ci(buildv2): add build/QEMU/Linux jobs for Build system v2

Add the parallel set of CI jobs that exercise the cmakev2 path end-to-end
via the IDF_BUILD_V2 shim. All jobs are gated on the `buildv2` MR label
with `allow_failure: true` so unrelated MRs do not pay for the extra
build matrix.

- `.gitlab/ci/build.yml`: add the buildv2 child build pipeline that
  re-runs the full app build matrix with IDF_BUILD_V2=y, plus the
  Windows buildv2 build job. The generator script injects IDF_BUILD_V2
  and a PIPELINE_COMMIT_SHA suffix into each child job and broadens
  target_test job filters so v1 and buildv2 artifacts upload to distinct
  s3 cache paths and each child pipeline tests its own binary.
- `.gitlab/ci/host-test.yml`: add the QEMU (esp32, esp32c3) and Linux
  pytest buildv2 jobs.
- `.idf_build_apps.toml`: parameterize build_dir with BUILDV2_DIR_SUFFIX
  (set to _v2 only on the buildv2 pipeline).

.gitlab/ci/build.yml

@@ -128,6 +128,77 @@ build_child_pipeline:
         job: generate_build_child_pipeline
     strategy: depend
 
+# Generates a separate child-pipeline YAML for the cmakev2 build system.
+# The build_dir stays identical to cmakev1 (build_<target>_<config>); v1/v2
+# binaries are kept separate in s3 by suffixing PIPELINE_COMMIT_SHA — see
+# the python injection below — which idf-ci uses unmodified in its s3
+# prefix (project/<sha>/...). Keeping build_dir identical preserves the
+# upstream pytest matching that uses app.build_path to filter test cases.
+generate_build_child_pipeline_buildv2:
+  extends:
+    - .build_template
+    - .rules:labels:buildv2
+  tags: [fast_run, shiny]
+  variables:
+    # The build child pipeline's app list is fixed here, at generation time.
+    # Set IDF_BUILD_V2 so that manifest `disable: if IDF_BUILD_V2 == "1"` rules
+    # take effect during app discovery; otherwise those apps (e.g. kasan_test,
+    # IDF-15864) are discovered, built and target-tested even though the build
+    # jobs run with IDF_BUILD_V2 injected by patch_buildv2_child_pipeline.py.
+    IDF_BUILD_V2: "1"
+  dependencies: # set dependencies to null to avoid missing artifacts issue
+  needs:
+    - pipeline_variables
+    - job: pre_check_complete
+      artifacts: false
+    - job: baseline_manifest_sha
+      optional: true
+  artifacts:
+    paths:
+      - buildv2_child_pipeline.yml
+      - test_related_apps.txt
+      - non_test_related_apps.txt
+    expire_in: 1 week
+    when: always
+  script:
+    - idf-ci --debug gitlab build-child-pipeline
+      -p components
+      -p examples
+      -p tools/test_apps
+      --modified-files "$MR_MODIFIED_FILES"
+      buildv2_child_pipeline.yml > idfci_buildv2_gen.log 2>&1
+    - tail -20 idfci_buildv2_gen.log
+    - shuf test_related_apps.txt -o test_related_apps.txt
+    - shuf non_test_related_apps.txt -o non_test_related_apps.txt
+    # Patch the generated yaml to activate the cmakev2 shim and route v2 build
+    # and target_test artifacts to a distinct s3 namespace. See the script
+    # docstring for the rationale.
+    - python tools/ci/dynamic_pipelines/scripts/patch_buildv2_child_pipeline.py buildv2_child_pipeline.yml
+    - 'echo "=== buildv2_child_pipeline.yml (post-injection) ==="; cat buildv2_child_pipeline.yml; echo "=== end ==="'
+
+build_child_pipeline_buildv2:
+  stage: build
+  extends:
+    - .rules:labels:buildv2
+  needs:
+    - job: fast_build_check
+      optional: true
+      artifacts: false
+    - pipeline_variables
+    - generate_build_child_pipeline_buildv2
+  variables:
+    MR_MODIFIED_COMPONENTS: $MR_MODIFIED_COMPONENTS
+    MR_MODIFIED_FILES: $MR_MODIFIED_FILES
+    PARENT_PIPELINE_ID: $CI_PIPELINE_ID
+  inherit:
+    variables: false
+  trigger:
+    include:
+      - artifact: buildv2_child_pipeline.yml
+        job: generate_build_child_pipeline_buildv2
+    strategy: depend
+  allow_failure: true
+
 generate_prebuild_report:
   extends:
     - .build_template

