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Support loading cDAC from SOS installations - #5874
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…ntract (#129456) > [!NOTE] > This PR was authored with assistance from GitHub Copilot. ## Summary Fixes a cDAC `GetCodeHeaderData` failure that surfaced as `Unable to get codeHeader information` when SOS ran `!clru` against an IL stub MethodDesc on **Windows x86** with cDAC enabled (the new default behavior on .NET 11 introduced by [dotnet/diagnostics#5874](dotnet/diagnostics#5874)). The CI failure that motivated this is `SOSMethodTests.VarargPInvokeInteropMD` on x86 in dotnet/diagnostics: `!IP2MD` returned the IL stub MethodDesc correctly, but the immediate follow-up `!clru <MD>` printed only `Unable to get codeHeader information`. x64 / arm64 / .NET 8/9/10 were unaffected. ## Root cause x86 uses a fundamentally different GC info encoding from every other architecture: the legacy bit-packed `InfoHdr` byte-stream format from [`src/coreclr/vm/gc_unwind_x86.inl`](https://github.com/dotnet/runtime/blob/main/src/coreclr/vm/gc_unwind_x86.inl) and [`src/coreclr/inc/gcdecoder.cpp`](https://github.com/dotnet/runtime/blob/main/src/coreclr/inc/gcdecoder.cpp) (`USE_GC_INFO_DECODER` is defined for every target except x86, see `eetwain.h:34`). The cDAC `GCInfo` contract registered IGCInfo implementations for X64/Arm64/Arm/LoongArch64/RiscV64 but **not** X86 -- so on x86 it fell through to `default(GCInfo)` and threw `NotImplementedException` from the interface's default `DecodePlatformSpecificGCInfo`. Any SOS path that needed method size on x86 (`!clru`, `GetCodeHeaderData`, `GetMethodRegionInfo`) failed. ## Approach The cDAC already had a substantial x86 `InfoHdr` decoder under `Contracts/StackWalk/Context/X86/GCInfoDecoding/`, used by the x86 stack walker. Rather than write a parallel decoder, this PR **relocates** that existing decoder under the `GCInfo` contract so there is **one canonical x86 GC info implementation** shared between SOS callers and the stack walker -- mirroring how the other architectures' decoders are structured. ## Changes * **Move** `Contracts/StackWalk/Context/X86/GCInfoDecoding/*` → `Contracts/GCInfo/X86/*` (6 files, tracked as renames). Rename namespace `StackWalkHelpers.X86` → `GCInfoHelpers.X86`. * **Rename** the moved class `GCInfo` → `X86GCInfo` to avoid collision with the empty `Contracts.GCInfo` IGCInfo fallback struct. * Make `relativeOffset` ctor arg optional. Implement `IGCInfoDecoder` directly on `X86GCInfo`: `GetCodeLength` / `GetStackBaseRegister` / `GetSizeOfStackParameterArea` are wired up. `GetInterruptibleRanges` and `EnumerateLiveSlots` throw `NotSupportedException` (future work, needed for `!gcroot` / `!clrstack -l` etc.). * Add `GCInfoX86_1` IGCInfo for x86; register it in `CoreCLRContracts.cs` for `RuntimeInfoArchitecture.X86`. * Update `ExecutionManagerCore.GetStackParameterSize` to delegate to `IGCInfo.GetSizeOfStackParameterArea` (one source of truth). * `X86Unwinder` continues to construct `X86GCInfo` directly because it needs offset-bound state (`IsInProlog` / `IsInEpilog` / `PushedArgSize`) not exposed through `IGCInfoDecoder`. ## Tests * New `VarargPInvoke_GetCodeHeaderDataForILStub_ReturnsMethodSize` regression test in `cdac/tests/DumpTests/StackWalkDumpTests.cs` -- asserts the IL stub path returns S_OK with non-zero `MethodSize`. Runs against the existing cdac-dump-helix `windows_x86` matrix on every PR (no pipeline changes needed). * Existing 2509 cDAC unit tests still pass. * Validated end-to-end against `SOSMethodTests.VarargPInvokeInteropMD` x86 .NET 11prev6 cDAC: 4/4 pass after this fix; failed before. ## Docs * `docs/design/datacontracts/GCInfo.md` -- intro now reflects partial x86 support; `GetSizeOfStackParameterArea` API documented; per-method status notes for x86. * `docs/design/datacontracts/StackWalk.md` -- x86 section points at the consolidated decoder location and explains how it's shared. ## Out of scope (future work) * `GetInterruptibleRanges` and `EnumerateLiveSlots` for x86. The underlying transition data is decoded but the adapter to the cDAC `IGCInfoDecoder` shape is not wired up yet. This is what's needed to unblock `!gcroot`, `!clrstack -l`, `!pe` on x86 cDAC. The two pre-existing `[SkipOnArch("x86", "GCInfo decoder does not support x86")]` markers in `StackReferenceDumpTests.cs` should become removable once that lands. --------- Co-authored-by: Max Charlamb <maxcharlamb@microsoft.com> Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Pull request overview
This PR updates SOS/tool packaging and runtime-loading behavior to bundle and preferentially load the cDAC (mscordaccore_universal) from diagnostics tool installations, with a default policy for .NET 11+ and a new tri-state user control surface.
