---
eip: 7840
title: Add blob schedule to EL config files
description: Include per-fork blob parameters in client configuration files
author: lightclient (@lightclient)
discussions-to: https://ethereum-magicians.org/t/add-blob-schedule-to-execution-client-configuration-files/22182
status: Final
type: Informational
created: 2024-12-12
---


## Abstract

Add a new object to client configuration files `blobSchedule` which lists the
target blob count per block and max blob count per block for each fork.

## Motivation

- ensure there is a way to dynamically adjust the target and max blob counts per
  block
- ensure there is a way to dynamically adjust the blob base fee update fraction
- avoid complex handshake over engine API

## Specification

Extend client configuration files with the object `blobSchedule`, which has the
following shape:

```json
"blobSchedule": {
  "cancun": {
    "target": 3,
    "max": 6,
    "baseFeeUpdateFraction": 3338477
  },
  "prague": {
    "target": 6,
    "max": 9,
    "baseFeeUpdateFraction": 5007716
  }
}
```

Clients must configure the target, max and baseFeeUpdateFraction per-fork. The behavior
when the configuration is missing or incomplete for a fork is undefined. Clients
are free to choose how to handle this situation.

## Rationale

Although maintaining the target and max blob only in the consensus client is
desirable, we acknowledge the reality that execution clients need these values
for various activities. For example, the `eth_feeHistory` RPC method returns a
field `blobGasUsedRatio` that does require the max, even though the core
protocol doesn't specifically need such value. Passing this value over the
engine API every block seem overkill so we believe a configuration value is a
good middle ground. Additionally, the `baseFeeUpdateFraction` parameter was added to adjust the responsiveness of blob gas pricing per fork.

## Backwards Compatibility

No backward compatibility issues found.

## Security Considerations

No security considerations found.

## Copyright

Copyright and related rights waived via [CC0](../LICENSE.md).