bpo-33125: Add support for building and releasing Windows ARM64 packages (GH-16828)

Note that the support is not actually enabled yet, and so we won't be publishing these packages. However, for those who want to build it themselves (even by reusing the Azure Pipelines definition), it's now relatively easy to enable.

29 files changed, 286 insertions, 74 deletions

diff --git a/.azure-pipelines/ci.yml b/.azure-pipelines/ci.yml
index fe10e45b67..4c2f115cd9 100644
--- a/.azure-pipelines/ci.yml
+++ b/.azure-pipelines/ci.yml
@@ -145,7 +145,7 @@ jobs:
         buildOpt: '-p x64'
         testRunTitle: '$(Build.SourceBranchName)-win64'
         testRunPlatform: win64
-    maxParallel: 2
+    maxParallel: 4
 
   steps:
   - template: ./windows-steps.yml
diff --git a/.azure-pipelines/pr.yml b/.azure-pipelines/pr.yml
index 09209fc0c9..73d4f55b86 100644
--- a/.azure-pipelines/pr.yml
+++ b/.azure-pipelines/pr.yml
@@ -145,7 +145,10 @@ jobs:
         buildOpt: '-p x64'
         testRunTitle: '$(System.PullRequest.TargetBranch)-win64'
         testRunPlatform: win64
-    maxParallel: 2
+      winarm64:
+        arch: arm64
+        buildOpt: '-p arm64'
+    maxParallel: 4
 
   steps:
   - template: ./windows-steps.yml
diff --git a/.azure-pipelines/windows-release/build-steps.yml b/.azure-pipelines/windows-release/build-steps.yml
index d4563cd0d7..e2b6683f46 100644
--- a/.azure-pipelines/windows-release/build-steps.yml
+++ b/.azure-pipelines/windows-release/build-steps.yml
@@ -43,7 +43,7 @@ steps:
 
 - powershell: |
     $env:SigningCertificate = $null
-    .\python.bat PC\layout -vv -t "$(Build.BinariesDirectory)\catalog" --catalog "${env:CAT}.cdf" --preset-default
+    python PC\layout -vv -b "$(Build.BinariesDirectory)\bin" -t "$(Build.BinariesDirectory)\catalog" --catalog "${env:CAT}.cdf" --preset-default --arch $(Arch)
     makecat "${env:CAT}.cdf"
     del "${env:CAT}.cdf"
     if (-not (Test-Path "${env:CAT}.cat")) {
@@ -52,6 +52,7 @@ steps:
   displayName: 'Generate catalog'
   env:
     CAT: $(Build.BinariesDirectory)\bin\$(Arch)\python
+    PYTHON_HEXVERSION: $(VersionHex)
 
 - task: PublishPipelineArtifact@0
   displayName: 'Publish binaries'
diff --git a/.azure-pipelines/windows-release/layout-command.yml b/.azure-pipelines/windows-release/layout-command.yml
index 2dcd6ed26c..406ccd859f 100644
--- a/.azure-pipelines/windows-release/layout-command.yml
+++ b/.azure-pipelines/windows-release/layout-command.yml
@@ -1,12 +1,20 @@
 steps:
+- task: DownloadPipelineArtifact@1
+  displayName: 'Download artifact: bin_$(HostArch)'
+  condition: and(succeeded(), variables['HostArch'])
+  inputs:
+    artifactName: bin_$(HostArch)
+    targetPath: $(Build.BinariesDirectory)\bin_$(HostArch)
+
 - powershell: >
     Write-Host (
     '##vso[task.setvariable variable=LayoutCmd]&
-    "{0}\bin\python.exe"
+    "$(Python)"
     "{1}\PC\layout"
     -vv
     --source "{1}"
     --build "{0}\bin"
+    --arch "$(Name)"
     --temp "{0}\layout-temp"
     --include-cat "{0}\bin\python.cat"
     --doc-build "{0}\doc"'
diff --git a/.azure-pipelines/windows-release/msi-steps.yml b/.azure-pipelines/windows-release/msi-steps.yml
index f7bff162f8..a460eb1bac 100644
--- a/.azure-pipelines/windows-release/msi-steps.yml
+++ b/.azure-pipelines/windows-release/msi-steps.yml
@@ -54,6 +54,7 @@ steps:
   - powershell: |
       copy $(Build.BinariesDirectory)\amd64\Activate.ps1 Lib\venv\scripts\common\Activate.ps1 -Force
     displayName: 'Copy signed files into sources'
+    condition: and(succeeded(), variables['SigningCertificate'])
 
