Updating rollups

Updating a rollup

It is often necessary to enable upgradeability of rollups.

More specifically, a user with appropriate rights can change the consensus implementation and the type of a certain rollup. Such a user can therefore modify the sequencing or verification procedures of a rollup.

In order to change the consensus, the function $\texttt{UpdateRollup()}$ needs to change the transparent proxy implementation.

In the upgrading procedure, the $\texttt{rollupCompatibilityID}$ comes into play:

• In order to avoid errors, we can only upgrade to a rollup type having the same compatibility identifier as the original one.

If this is not the case, the transaction is reverted, raising the $\texttt{UpdateNotCompatible}$ error.

Adding existing rollups

Rollups that are already deployed and working, do not follow any rollup type.

Such an existing rollup can be added to the $\texttt{RollupManager}$ via the $\texttt{addExistingRollup}()$ function, by specifying its current address.

When the verifier implements the $\texttt{IVerifierRollup}$ interface, it requests only for the raw consensus contract address, as it will not be used directly but through a proxy to allow upgradeability options.

As mentioned before, rollups that are deployed and already in operation can be added to the $\texttt{RollupManager}$ in order to allow unified management.

In this case, the $\texttt{addExistingRollup()}$ function is called.

Since the rollup has previously been initialized, the following information needs to be provided:

• The consensus contract, implementing the $\texttt{IPolygonRollupBase}$ interface.
• The verifier contract, implementing the $\texttt{IVerifierRollup}$ interface.
• The $\texttt{forkID}$ of the existent rollup.
• The $\texttt{chainID}$ of the existent rollup.
• The genesis block of the rollup.
• The $\texttt{rollupCompatibilityID}$.

Observe that most of these parameters were actually provided by the $\texttt{RollupType}$, but $\texttt{RollupData}$ of already existing rollups is constructed by hand, since they do not follow any rollup type as yet.