Meepo Hard Fork is Now Live

English CKB Development & Technical Discussion
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As of July 1st, 2025 (UTC+8), epoch 12293, the Meepo hard fork is now live on the Nervos CKB Mainnet — implementing the CKB Consensus Changes.

Key Features

1. CKB-VM V2

This hard fork activates VM Version 2, a major upgrade to the CKB-VM. It introduces:

  • Versioned VM support: CKB-VM v2 introduces a versioning mechanism that allows each Script to explicitly specify which VM version it runs on. With the hash_type supporting four values (type, data, data1 , data2), developers can control whether a Script automatically adopts future VM upgrades.
  • Access to new syscalls like spawn、pipe 、read、write, etc. — only available in VM v2
  • Performance optimizations, including memory operations (mops), better cycle counting, and improved testing coverage

For full details, see RFC0049 – VM version2.

2. Spawn Syscall

The spawn syscall is the major update in this hard fork. Spawn lets one Script invoke another with arguments and shared state.

Instead of writing large monolithic Scripts, developers can now build modular and reusable components.

In addition to spawn, several related syscalls— such as pipe 、read、write — were also introduced in this hard fork to support structured Script composition. You can find the full list and implementation details in RFC0050 – VM Syscalls 3.

Tools & Upgrade Requirements

To fully support the new features introduced by this hard fork, please ensure you’re using the latest versions of the tools. Below are the minimum recommended versions.

CKB Node

Core Components

Standard Libraries

SDKs

Development Tools

Virtual Machines

Related RFCs

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