.gitlab/ci/host-test.yml

@@ -353,7 +353,7 @@ build_docker:
 ############################
 # Host test with test apps #
 ############################
-test_pytest_qemu:
+.test_pytest_qemu_template:
   extends:
     - .host_test_template
   artifacts:
@@ -363,15 +363,6 @@ test_pytest_qemu:
       - "**/build*/*.bin"
     reports:
       junit: XUNIT_RESULT.xml
-  parallel:
-    matrix:
-      - IDF_TARGET: "esp32"
-        INSTALL_EXTRA_TOOLS: "qemu-xtensa"
-        # Skip Clang + Xtensa tests due to bootloader size issue
-        IDF_TOOLCHAIN: [gcc]
-      - IDF_TARGET: "esp32c3"
-        INSTALL_EXTRA_TOOLS: "qemu-riscv32"
-        IDF_TOOLCHAIN: [gcc, clang]
   script:
     - run_cmd idf-ci build run
       --build-system cmake
@@ -386,7 +377,20 @@ test_pytest_qemu:
       --ignore-result-files ${KNOWN_FAILURE_CASES_FILE_NAME}
       --qemu-extra-args \"-global driver=timer.$IDF_TARGET.timg,property=wdt_disable,value=true\"
 
-test_pytest_linux:
+test_pytest_qemu:
+  extends:
+    - .test_pytest_qemu_template
+  parallel:
+    matrix:
+      - IDF_TARGET: "esp32"
+        INSTALL_EXTRA_TOOLS: "qemu-xtensa"
+        # Skip Clang + Xtensa tests due to bootloader size issue
+        IDF_TOOLCHAIN: [gcc]
+      - IDF_TARGET: "esp32c3"
+        INSTALL_EXTRA_TOOLS: "qemu-riscv32"
+        IDF_TOOLCHAIN: [gcc, clang]
+
+.test_pytest_linux_template:
   extends:
     - .host_test_template
   artifacts:
@@ -410,6 +414,10 @@ test_pytest_linux:
       --junitxml=XUNIT_RESULT.xml
       --ignore-result-files ${KNOWN_FAILURE_CASES_FILE_NAME}
 
+test_pytest_linux:
+  extends:
+    - .test_pytest_linux_template
+
 test_pytest_macos:
   extends:
     - .host_test_template
@@ -516,6 +524,34 @@ pytest_buildv2_system:
       --junitxml ${CI_PROJECT_DIR}/XUNIT_RESULT.xml
       --ignore-result-files ${KNOWN_FAILURE_CASES_FILE_NAME}
 
+# Run QEMU tests with the cmakev2 build system (via the IDF_BUILD_V2 shim).
+# Triggered only when the 'buildv2' MR label is set.
+test_pytest_qemu_buildv2:
+  extends:
+    - .test_pytest_qemu_template
+    - .rules:labels:buildv2
+  allow_failure: true
+  parallel:
+    matrix:
+      - IDF_TARGET: "esp32"
+        INSTALL_EXTRA_TOOLS: "qemu-xtensa"
+        IDF_TOOLCHAIN: [gcc]
+      - IDF_TARGET: "esp32c3"
+        INSTALL_EXTRA_TOOLS: "qemu-riscv32"
+        IDF_TOOLCHAIN: [gcc]
+  variables:
+    IDF_BUILD_V2: "1"
+
+# Run Linux-target pytest tests with the cmakev2 build system (via the
+# IDF_BUILD_V2 shim). Triggered only when the 'buildv2' MR label is set.
+test_pytest_linux_buildv2:
+  extends:
+    - .test_pytest_linux_template
+    - .rules:labels:buildv2
+  allow_failure: true
+  variables:
+    IDF_BUILD_V2: "1"
+
 pytest_build_system_macos:
   extends:
     - .test_build_system_template