Add linker options for hotpatching on ARM64 kernel driver #5444
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Add linker options for hotpatching on ARM64 kernel driver. Enables runtime hotpatching capabilities for the MSQuic kernel driver (msquic.sys) in Release|ARM64 builds by adding the necessary linker flags to msquic.kernel.vcxproj. Background Currently, ARM64 releases of msquic.sys do not support runtime hotpatching due to missing linker options required for ARM64 hotpatch operations. This limitation prevents in-memory updates for ARM64 deployments and affects compatibility with ARM64 systems that depend on hotpatch-enabled drivers. Changes Adds the following linker flags to the Release|ARM64 configuration: /hotpatchcompatible /profile /incremental:no - Generates PDB records for Vulcan compatibility and enables hotpatch-compatible linking /PDBINJECT:MAPFILE - Injects map file information into PDB for ARM64-native hotpatch methodology (replaces x64's /FUNCTIONPADMIN:6) Impact - Production Deployments: Enables in-memory hotpatching for production MSQuic kernel driver updates on ARM64 systems - Component Compatibility: Ensures compatibility with ARM64 components requiring hotpatch-enabled drivers - Operational Benefits: Reduces downtime by supporting runtime driver updates without system restarts on ARM64 platforms Technical Details ARM64 hotpatching uses map file injection rather than function padding. The /PDBINJECT:MAPFILE flag creates a function layout map that enables the hotpatch loader to create proper trampolines for ARM64 instruction sets, allowing seamless redirection from baseline to patch binary at runtime.
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #5444 +/- ##
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+ Coverage 84.61% 84.73% +0.12%
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Files 59 59
Lines 18600 18600
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+ Hits 15738 15761 +23
+ Misses 2862 2839 -23 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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Description
Add linker options for hotpatching on ARM64 kernel driver.
Enables runtime hotpatching capabilities for the MSQuic kernel driver (msquic.sys) in Release|ARM64 builds by adding the necessary linker flags to msquic.kernel.vcxproj.
Background
Currently, ARM64 releases of msquic.sys do not support runtime hotpatching due to missing linker options required for ARM64 hotpatch operations. This limitation prevents in-memory updates for ARM64 deployments and affects compatibility with ARM64 systems that depend on hotpatch-enabled drivers.
Changes
Adds the following linker flags to the Release|ARM64 configuration:
/hotpatchcompatible /profile /incremental:no - Generates PDB records for Vulcan compatibility and enables hotpatch-compatible
/PDBINJECT:MAPFILE - Injects map file information into PDB for ARM64-native hotpatch methodology (replaces x64's /FUNCTIONPADMIN:6)
Impact
Technical Details
ARM64 hotpatching uses map file injection rather than function padding. The /PDBINJECT:MAPFILE flag creates a function layout map that enables the hotpatch loader to create proper trampolines for ARM64 instruction sets, allowing seamless redirection from baseline to patch binary at runtime.
Testing
Completed Verification
✅ Visual Studio Build: Confirmed that locally built msquic.sys for ARM64 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
Download Release-winkernel-windows-2022-ARM64-schannel artifact from GitHub Actions
Verify binary contains required hotpatch metadata
Perform runtime hotpatch loading test with CI-generated binary
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.