+
 ### OptimismMintableERC721Factory
 
 The chain id is no longer read from storage but instead is read from the `L1Block` contract by calling

specs/protocol/holocene/system-config.md

@@ -0,0 +1,39 @@
+# System Config
+
+<!-- START doctoc generated TOC please keep comment here to allow auto update -->
+<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
+**Table of Contents**
+
+- [System config contents (version 0)](#system-config-contents-version-0)
+  - [Scalars](#scalars)
+    - [Holocene `scalar`, `overhead` (`uint256,uint256`) change](#holocene-scalar-overhead-uint256uint256-change)
+
+<!-- END doctoc generated TOC please keep comment here to allow auto update -->
+
+## System config contents (version 0)
+
+### Scalars
+
+In order to allow rollup operators to adjust the new `operatorFeeScalar` and `operatorFeeConstant`, a change to
+the `scalar` and `overhead` encoding is necessary.
+
+#### Holocene `scalar`, `overhead` (`uint256,uint256`) change
+
+After Holocene activation:
+
+- A new version to the `scalar` encoding is added. It is described as follows.
+
+\*Byte ranges are indicated with `[` (inclusive) and `)` (exclusive).
+
+- `0`: scalar-version byte
+- `[1, 32)`: depending scalar-version:
+  - Scalar-version `2`:
+    - `[1, 8)`: padding, must be zero.
+    - `[12, 16)`: big-endian `uint32`, encoding the `operatorFeeScalar`
+    - `[16, 24)`: big-endian `uint64`, encoding the `operatorFeeConstant`
+    - `[24, 28)`: big-endian `uint32`, encoding the `blobBaseFeeScalar`
+    - `[28, 32)`: big-endian `uint32`, encoding the `baseFeeScalar`
+    - This version adds the `operatorFeeScalar` and the `operatorFeeConstant`.
+
+The `operatorFeeScalar` and `operatorFeeConstant` are incorporated into the L2 through the
+[Holocene L1 attributes deposit transaction calldata](l1-attributes.md).