Changes:
- Add cDAC discovery/loading paths across native SOS, SOS.Hosting, and ClrMD runtime creation (including contract descriptor plumbing via
ICLRContractLocator). - Introduce an asset/layout resolver (
IHostAssetResolver+SOSPackageLayout) so tools consistently locate native binaries (including bundled cDAC) regardless of host. - Update packaging/build logic to optionally bundle cDAC into tool packages and adjust tests/scripts for current SOS output differences.
Reviewed changes
Copilot reviewed 34 out of 34 changed files in this pull request and generated 3 comments.
Show a summary per file
| File | Description |
|---|---|
| src/tests/SOS.UnitTests/SOS.cs | Updates test skip conditions (notably Win-x86) for tracked regression coverage. |
| src/tests/SOS.UnitTests/Scripts/StackAndOtherTests.script | Makes stack verification tolerant to shifted source line numbers. |
| src/SOS/Strike/util.cpp | Requests cDAC-capable CLR data process in the main SOS load path; whitespace cleanup. |
| src/SOS/Strike/platform/runtimeimpl.h | Adds cDAC path/process members and policy/helpers to native Runtime. |
| src/SOS/Strike/platform/runtimeimpl.cpp | Implements cDAC path resolution (next to SOS), policy, IXCLRDataProcess creation, and contract descriptor lookup. |
| src/SOS/Strike/platform/datatarget.h | Extends DataTarget to implement ICLRContractLocator. |
| src/SOS/Strike/platform/datatarget.cpp | Implements ICLRContractLocator::GetContractDescriptor and QueryInterface wiring. |
| src/SOS/Strike/clrma/managedanalysis.cpp | Improves tracing when runtime-based DAC retrieval fails and falls back. |
| src/SOS/SOS.Package/SOS.Symbol.Package.csproj | Adds single-RID packing support via conditional symbol inclusion. |
| src/SOS/SOS.Package/SOS.Package.csproj | Ensures dotnet run for manifest generation uses the active configuration. |
| src/SOS/SOS.Package/GenerateManifest/Directory.Build.targets | Shields file-based app build by preventing repo targets import (intentionally empty). |
| src/SOS/SOS.Package/GenerateManifest/Directory.Build.props | Shields file-based app build by preventing repo props import (intentionally empty). |
| src/SOS/SOS.InstallHelper/SOS.InstallHelper.csproj | Links shared SOSPackageLayout implementation into InstallHelper. |
| src/SOS/SOS.InstallHelper/InstallHelper.cs | Switches native/managed source path resolution to SOSPackageLayout. |
| src/SOS/SOS.Hosting/SOSPackageLayout.cs | Defines package-relative layout rules for native vs managed SOS assets. |
| src/SOS/SOS.Hosting/SOSLibrary.cs | Uses IHostAssetResolver for native binary location; updates ISOSModule semantics/comments. |
| src/SOS/SOS.Hosting/SOS.Hosting.csproj | Removes InstallHelper project reference (no longer needed). |
| src/SOS/SOS.Hosting/RuntimeWrapper.cs | Prefers cDAC for IXCLRDataProcess path; refactors DAC/cDAC load handling. |
| src/SOS/SOS.Hosting/HostAssetResolver.cs | New global service that resolves native binaries directory and cDAC path. |
| src/SOS/SOS.Extensions/HostServices.cs | Removes unnecessary unsafe modifier; continues to expose ISOSModule data. |
| src/sos-packaging.props | Reworks packaging inputs/conditions, adds SingleTargetRidPackage/PackageWithCDac semantics. |
| src/Microsoft.Diagnostics.ExtensionCommands/Host/RuntimesCommand.cs | Replaces previous flags with tri-state `--usecdac true |
| src/Microsoft.Diagnostics.ExtensionCommands/Host/CommandFormatHelpers.cs | Updates settings output to reflect tri-state cDAC policy. |
| src/Microsoft.Diagnostics.DebugServices/ISettingsService.cs | Replaces prior cDAC flags with bool? UseCDac and documents policy semantics. |
