Add linker options for hotpatching on x64 kernel driver #5437
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Add hotpatch support for x64 kernel driver Enable hotpatching capabilities for msquic.sys in Release|x64 builds. This allows SMBDirect and other components to use MSQuic artifacts with runtime hotpatching support enabled. - Enables function padding for Release|x64 configuration - Supports runtime hotpatching for production deployments These linker flags modifications meaning: - /hotpatchcompatible /profile /incremental:no This adds records to the PDB which lets vulcan understand the binary. - /FUNCTIONPADMIN:6 This adds padding needed for hotpatching on x64 binaries. The 6 bytes of padding on x64 are used by hpiload at patch load time to trampoline from the baseline binary to the patch binary.
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #5437 +/- ##
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- Coverage 85.90% 84.73% -1.18%
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Files 59 59
Lines 18600 18600
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- Hits 15979 15761 -218
- Misses 2621 2839 +218 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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Description
Add hotpatch support for Windows x64 kernel driver
This PR enables runtime hotpatching capabilities for the MSQuic kernel driver (msquic.sys) in Release|x64 builds by adding the necessary linker flags to msquic.kernel.vcxproj.
Background
Currently, production releases of msquic.sys do not support runtime hotpatching due to missing linker options and function padding required for x64 hotpatch operations. This limitation prevents in-memory updates and affects compatibility with components such as SMBDirect that depend on hotpatch-enabled drivers.
Changes
This PR adds the following linker flags to the Release|x64 configuration:
Impact
Technical Details
Testing
Completed Verification
✅ Visual Studio Build: Confirmed that locally built msquic.sys for x64 Release configuration contains all required hotpatch prerequisites.
✅ Hotpatch Loading: Successfully loaded and applied a hotpatch to the driver in memory during testing.
✅ GitHub Actions Pipeline: Verify that CI/CD-generated msquic.sys artifact maintain hotpatch compatibility
✅ Release Artifact Testing: Confirm that market-ready msquic.sys binary produced by GitHub pipelines support hotpatch operations
Validation Plan
✅https://github.com/microsoft/msquic/actions/runs/17618956151/job/50059433726?pr=5437
✅https://github.com/microsoft/msquic/actions/runs/17618956151/artifacts/3976994659
✅Successfully loaded and applied a hotpatch to the driver in memory during testing.
Documentation
No user-facing documentation changes required. This is an internal build configuration change that enables existing Windows hotpatch infrastructure. The functionality is transparent to end users and does not modify MSQuic APIs or behavior.