   - script: |
       call Tools\msi\get_externals.bat
diff --git a/.azure-pipelines/windows-release/stage-build.yml b/.azure-pipelines/windows-release/stage-build.yml
index c98576ef97..60d72b282d 100644
--- a/.azure-pipelines/windows-release/stage-build.yml
+++ b/.azure-pipelines/windows-release/stage-build.yml
@@ -16,14 +16,16 @@ jobs:
     env:
       BUILDDIR: $(Build.BinariesDirectory)\Doc
 
-  #- powershell: iwr "https://www.python.org/ftp/python/3.7.3/python373.chm" -OutFile "$(Build.BinariesDirectory)\python390a0.chm"
-  #  displayName: 'Cheat at building CHM docs'
-
   - script: Doc\make.bat htmlhelp
     displayName: 'Build CHM docs'
     env:
       BUILDDIR: $(Build.BinariesDirectory)\Doc
 
+  #- powershell: |
+  #    mkdir -Force "$(Build.BinariesDirectory)\Doc\htmlhelp"
+  #    iwr "https://www.python.org/ftp/python/3.8.0/python380.chm" -OutFile "$(Build.BinariesDirectory)\Doc\htmlhelp\python390a0.chm"
+  #  displayName: 'Cheat at building CHM docs'
+
   - task: CopyFiles@2
     displayName: 'Assemble artifact: Doc'
     inputs:
@@ -65,6 +67,16 @@ jobs:
         Arch: amd64
         Platform: x64
         Configuration: Debug
+      arm64:
+        Name: arm64
+        Arch: arm64
+        Platform: ARM64
+        Configuration: Release
+      arm64_d:
+        Name: arm64_d
+        Arch: arm64
+        Platform: ARM64
+        Configuration: Debug
 
   steps:
     - template: ./build-steps.yml
diff --git a/.azure-pipelines/windows-release/stage-layout-embed.yml b/.azure-pipelines/windows-release/stage-layout-embed.yml
index 09857ff676..3306e1cbc4 100644
--- a/.azure-pipelines/windows-release/stage-layout-embed.yml
+++ b/.azure-pipelines/windows-release/stage-layout-embed.yml
@@ -19,6 +19,11 @@ jobs:
         Name: amd64
         Python: $(Build.BinariesDirectory)\bin\python.exe
         PYTHONHOME: $(Build.SourcesDirectory)
+      arm64:
+        Name: arm64
+        HostArch: amd64
+        Python: $(Build.BinariesDirectory)\bin_amd64\python.exe
+        PYTHONHOME: $(Build.SourcesDirectory)
 
   steps:
   - template: ./checkout.yml
diff --git a/.azure-pipelines/windows-release/stage-layout-full.yml b/.azure-pipelines/windows-release/stage-layout-full.yml
index 12c3472390..78bc1b3975 100644
--- a/.azure-pipelines/windows-release/stage-layout-full.yml
+++ b/.azure-pipelines/windows-release/stage-layout-full.yml
@@ -13,11 +13,18 @@ jobs:
     matrix:
       win32:
         Name: win32
-        Python: $(Build.BinariesDirectory)\bin_$(Name)\python.exe
+        Python: $(Build.BinariesDirectory)\bin\python.exe
         PYTHONHOME: $(Build.SourcesDirectory)
+        TclLibrary: $(Build.BinariesDirectory)\tcltk_lib\tcl8
       amd64:
         Name: amd64
-        Python: $(Build.BinariesDirectory)\bin_$(Name)\python.exe
+        Python: $(Build.BinariesDirectory)\bin\python.exe
+        PYTHONHOME: $(Build.SourcesDirectory)
+        TclLibrary: $(Build.BinariesDirectory)\tcltk_lib\tcl8
+      arm64:
+        Name: arm64
+        HostArch: amd64
+        Python: $(Build.BinariesDirectory)\bin_amd64\python.exe
         PYTHONHOME: $(Build.SourcesDirectory)
 
   steps:
@@ -43,13 +50,15 @@ jobs:
 
