SOS: activate cDAC through dbgshim

[hoyosjs]

Summary

Use dbgshim as SOS's only cDAC activation path. SOS supplies the runtime module and
data target, receives a cDAC-backed IXCLRDataProcess, and registers it with ClrMD.

Remove runtime-version checks from cDAC selection. The cDAC now determines whether it
supports a target through contract validation.

Policy

Policy	Behavior
PreferCDac	Try cDAC, then allow DAC fallback
OnlyUseCDac	Require cDAC; do not fall back
UseLegacyDac	Use the DAC without trying cDAC

runtimes --usecdac sets the policy for the SOS session.

Design

• CreateClrDataProcessFromCDac always requests CDacOnly from dbgshim, so a
  successful result is known to be cDAC-backed.
• Runtime owns and caches the cDAC process, activation HRESULT, and lifetime.
• RuntimeWrapper is the COM projection of Runtime used by native SOS; it does not
  independently activate cDAC.
• Native SOS without managed hosting uses the equivalent dbgshim activation path.
• ClrMD receives an activated cDAC interface through AddLoadedRuntime; ClrMD only
  loads the legacy DAC fallback.
• dbgshim is packaged for every SOS RID. cDAC is packaged for every SOS RID when
  enabled.

[Copilot]

Pull request overview

Routes SOS cDAC activation through dbgshim with policy-based DAC fallback and ClrMD runtime registration.

Changes:

• Adds native and managed dbgshim activation paths.
• Centralizes cDAC policy handling and removes direct cDAC loading.
• Registers activated runtimes with ClrMD.

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Review summary
src/SOS/Strike/util.cpp	Reviewed; no final comments.
src/SOS/Strike/platform/runtimeimpl.h	Reviewed; no final comments.
src/SOS/Strike/platform/runtimeimpl.cpp	Moderate: restore CLR notification setup for live targets.
src/SOS/Strike/clrma/managedanalysis.cpp	Reviewed; no final comments.
src/SOS/SOS.Hosting/RuntimeWrapper.cs	Moderate: honor cDAC environment gates while preserving forced-policy behavior.
src/SOS/SOS.Hosting/ICLRDebuggingPolicy.cs	Reviewed; no final comments.
src/SOS/SOS.Hosting/ICLRDebugging.cs	Reviewed; no final comments.
src/SOS/SOS.Hosting/ClrDataProcessActivator.cs	Moderate: release retained wrappers and services after failed activation and teardown.
src/SOS/inc/runtime.h	Reviewed; no final comments.
src/Microsoft.Diagnostics.TestHelpers/TestHost/TestDataWriter.cs	Reviewed; no final comments.
src/Microsoft.Diagnostics.DebugServices/IRuntime.cs	Reviewed; no final comments.
src/Microsoft.Diagnostics.DebugServices/IClrDataProcessActivator.cs	Reviewed; no final comments.
src/Microsoft.Diagnostics.DebugServices.Implementation/Runtime.cs	Reviewed; no final comments.

Suppressed comments (1)

src/SOS/Strike/platform/runtimeimpl.cpp:546

• The new CDacOnly flag is not considered by GetClrDataProcess; the failure and fallback checks below consult only s_cdacLoadPolicy. A caller passing CDacOnly while the global policy is Default therefore falls back to the DAC when dbgshim declines, despite the flag's documented no-fallback semantics (and the managed wrapper treating it as forced). Include the flag in both the activation decision and the fallback suppression checks.

            HRESULT hr = CreateClrDataProcessWithDbgShim(&m_cdacDataProcess);
            if (FAILED(hr) && s_cdacLoadPolicy == CDacLoadPolicy::UseCDac)
            {
                *ppClrDataProcess = nullptr;
                return hr;

---

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[Copilot]

Pull request overview

Copilot reviewed 19 out of 20 changed files in this pull request and generated 2 comments.

Suppressed comments (1)

src/SOS/SOS.Hosting/ClrDataProcessActivator.cs:188

• This stores the creator reference returned by CLRCreateInstance, but ICLRDebugging calls SuppressRelease(), so neither the wrapper nor the global service ever releases it. The same reference is leaked on the policy-setup failure path. Make the activator disposable and release the shared interface at global-service teardown, while also releasing it before returning from initialization failures (the existing dbgshim tests explicitly balance these wrappers with Release()).

                ICLRDebugging clrDebugging = ICLRDebugging.Create(punk);
                hr = SetCDacLoadPolicy(clrDebugging, DbgShimCDacLoadPolicy.CDacOnly);
                if (!hr)
                {
                    Trace.TraceError($"ClrDataProcessActivator: SetCDacLoadPolicy(CDacOnly) failed (hr={hr:x8}).");
                    return null;
                }
                _clrDebugging = clrDebugging;