[CONSTITUTIONAL] AIP: ArbOS Version 40 Callisto

[Arbitrum]

[CONSTITUTIONAL] AIP: ArbOS Version 40 Callisto

Glad to see the proposal to support Pectra! When is the snapshot estimated for? Also, could there be any issues in the future with not adopting 7623 and having different calldata costs?

• The Snapshot vote has already been posted and has passed successfully at the time of writing. Not adopting EIP-7623 initially will change how Arbitrum chains calculate gas costs for calldata-heavy transactions, compared to L1, but will otherwise not alter how gas is estimated and charged to the user at the application layer. Operations and use cases that rely on calldata-heavy transactions will have their gas costs calculated the same way as it is done today, pre-Pectra.

[CONSTITUTIONAL] AIP: ArbOS Version 40 Callisto

Good and detailed description of the changes, and useful rationale for the EIPs that will not be applied. I have a question about the update date. Can something not work correctly in Arbitrum if the Ethereum network is already updated, but Arbitrum is not?

• Yes it is possible. Nitro node version 3.5.3 and nitro-contracts 3.0.0 or 2.1.3 should be used for chains settling to a Pectra-enabled Ethereum chain (like Sepolia or Holesky). Should this vote pass, a new Nitro version with ArbOS 40 will be released for Arbitrum one and Arbitrum nova node operators to use as a mandatory upgrade.

[CONSTITUTIONAL] AIP: ArbOS Version 40 Callisto

Overall, the Callisto upgrade appears to be a substantial step forward for Arbitrum in keeping up with Ethereum’s roadmap and we are in favour of it. Our only question @Arbitrum is whether developer tooling gaps and overall readiness have been accounted for to ensure a smooth transition amongst Arbitrum builders.

• Yes - Arbitrum builders across protocols and developer tooling have been consulted in anticipation for this upgrade on Pectra. This includes Orbit chain owners and Rollup-as-a-Service (RaaS) teams who may need to apply a small patch to ensure their chains are compatible with a parent chain that has upgraded to use Pectra.

[CONSTITUTIONAL] AIP: ArbOS Version 40 Callisto

Hello! Thanks for this exciting news! I have a few questions: About the process itself, can you clarify the difference between steps 2 and 6? I’m assuming this is the same vote (step 2), correct? And the steps 3-6 will follow that. About the timeline Do you have an update regarding the releases that were supposed to happen on Feb 13th? This sentence: “there is a strong likelihood that ArbOS 40 Callisto will be activated on Arbitrum One and Arbitrum Nova after Ethereum Mainnet upgrades to …

• Yes - Step 6 is the formal deployment of a release candidate of the Nitro node software that supports Pectra, while Step 2 is the temperature check vote held on Snapshot.
• It is our understanding that client teams have already released their Pectra-supported versions for Ethereum Holesky, including Geth’s 1.15.0 release. We strongly recommend following Ethereum Core Development discussions on https://ethereum-magicians.org/ and in their respective All Core Devs call, rather than this forum post.
• This is meant to be an informative message.

[CONSTITUTIONAL] AIP: ArbOS Version 40 Callisto

We vote FOR the proposal on Snapshot. We have reviewed EIPs to be included (and not included) in the Callisto upgrade and we find the rationale behind each decision clear and articulated. We are particularly excited about the EIP-7702 change to be included on Arbitrum One and Nova for users on those chains as we believe the change will drastically improve the user experience over time. We have a couple of questions: Even reading the detailed document, it wasn’t clear what the “technical deta…

• These changes refer to modifications that Orbit chains may want to make to ArbOS and to prevent versioning collisions between their modifications and official ArbOS releases. For example, if an Orbit chain wanted to modify ArbOS 40 and release their modifications as ArbOS 41, then the official Offchain Labs ArbOS release versions would not conflict since the next official version would be ArbOS 50.
• With any upgrade to the Arbitrum tech stack (including ArbOS 20 for Ethereum’s Dencun upgrade in March 2024), Orbit chains have full discretion over what ArbOS version to use for their chain and what customizations they want to make. We generally recommend Orbit chains upgrade to a new ArbOS release approximately 30 days after the release has been in production on Arbitrum One or Arbitrum Nova (pending governance).

[CONSTITUTIONAL] AIP: ArbOS Version 40 Callisto

voting Abstain on the current offchain vote because I have no idea of the risks this upgrade will entail without seeing the results of an independent audit to the smart contract code. And I also think the governance process for this proposal has not been followed in the best way it could. I think the Arbitrum DAO delegates should be asked to vote, even on a temperature check, in as much of a fully fleshed out proposal, as possible. This proposal is not ready to be voted on by delegates, in my op…

• As defined in the ArbitrumDAO’s Constitution, a temperature check vote is optional and is considered a matter of good governance practice. Furthermore, in the Steps to Implement section, there are clear steps that follow after the temperature check that a security audit by Trail of Bits is underway, and that a public report will be ready by the time this proposal is submitted to Tally for a formal on-chain vote. The vote here is to signal the readiness of the DAO to have this upgrade ready on both private devnets and Arbitrum Sepolia for further testing.