   - task: DownloadPipelineArtifact@1
     displayName: 'Download artifact: tcltk_lib_$(Name)'
+    condition: and(succeeded(), variables['TclLibrary'])
     inputs:
       artifactName: tcltk_lib_$(Name)
       targetPath: $(Build.BinariesDirectory)\tcltk_lib
 
   - powershell: |
-      copy $(Build.BinariesDirectory)\bin\Activate.ps1 Lib\venv\scripts\common\Activate.ps1 -Force
+      copy "$(Build.BinariesDirectory)\bin\Activate.ps1" Lib\venv\scripts\common\Activate.ps1 -Force
     displayName: 'Copy signed files into sources'
+    condition: and(succeeded(), variables['SigningCertificate'])
 
   - template: ./layout-command.yml
 
@@ -57,7 +66,7 @@ jobs:
       $(LayoutCmd) --copy "$(Build.ArtifactStagingDirectory)\layout" --preset-default
     displayName: 'Generate full layout'
     env:
-      TCL_LIBRARY: $(Build.BinariesDirectory)\tcltk_lib\tcl8
+      TCL_LIBRARY: $(TclLibrary)
 
   - task: PublishPipelineArtifact@0
     displayName: 'Publish Artifact: layout_full_$(Name)'
diff --git a/.azure-pipelines/windows-release/stage-layout-msix.yml b/.azure-pipelines/windows-release/stage-layout-msix.yml
index ba86392f3e..60a5c9ea54 100644
--- a/.azure-pipelines/windows-release/stage-layout-msix.yml
+++ b/.azure-pipelines/windows-release/stage-layout-msix.yml
@@ -12,11 +12,18 @@ jobs:
     matrix:
       #win32:
       #  Name: win32
-      #  Python: $(Build.BinariesDirectory)\bin_$(Name)\python.exe
+      #  Python: $(Build.BinariesDirectory)\bin\python.exe
       #  PYTHONHOME: $(Build.SourcesDirectory)
+      #  TclLibrary: $(Build.BinariesDirectory)\tcltk_lib\tcl8
       amd64:
         Name: amd64
-        Python: $(Build.BinariesDirectory)\bin_$(Name)\python.exe
+        Python: $(Build.BinariesDirectory)\bin\python.exe
+        PYTHONHOME: $(Build.SourcesDirectory)
+        TclLibrary: $(Build.BinariesDirectory)\tcltk_lib\tcl8
+      arm64:
+        Name: arm64
+        HostArch: amd64
+        Python: $(Build.BinariesDirectory)\bin_amd64\python.exe
         PYTHONHOME: $(Build.SourcesDirectory)
 
   steps:
@@ -36,13 +43,15 @@ jobs:
 
   - task: DownloadPipelineArtifact@1
     displayName: 'Download artifact: tcltk_lib_$(Name)'
+    condition: and(succeeded(), variables['TclLibrary'])
     inputs:
       artifactName: tcltk_lib_$(Name)
       targetPath: $(Build.BinariesDirectory)\tcltk_lib
 
   - powershell: |
-      copy $(Build.BinariesDirectory)\bin\Activate.ps1 Lib\venv\scripts\common\Activate.ps1 -Force
+      copy "$(Build.BinariesDirectory)\bin\Activate.ps1" Lib\venv\scripts\common\Activate.ps1 -Force
     displayName: 'Copy signed files into sources'
+    condition: and(succeeded(), variables['SigningCertificate'])
 
   - template: ./layout-command.yml
 
@@ -51,7 +60,7 @@ jobs:
       $(LayoutCmd) --copy "$(Build.ArtifactStagingDirectory)\appx-store" --preset-appx --precompile
     displayName: 'Generate store APPX layout'
     env:
-      TCL_LIBRARY: $(Build.BinariesDirectory)\tcltk_lib\tcl8
+      TCL_LIBRARY: $(TclLibrary)
 
