Add release notes (#9771)

RELEASES.md

@@ -4,8 +4,90 @@ Unreleased.
 
 ### Added
 
+* The ISLE DSL used for Cranelift now has a first-class `bool` type.
+  [#9593](https://github.com/bytecodealliance/wasmtime/pull/9593)
+
+* Cranelift now supports a new single-pass register allocator designed for
+  compile-time performance (unlike the current default which is optimized for
+  runtime-of-generated-code performance).
+  [#9611](https://github.com/bytecodealliance/wasmtime/pull/9611)
+
+* The `wasmtime` crate now natively supports the `wasm-wave` crate and its
+  encoding of component value types.
+  [#8872](https://github.com/bytecodealliance/wasmtime/pull/8872)
+
+* A `Module` can now be created from an already-open file.
+  [#9571](https://github.com/bytecodealliance/wasmtime/pull/9571)
+
+* A new default-enabled crate feature, `signals-based-traps`, has been added to
+  the `wasmtime` crate. When disabled then runtime signal handling is not
+  required by the host. This is intended to help with future effort to port
+  Wasmtime to more platforms.
+  [#9614](https://github.com/bytecodealliance/wasmtime/pull/9614)
+
+* Linear memories may now be backed by `malloc` in certain conditions when guard
+  pages are disabled, for example.
+  [#9614](https://github.com/bytecodealliance/wasmtime/pull/9614)
+  [#9634](https://github.com/bytecodealliance/wasmtime/pull/9634)
+
+* Wasmtime's `async` feature no longer requires `std`.
+  [#9689](https://github.com/bytecodealliance/wasmtime/pull/9689)
+
+* The buffer and budget capacity of `OutgoingBody` in `wasmtime-wasi-http` are
+  now configurable.
+  [#9670](https://github.com/bytecodealliance/wasmtime/pull/9670)
+
 ### Changed
 
+* Wasmtime's external and internal distinction of "static" and "dynamic"
+  memories has been refactored and reworded. All options are preserved but
+  exported under different names with improved documentation about how they all
+  interact with one another. (and everything should be easier to understand)
+  [#9545](https://github.com/bytecodealliance/wasmtime/pull/9545)
+
+* Each `Store<T>` now caches a single fiber stack in async mode to avoid
+  allocating/deallocating if the store is used multiple times.
+  [#9604](https://github.com/bytecodealliance/wasmtime/pull/9604)
+
+* Linear memories now have a 32MiB guard region at the end instead of a 2GiB
+  guard region by default.
+  [#9606](https://github.com/bytecodealliance/wasmtime/pull/9606)
+
+* Wasmtime will no longer validate dependencies between WebAssembly features,
+  instead delegating this work to `wasmparser`'s validator.
+  [#9623](https://github.com/bytecodealliance/wasmtime/pull/9623)
+
+* Cranelift's `isle-in-source-tree` feature has been re-worked as an environment
+  variable.
+  [#9633](https://github.com/bytecodealliance/wasmtime/pull/9633)
+
+* Wasmtime's minimum supported Rust version is now 1.81.
+  [#9692](https://github.com/bytecodealliance/wasmtime/pull/9692)
+
+* Synthetic types in DWARF are now more efficiently represented.
+  [#9700](https://github.com/bytecodealliance/wasmtime/pull/9700)
+
+* Debug builtins on Windows are now exported correctly.
+  [#9706](https://github.com/bytecodealliance/wasmtime/pull/9706)
+
+* Documentation on `Config` now clarifies that defaults of some options may
+  differ depending on the selected target or compiler depending on features
+  supported.
+  [#9705](https://github.com/bytecodealliance/wasmtime/pull/9705)
+
+* Wasmtime's error-related types now all unconditionally implement the `Error`
+  trait, even in `#[no_std]` mode.
+  [#9702](https://github.com/bytecodealliance/wasmtime/pull/9702)
+
+### Fixed
+
+* Field type matching for subtyping with wasm GC has been fixed.
+  [#9724](https://github.com/bytecodealliance/wasmtime/pull/9724)
+
+* Native unwind info generated for s390x has been fixed in the face of tail
+  calls.
+  [#9725](https://github.com/bytecodealliance/wasmtime/pull/9725)
+
 --------------------------------------------------------------------------------
 
 Release notes for previous releases of Wasmtime can be found on the respective