| src/Microsoft.Diagnostics.DebugServices/IRuntime.cs | Clarifies DAC vs cDAC path responsibilities and nullability for cDAC. |
| src/Microsoft.Diagnostics.DebugServices/IHostAssetResolver.cs | New contract for resolving host-native asset locations (including cDAC). |
| src/Microsoft.Diagnostics.DebugServices.Implementation/ServiceManager.cs | Removes SOS.InstallHelper from default assemblies list for extension loading. |
| src/Microsoft.Diagnostics.DebugServices.Implementation/RuntimeProvider.cs | Adds signature-verification override for the trusted bundled cDAC path. |
| src/Microsoft.Diagnostics.DebugServices.Implementation/Runtime.cs | Implements cDAC policy, uses host resolver for cDAC path, and prefers cDAC for ClrMD runtime creation. |
| src/Microsoft.Diagnostics.DebugServices.Implementation/Host.cs | Updates settings storage to bool? UseCDac. |
| src/dbgshim/pkg/Microsoft.Diagnostics.DbgShim.props | Optionally packages cDAC next to dbgshim when enabled. |
| eng/Versions.props | Defaults PackageWithCDac=true on preview branches unless overridden. |
| eng/InstallNativePackages.targets | Downloads/stages cDAC transport pack content when PackageWithCDac=true. |
| eng/CdacPackageItems.props | Removes prior per-RID cDAC transport pack itemization (now in targets). |
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| ExtDbgOut("GetCDacFilePath: dladdr failed to locate the sos module\n"); | ||
| return nullptr; | ||
| } | ||
| strcpy_s(szSOSModulePath.GetPtr(), MAX_LONGPATH, info.dli_fname); |
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Comment on lines
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| // Prefer the cDAC for the data-access (IXCLRDataProcess) path when the runtime policy | ||
| // selects it (GetCDacFilePath returns non-null); fall back to the in-box DAC otherwise. | ||
| // The ICorDebug/DBI path (CreateCorDebugProcess) always uses the in-box DAC. The flags | ||
| // parameter is retained for the native IRuntime contract but no longer consulted here. | ||
| if (_cdacDataProcess == IntPtr.Zero) |
steveisok
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Jun 17, 2026
max-charlamb
previously approved these changes
Jun 17, 2026
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Cover diagnostics@dc90e42 (score 5): Support loading cDAC from SOS installations (dotnet/diagnostics#5874). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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…ntract (#129456) > [!NOTE] > This PR was authored with assistance from GitHub Copilot. ## Summary Fixes a cDAC `GetCodeHeaderData` failure that surfaced as `Unable to get codeHeader information` when SOS ran `!clru` against an IL stub MethodDesc on **Windows x86** with cDAC enabled (the new default behavior on .NET 11 introduced by [dotnet/diagnostics#5874](dotnet/diagnostics#5874)). The CI failure that motivated this is `SOSMethodTests.VarargPInvokeInteropMD` on x86 in dotnet/diagnostics: `!IP2MD` returned the IL stub MethodDesc correctly, but the immediate follow-up `!clru <MD>` printed only `Unable to get codeHeader information`. x64 / arm64 / .NET 8/9/10 were unaffected. ## Root cause x86 uses a fundamentally different GC info encoding from every other architecture: the legacy bit-packed `InfoHdr` byte-stream format from [`src/coreclr/vm/gc_unwind_x86.inl`](https://github.com/dotnet/runtime/blob/main/src/coreclr/vm/gc_unwind_x86.inl) and [`src/coreclr/inc/gcdecoder.cpp`](https://github.com/dotnet/runtime/blob/main/src/coreclr/inc/gcdecoder.cpp) (`USE_GC_INFO_DECODER` is defined for every target except x86, see `eetwain.h:34`). The cDAC `GCInfo` contract registered IGCInfo implementations for X64/Arm64/Arm/LoongArch64/RiscV64 