From e69fe212a38f8cfb4bbe0043444836ff2a382128 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Benjamin=20H=C3=B6glinger-Stelzer?= <nefarius@dhmx.at>
Date: Tue, 28 Jul 2026 01:06:19 +0200
Subject: [PATCH 1/2] Cache DMF libraries and build only the DmfU target

BuildDmf previously rebuilt the entire Dmf.sln (including unused
kernel-mode projects) on every CI run. Target only DmfU, which is what
the UMDF driver links, and cache DMF/Release/<platform> keyed on the
submodule commit plus runner ImageVersion so warm jobs can --skip BuildDmf.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 .github/workflows/build.yml | 22 +++++++++++++++++++++-
 build/Build.cs              |  7 +++++--
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index be49daba..7953d878 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -112,9 +112,29 @@ jobs:
           dotnet restore .\ControlApp\
           dotnet restore .\ipctest\
 
+      # DMF output is fully determined by the submodule commit and the runner toolchain.
+      # Skip the build entirely on a cache hit (x86 never builds DMF). No restore-keys: a
+      # partial match must never reuse libs built for a different commit or image.
+      - name: 'Resolve DMF submodule commit'
+        if: matrix.platform != 'x86'
+        id: dmf-sha
+        shell: pwsh
+        run: |
+          $sha = git rev-parse HEAD:DMF
+          echo "sha=$sha" >> $env:GITHUB_OUTPUT
+          Write-Output "DMF submodule commit $sha"
+
+      - name: 'Cache DMF libraries'
+        if: matrix.platform != 'x86'
+        id: dmf-cache
+        uses: actions/cache@v4
+        with:
+          path: DMF/Release/${{ matrix.platform }}
+          key: dmf-v1-${{ matrix.platform }}-${{ steps.dmf-sha.outputs.sha }}-${{ env.ImageVersion }}
+
       - name: 'Build'
         shell: cmd
-        run: .\build.cmd --target-platform ${{ matrix.platform }}
+        run: .\build.cmd --target-platform ${{ matrix.platform }} ${{ steps.dmf-cache.outputs.cache-hit == 'true' && '--skip BuildDmf' || '' }}
 
       - name: 'Publish ControlApp'
         if: matrix.platform == 'x64'
diff --git a/build/Build.cs b/build/Build.cs
index 1a3dc6c5..e3c15f6f 100644
--- a/build/Build.cs
+++ b/build/Build.cs
@@ -131,10 +131,13 @@ void InvokeSignTool(string arguments)
 
             foreach ((Configuration config, MSBuildTargetPlatform platform) in buildCombinations)
             {
-                Log.Information("Building DMF {Configuration} | {Platform}", config, platform);
+                // dshidmini is UMDF and links only DmfU.lib; skip the kernel-mode half of Dmf.sln.
+                // MSBuild resolves "DmfU" as a solution-level target and pulls in its dependencies
+                // (DmfUFramework, DmfUModules.Library, DmfUModules.Template, DmfUModules.Library.Tests).
+                Log.Information("Building DMF DmfU {Configuration} | {Platform}", config, platform);
                 MSBuildTasks.MSBuild(s => s
                     .SetTargetPath(DmfSolution)
-                    .SetTargets("Build")
+                    .SetTargets("DmfU")
                     .SetConfiguration(config)
                     .SetTargetPlatform(platform)
                     .SetMaxCpuCount(Environment.ProcessorCount)

From 4deb75ff685c789c91ed37acd2a504ebe46d63b5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Benjamin=20H=C3=B6glinger-Stelzer?= <nefarius@dhmx.at>
Date: Tue, 28 Jul 2026 01:14:34 +0200
Subject: [PATCH 2/2] Fix DMF cache key to capture runner ImageVersion

${{ env.ImageVersion }} reads the Actions env context, which does not
include runner process variables, so the key ended with an empty suffix.
Capture $env:ImageVersion in the resolve step instead.

Co-authored-by: Cursor <cursoragent@cursor.com>
---
 .github/workflows/build.yml | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 7953d878..6d37e410 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -120,9 +120,13 @@ jobs:
         id: dmf-sha
         shell: pwsh
         run: |
+          # ImageVersion is a runner process env var, not an Actions `env:` context value,
+          # so capture it here for the cache key (invalidates on toolchain image upgrades).
           $sha = git rev-parse HEAD:DMF
+          $imageVersion = $env:ImageVersion
           echo "sha=$sha" >> $env:GITHUB_OUTPUT
-          Write-Output "DMF submodule commit $sha"
+          echo "image-version=$imageVersion" >> $env:GITHUB_OUTPUT
+          Write-Output "DMF submodule commit $sha (ImageVersion=$imageVersion)"
 
       - name: 'Cache DMF libraries'
         if: matrix.platform != 'x86'
@@ -130,7 +134,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: DMF/Release/${{ matrix.platform }}
-          key: dmf-v1-${{ matrix.platform }}-${{ steps.dmf-sha.outputs.sha }}-${{ env.ImageVersion }}
+          key: dmf-v1-${{ matrix.platform }}-${{ steps.dmf-sha.outputs.sha }}-${{ steps.dmf-sha.outputs.image-version }}
 
       - name: 'Build'
         shell: cmd