Bflat Test Suite

Test suite for Nethermind's Bflat, a fork of the C# NativeAOT compiler that builds fully static RISC-V64 binaries for zkVMs.

Motivation

Bflat targets zkVMs with a limited RISC-V64 instruction subset — no floating point, no compressed instructions, no operating system. Many parts of the .NET runtime are replaced by link-time modules (nofp, pal, rhp, tls, rng_stupid, ...), and each of those replacements needs dedicated verification. This suite exercises the compiler and every runtime module in isolation, as well as end-to-end scenarios up to stateless Ethereum block execution on Zisk.

Prerequisites

• Test Environment sources checked out next to this repository:

  workdir/
  ├── bflat-ts/
  └── test-environment/
  

• Docker (used both to run the bflat compiler image and, optionally, to run the whole suite in a container).
• ziskemu for running compiled binaries.

Running

The easiest way, given the folder structure above:

./scripts/run.sh guess

Useful options:

Option	Description
--cfg=<CFG>	Configuration to use (localhost by default, see conf/run.conf.*)
--bflat-image=<IMAGE>	Override the bflat Docker image (default: the image pinned in bflat-ts/lib/tsapi_bflat.h)
--nethermind-rev=<REV>	Pin the Nethermind revision (branch/tag/SHA) used by ZiskGuest tests; latest commit if omitted

Any other option is passed through to TE's dispatcher.sh — for example, --tester-run=bflat-ts/simple to run a single package. See ./scripts/run.sh --help for the full list.

To build and run the suite inside a Docker container (see scripts/docker/build/Dockerfile):

./scripts/run.sh docker guess

Test packages

Package	Description
simple	Simple bflat build tests
args	Main() argument variations
nofp	Floating-point stubs (nofp module)
pal	Platform Abstraction Layer (pal) stubs
rhp	Runtime Heap Platform (rhp) stubs
rng	Random number generation (rng_stupid)
tls	Thread-local storage (tls + rhp thread statics)
tls_stress	TLS/TSS slot overflow and independence
dispatch	Interface and virtual dispatch
dispatch_stress	Interface and virtual dispatch stress (t5 register clobber)
generics	Generic types and collections
gvm	Generic Virtual Method / TypeLoader crash patterns (Comparer<T>.Default)
exception_handler	Managed exception handler (ZkvmThrow)
format	Number and string formatting beyond basic cases
memory	Heap allocator correctness under grow and large allocations
build_perf	Build-performance tests — compile time measurement
run_perf	Run-performance tests — startup steps analysis under ziskemu
zisk_guest	Nethermind ZiskGuest integration — stateless block execution on Zisk

The bflat Docker image can also be overridden per-test with the bflat_image test parameter, or globally with the TS_BFLAT_IMAGE environment variable.

Expected results (TRC)

Expected test results are tracked in the Testing Results Comparator database at conf/trc.xml. To generate a TRC report:

./scripts/trc.sh

License

MIT License. Copyright (C) 2025-2026 Demerzel Solutions Limited (Nethermind).

Contributing

Contributions are welcome! Please open an issue or a pull request on GitHub.