Wasmtime GitHub notifications bot (Apr 15 2026 at 17:39): Wasmtime GitHub notifications bot (Apr 15 2026 at 17:39):alexcrichton opened PR #13109 from alexcrichton:remove-system-interface to bytecodealliance:main:
This commit removes the
system-interfacedependency fromwasi-common, reimplementing necessary functionality within the crate itself as appropriate. The goal of this commit is to trim our dependency tree. Thesystem-interfacecrate has not received an update in over a year and continues to pull in an olderrustixdependency for example. Additionally I've personally found it confusing and surprising in the past to trace through all the layers of abstractions fromwasmtime-wasito the OS, and I'd like to start slimming this down to be more local within Wasmtime rather than depending on a tree of crates.The
system-interfacecrate is a relatively thin wrapper aroundcap-std-style crates providing a platform-agnostic API. This sometimes fits what WASI wants, and sometimes doesn't. For example all reads/writes to files within WASI currently require that Wasmtime maintains a file cursor itself meaning that the underlying OS file cursor doesn't actually matter. Reads and writes through thesystem-interfaceabstraction, however, keep the cursor up-to-date to have the same semantics across Unix and Windows which differ in the behavior of the underlying syscalls. This is unnecessarily adds overhead to Wasmtime's implementation of these APIs where they're otherwise not required.Effectively
system-interfaceis not receiving much maintenance (old dependency onrustixhas persisted for ~1 year), its an extra layer of abstraction to debug when issues arise, and its abstractions are not always the best fit for WASI's semantics meaning that it can add performance overhead. The replacement of inlining implementations within Wasmtime is not too too costly and, personally, I view as worth it.I'll note that this doesn't delete the
system-interfacecrate entirely. That would require removing it fromwasi-commonas well, which is the subject of #13108.<!--
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Wasmtime GitHub notifications bot (Apr 15 2026 at 17:39):alexcrichton requested wasmtime-wasi-reviewers for a review on PR #13109.
Wasmtime GitHub notifications bot (Apr 15 2026 at 17:39):alexcrichton requested dicej for a review on PR #13109.
Wasmtime GitHub notifications bot (Apr 15 2026 at 17:39):alexcrichton requested wasmtime-default-reviewers for a review on PR #13109.
Wasmtime GitHub notifications bot (Apr 15 2026 at 17:40):alexcrichton updated PR #13109.
Last updated: May 03 2026 at 22:13 UTC