Response from whalesniper
Both/Either. You can spread code across multiple rollups to make one
big kernel, so I'm sure you can implement upgrading logic. As long as
it's known beforehand (or handled by a DAO), I see little issue with
it.
Response from daniel hines
Rollup kernels can modify their own code. See the installer kernel for
an example.
How this plays out is under the control of the SORU kernel developer.
Personally I would want upgrades to a rollup I used to be protected by
multisig and time delay!
Answer from Nomadic labs
It depends on how the rollup is configured when deployed. Both rollups
with admin keys and 100% trustless rollups are possible on Tezos.
There is a special location in the durable storage of the WASM PVM
where the kernel – the DApp code – is located. It is up to the DApp
logic to implement an update mechanism by modifying this location and
by rebooting the WASM machine. See the “installer kernel” that works
following this principle:
https://gitlab.com/tezos/kernel/-/blob/main/installer_kernel/src/reveal_installer.rs