[release-notes] .NET Runtime in .NET 11 RC 1

release-notes/11.0/preview/rc1/runtime.md

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+# .NET Runtime in .NET 11 RC 1 - Release Notes
+
+.NET 11 RC 1 includes new runtime platform and diagnostics capabilities:
+
+- [CoreCLR support for linux-bionic](#coreclr-support-for-linux-bionic)
+- [In-process crash reporting on Unix](#in-process-crash-reporting-on-unix)
+- [Half operations use FP16 hardware instructions](#half-operations-use-fp16-hardware-instructions)
+- [Bug fixes](#bug-fixes)
+- [Community contributors](#community-contributors)
+
+.NET Runtime updates in .NET 11:
+
+- [What's new in the .NET 11 runtime](https://learn.microsoft.com/dotnet/core/whats-new/dotnet-11/runtime)
+
+## CoreCLR support for linux-bionic
+
+CoreCLR is now enabled for `linux-bionic-arm64` and `linux-bionic-x64`, including Termux scenarios on Android ([dotnet/runtime #131115](https://github.com/dotnet/runtime/pull/131115)). The linux-bionic AppHost pack now includes `singlefilehost`, so self-contained single-file applications use the expected bundled host instead of falling back to an apphost that cannot launch the bundle.
+
+The build selects CoreCLR alongside Mono, the libraries, host, and packs on the supported linux-bionic architectures. NativeAOT remains the fallback for linux-bionic architectures where CoreCLR isn't enabled.
+
+## In-process crash reporting on Unix
+
+The in-process crash reporter is now available on Linux and macOS through the existing crash-report settings ([dotnet/runtime #131410](https://github.com/dotnet/runtime/pull/131410)). When `DOTNET_DbgEnableMiniDump` isn't enabled, setting `DOTNET_EnableCrashReport=1` or `DOTNET_EnableCrashReportOnly=1` selects the in-process reporter. Existing createdump behavior remains in place when minidumps are enabled.
+
+Community contributions extended the in-process reporter across the remaining Unix platforms and added s390x support ([dotnet/runtime #131604](https://github.com/dotnet/runtime/pull/131604), [dotnet/runtime #131796](https://github.com/dotnet/runtime/pull/131796)). Thank you [@am11](https://github.com/am11) and [@saitama951](https://github.com/saitama951) for these contributions!
+
+## Half operations use FP16 hardware instructions
+
+The JIT now uses hardware FP16 instructions for `System.Half` arithmetic and conversions when the processor supports them ([dotnet/runtime #130512](https://github.com/dotnet/runtime/pull/130512)). On x64, arithmetic uses AVX10.1 while conversions between `Half` and `float` can use F16C. On Arm64, arithmetic uses the optional FP16 instruction set, while conversions between `Half` and `float` or `double` use baseline Arm64 instructions.
+
+The optimization requires no application changes and preserves the existing ABI representation of `Half`.
+
+<!-- Filtered features (significant engineering work, but too niche for standalone release-note sections):
+  - On-demand in-process crash-report generation (dotnet/runtime #131220): Internal infrastructure for native fatal-error handlers, not a public user-facing capability.
+  - WebAssembly RyuJIT and ReadyToRun fixes: Important stabilization work, but the individual changes are architecture-specific fixes rather than a new RC 1 capability.
+  - cDAC debugger contract expansion: Primarily diagnostics-tool implementation work without a broad end-user workflow to announce in RC 1.
+  - Arm64 SVE constant vectors and masks: Valuable architecture enablement, but limited to specialized SVE code generation and not supported by RC 1 benchmark evidence.
+-->
+
+## Bug fixes
+
+- **Garbage collection**
+  - `GC.GetTotalMemory` no longer reports negative values when regions are enabled ([dotnet/runtime #130888](https://github.com/dotnet/runtime/pull/130888)).
+  - `GC.GetTotalAllocatedBytes` remains monotonic with Dynamic Adaptation To Application Sizes (DATAS) under Server GC ([dotnet/runtime #131069](https://github.com/dotnet/runtime/pull/131069)).
+- **Hosting**
+  - `Environment.GetCommandLineArgs()[0]` now reports the host invocation name instead of a rewritten path in affected hosting scenarios ([dotnet/runtime #131671](https://github.com/dotnet/runtime/pull/131671)).
+  - Native exception handling in external shared libraries works correctly on macOS ([dotnet/runtime #130693](https://github.com/dotnet/runtime/pull/130693)).
+- **Runtime diagnostics**
+  - In-process crash reports no longer assert while processing certain stack frames ([dotnet/runtime #131273](https://github.com/dotnet/runtime/pull/131273)).
+  - Concurrent in-process crash-report requests are serialized to protect shared reporting state ([dotnet/runtime #130436](https://github.com/dotnet/runtime/pull/130436)).
+- **Type system and interop**
+  - Loading recursive nullable types that implement static abstract interfaces no longer crashes on Linux ([dotnet/runtime #130088](https://github.com/dotnet/runtime/pull/130088)).
+  - The `ComWrappers` runtime-callable-wrapper cache is partitioned into per-processor buckets, reducing contention between native-to-managed transitions and finalization ([dotnet/runtime #132033](https://github.com/dotnet/runtime/pull/132033)).
+
+## Community contributors
+
+Thank you contributors! ❤️
+
+- [@abhishekabhi73cc-design](https://github.com/dotnet/runtime/pulls?q=is%3Apr+is%3Amerged+author%3Aabhishekabhi73cc-design)
+- [@am11](https://github.com/dotnet/runtime/pulls?q=is%3Apr+is%3Amerged+author%3Aam11)
+- [@saitama951](https://github.com/dotnet/runtime/pulls?q=is%3Apr+is%3Amerged+author%3Asaitama951)
+- [@Sergio0694](https://github.com/dotnet/runtime/pulls?q=is%3Apr+is%3Amerged+author%3ASergio0694)