Tutorial 05 CKB Target Profiles

A target profile answers a simple question: which chain runtime are you preparing this source for?

CellScript now supports CKB as its only target profile. The CKB profile controls syscalls, source constants, header/runtime rules, artifact packaging, metadata policy, and verification boundaries.

What You Will Learn

• how to use the ckb profile consistently;
• why unsupported CKB runtime assumptions fail closed;
• how to check both assembly and ELF-compatible output paths;
• which CKB-specific details need review before deployment.

CKB Profile

Use this for CKB artifacts. This is the right choice when the output must follow CKB syscall, ELF, witness, Molecule, capacity, and builder expectations:

cellc build --target riscv64-elf --target-profile ckb

The CKB profile enforces:

• CKB syscall numbers;
• CKB source constants;
• CKB header ABI restrictions;
• raw ELF packaging without ABI trailer;
• Molecule-facing schema and entry witness metadata;
• CKB Blake2b release/deployment hash helper support;
• manifest-level hash_type, CellDep, and DepGroup reporting;
• capacity, tx-size, and builder-evidence requirements in constraints;
• CKB policy checks for unsupported runtime/stateful shapes.

Verify the result:

cellc verify-artifact build/main.elf --expect-target-profile ckb

Typical Checks

cellc check --target-profile ckb --json
cellc check --all-targets --target-profile ckb --json
cellc build --target riscv64-elf --target-profile ckb --json

If the source cannot build for CKB, inspect the policy violation. A failure is correct when the source depends on unsupported CKB behavior.

Practical CKB Rules

CKB work is usually easiest when the schema and transaction entry points are explicit from the beginning:

• prefer fixed-size persistent schema fields;
• keep action entry parameters explicit;
• use env::current_timepoint() for time-aware checks;
• record CKB hash_type, CellDeps, and DepGroups in Cell.toml;
• inspect cellc constraints --target-profile ckb --json before deployment;
• inspect witness layout with cellc abi or cellc entry-witness;
• avoid scheduler witness ABI;
• avoid unsupported signature/hash helper syscalls;
• use metadata and verify-artifact to confirm target profile and packaging.

For release-facing CKB evidence, also run the CellScript repository's CKB acceptance/final-hardening gate. Compiler metadata is necessary, but it is not a substitute for builder-backed transaction evidence, dry-run cycles, serialized tx-size evidence, and occupied-capacity checks.

Next

After choosing a profile, continue with Metadata, Verification, and Production Gates.