> ## Documentation Index
> Fetch the complete documentation index at: https://docs.optimism.io/llms.txt
> Use this file to discover all available pages before exploring further.

# System Config

The system configuration is a set of configurable chain parameters
defined in a contract on L1. These parameters can be changed through
the system config contract, emitting events that are picked up by
the \[rollup node derivation process]\[derivation]. To dive deeper
into the System Config, visit the
[OP Stack Specifications][specs].

## `SystemConfig` Type

The [`SystemConfig`][system-config] type is defined in
[`kona-genesis`][genesis].

Parameters defined in the [`SystemConfig`][system-config] are expected to be
updated through L1 receipts, using the [`update_with_receipts`][update] method.

## Holocene Updates

The [Holocene Hardfork][holocene] introduced an update to the
[`SystemConfig`][system-config] type, adding EIP-1559 parameters to the config.

The [`SystemConfig`][system-config] type in [`kona-genesis`][genesis] provides
a method called [`eip_1559_params`][eip] that returns the EIP-1559 parameters
encoded as a [`B64`][b64].

[specs]: https://specs.optimism.io/

[genesis]: https://docs.rs/kona-genesis/latest/kona_genesis/index.html

[system-config]: https://docs.rs/kona-genesis/latest/kona_genesis/struct.SystemConfig.html

[update]: https://docs.rs/kona-genesis/latest/kona_genesis/struct.SystemConfig.html#method.update_with_receipts

[holocene]: https://specs.optimism.io/protocol/holocene/overview.html

[eip]: https://docs.rs/kona-genesis/latest/kona_genesis/struct.SystemConfig.html#method.eip_1559_params

[b64]: https://docs.rs/kona-registry/latest/kona_registry/index.html