Do we need to regenerate genesis binary after modifying runtime?

[hackfisher]

Related #388

https://github.com/paritytech/substrate/blob/v2.0.0-alpha.4/frame/system/src/lib.rs#L409

https://github.com/paritytech/substrate/blob/v2.0.0-alpha.4/bin/node/cli/src/chain_spec.rs#L232

[hackfisher]

This only applies to cases of resetting or purging network, for long running networks, since the genesis binary will not be used, they will not be confused by this question.

[aurexav]

Xavier:

Hi.
Is necessary to re build-spec after modifying runtime?
Just for starting a new network, not runtime-upgrade.
I only rebuild it when the chain_spec.rs changed.

Jam:

if there are new config()s, yes, otherwise I don't believe so.

Xavier:

We modify the primitives/runtime/digest.rs and deposit_log a new custom DigestItem in our frame/module. Got Number of digest items must match that calculated.
These modification did't touch the chain_spec.rs or config().
But we've to rebuild it.
If we add a flag `--execution=Native`, this panic gone.

frame_system: Some(SystemConfig {
    code: WASM_BINARY.to_vec(),
    changes_trie_config: Default::default(),
}),

Rebuild it to upgrade the WASM_BINARY?

Jam:

correct - the chain spec contains the entire wasm blob - either the native or json formats - but usually just rebuilding the node or runtime is sufficient for that 

[aurexav]

Yes, for deploying a brand new network.