Koute
b0f34e4b29
This PR adds a new PolkaVM-based executor to Substrate. - The executor can now be used to actually run a PolkaVM-based runtime, and successfully produces blocks. - The executor is always compiled-in, but is disabled by default. - The `SUBSTRATE_ENABLE_POLKAVM` environment variable must be set to `1` to enable the executor, in which case the node will accept both WASM and PolkaVM program blobs (otherwise it'll default to WASM-only). This is deliberately undocumented and not explicitly exposed anywhere (e.g. in the command line arguments, or in the API) to disincentivize anyone from enabling it in production. If/when we'll move this into production usage I'll remove the environment variable and do it "properly". - I did not use our legacy runtime allocator for the PolkaVM executor, so currently every allocation inside of the runtime will leak guest memory until that particular instance is destroyed. The idea here is that I will work on the https://github.com/polkadot-fellows/RFCs/pull/4 which will remove the need for the legacy allocator under WASM, and that will also allow us to use a proper non-leaking allocator under PolkaVM. - I also did some minor cleanups of the WASM executor and deleted some dead code. No prdocs included since this is not intended to be an end-user feature, but an unofficial experiment, and shouldn't affect any current production user. Once this is production-ready a full Polkadot Fellowship RFC will be necessary anyway.
PVF Host
This is the PVF host, responsible for responding to requests from Candidate Validation and spawning worker tasks to fulfill those requests.
See also:
- for more information: the Implementer's Guide
- for an explanation of terminology: the Glossary
Running basic tests
Running cargo test in the pvf/ directory will run unit and integration
tests.
Note: some tests run only under Linux, x86-64, and/or with the
ci-only-tests feature enabled.
See the general Testing instructions for more information on running tests and observing logs.
Running a test-network with zombienet
Since this crate is consensus-critical, for major changes it is highly recommended to run a test-network. See the "Behavior tests" section of the Testing docs for full instructions.
To run the PVF-specific zombienet test:
RUST_LOG=parachain::pvf=trace zombienet --provider=native spawn zombienet_tests/functional/0001-parachains-pvf.toml
Testing on Linux
Some of the PVF functionality, especially related to security, is Linux-only, and some is x86-64-only. If you touch anything security-related, make sure to test on Linux x86-64! If you're on a Mac, you can either run a VM or you can hire a VPS and use the open-source tool EternalTerminal to connect to it.1
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Unlike ssh, ET preserves your session across disconnects, and unlike another popular persistent shell, mosh, it allows scrollback. ↩︎