but **not** X86 -- so on x86 it fell through to `default(GCInfo)` and threw `NotImplementedException` from the interface's default `DecodePlatformSpecificGCInfo`. Any SOS path that needed method size on x86 (`!clru`, `GetCodeHeaderData`, `GetMethodRegionInfo`) failed. ## Approach The cDAC already had a substantial x86 `InfoHdr` decoder under `Contracts/StackWalk/Context/X86/GCInfoDecoding/`, used by the x86 stack walker. Rather than write a parallel decoder, this PR **relocates** that existing decoder under the `GCInfo` contract so there is **one canonical x86 GC info implementation** shared between SOS callers and the stack walker -- mirroring how the other architectures' decoders are structured. ## Changes * **Move** `Contracts/StackWalk/Context/X86/GCInfoDecoding/*` → `Contracts/GCInfo/X86/*` (6 files, tracked as renames). Rename namespace `StackWalkHelpers.X86` → `GCInfoHelpers.X86`. * **Rename** the moved class `GCInfo` → `X86GCInfo` to avoid collision with the empty `Contracts.GCInfo` IGCInfo fallback struct. * Make `relativeOffset` ctor arg optional. Implement `IGCInfoDecoder` directly on `X86GCInfo`: `GetCodeLength` / `GetStackBaseRegister` / `GetSizeOfStackParameterArea` are wired up. `GetInterruptibleRanges` and `EnumerateLiveSlots` throw `NotSupportedException` (future work, needed for `!gcroot` / `!clrstack -l` etc.). * Add `GCInfoX86_1` IGCInfo for x86; register it in `CoreCLRContracts.cs` for `RuntimeInfoArchitecture.X86`. * Update `ExecutionManagerCore.GetStackParameterSize` to delegate to `IGCInfo.GetSizeOfStackParameterArea` (one source of truth). * `X86Unwinder` continues to construct `X86GCInfo` directly because it needs offset-bound state (`IsInProlog` / `IsInEpilog` / `PushedArgSize`) not exposed through `IGCInfoDecoder`. ## Tests * New `VarargPInvoke_GetCodeHeaderDataForILStub_ReturnsMethodSize` regression test in `cdac/tests/DumpTests/StackWalkDumpTests.cs` -- asserts the IL stub path returns S_OK with non-zero `MethodSize`. Runs against the existing cdac-dump-helix `windows_x86` matrix on every PR (no pipeline changes needed). * Existing 2509 cDAC unit tests still pass. * Validated end-to-end against `SOSMethodTests.VarargPInvokeInteropMD` x86 .NET 11prev6 cDAC: 4/4 pass after this fix; failed before. ## Docs * `docs/design/datacontracts/GCInfo.md` -- intro now reflects partial x86 support; `GetSizeOfStackParameterArea` API documented; per-method status notes for x86. * `docs/design/datacontracts/StackWalk.md` -- x86 section points at the consolidated decoder location and explains how it's shared. ## Out of scope (future work) * `GetInterruptibleRanges` and `EnumerateLiveSlots` for x86. The underlying transition data is decoded but the adapter to the cDAC `IGCInfoDecoder` shape is not wired up yet. This is what's needed to unblock `!gcroot`, `!clrstack -l`, `!pe` on x86 cDAC. The two pre-existing `[SkipOnArch("x86", "GCInfo decoder does not support x86")]` markers in `StackReferenceDumpTests.cs` should become removable once that lands. --------- Co-authored-by: Max Charlamb <maxcharlamb@microsoft.com> Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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Bundle the cDAC into diagnostics tool packages and implement interim loading policy for DAC/cDAC:
UseCDac(null= default policy described above, true=force, false=never) with--usecdac true|false|policy**DataTargetimplementsICLRContractLocatorand stores resolved contract descriptor address for cDAC initializationsos-packaging.propscleanup to allow any arch packaging;PackageWithCDac=trueby default on main branch so all platforms (win-x64/x86/arm64, linux-*, osx-*) bundle cDAC alongside sos.