   - task: PublishPipelineArtifact@0
     displayName: 'Publish Artifact: layout_appxstore_$(Name)'
@@ -79,7 +88,7 @@ jobs:
       $(LayoutCmd) --copy "$(Build.ArtifactStagingDirectory)\appx" --preset-appx --precompile --include-symbols --include-tests
     displayName: 'Generate sideloading APPX layout'
     env:
-      TCL_LIBRARY: $(Build.BinariesDirectory)\tcltk_lib\tcl8
+      TCL_LIBRARY: $(TclLibrary)
 
   - task: PublishPipelineArtifact@0
     displayName: 'Publish Artifact: layout_appx_$(Name)'
diff --git a/.azure-pipelines/windows-release/stage-layout-nuget.yml b/.azure-pipelines/windows-release/stage-layout-nuget.yml
index 7954c4547f..7e20f89530 100644
--- a/.azure-pipelines/windows-release/stage-layout-nuget.yml
+++ b/.azure-pipelines/windows-release/stage-layout-nuget.yml
@@ -13,11 +13,16 @@ jobs:
     matrix:
       win32:
         Name: win32
-        Python: $(Build.BinariesDirectory)\bin_$(Name)\python.exe
+        Python: $(Build.BinariesDirectory)\bin\python.exe
         PYTHONHOME: $(Build.SourcesDirectory)
       amd64:
         Name: amd64
-        Python: $(Build.BinariesDirectory)\bin_$(Name)\python.exe
+        Python: $(Build.BinariesDirectory)\bin\python.exe
+        PYTHONHOME: $(Build.SourcesDirectory)
+      arm64:
+        Name: arm64
+        HostArch: amd64
+        Python: $(Build.BinariesDirectory)\bin_amd64\python.exe
         PYTHONHOME: $(Build.SourcesDirectory)
 
   steps:
@@ -32,14 +37,13 @@ jobs:
   - powershell: |
       copy $(Build.BinariesDirectory)\bin\Activate.ps1 Lib\venv\scripts\common\Activate.ps1 -Force
     displayName: 'Copy signed files into sources'
+    condition: and(succeeded(), variables['SigningCertificate'])
 
   - template: ./layout-command.yml
 
   - powershell: |
       $(LayoutCmd) --copy "$(Build.ArtifactStagingDirectory)\nuget" --preset-nuget
     displayName: 'Generate nuget layout'
-    env:
-      TCL_LIBRARY: $(Build.BinariesDirectory)\bin_$(Name)\tcl\tcl8
 
   - task: PublishPipelineArtifact@0
     displayName: 'Publish Artifact: layout_nuget_$(Name)'
diff --git a/.azure-pipelines/windows-release/stage-pack-msix.yml b/.azure-pipelines/windows-release/stage-pack-msix.yml
index eebc63fb88..f17ba9628e 100644
--- a/.azure-pipelines/windows-release/stage-pack-msix.yml
+++ b/.azure-pipelines/windows-release/stage-pack-msix.yml
@@ -20,6 +20,16 @@ jobs:
         Artifact: appxstore
         Suffix: -store
         Upload: true
+      arm64:
+        Name: arm64
+        Artifact: appx
+        Suffix:
+        ShouldSign: true
+      arm64_store:
+        Name: arm64
+        Artifact: appxstore
+        Suffix: -store
+        Upload: true
 
   steps:
   - template: ./checkout.yml
diff --git a/.azure-pipelines/windows-release/stage-pack-nuget.yml b/.azure-pipelines/windows-release/stage-pack-nuget.yml
index f59bbe9b39..34619fc5fd 100644
--- a/.azure-pipelines/windows-release/stage-pack-nuget.yml
+++ b/.azure-pipelines/windows-release/stage-pack-nuget.yml
@@ -15,6 +15,8 @@ jobs:
         Name: amd64
       win32:
         Name: win32
+      arm64:
+        Name: arm64
 
   steps:
   - checkout: none
diff --git a/.azure-pipelines/windows-release/stage-publish-nugetorg.yml b/.azure-pipelines/windows-release/stage-publish-nugetorg.yml
index 570cdb3ec5..5aba048cd7 100644
--- a/.azure-pipelines/windows-release/stage-publish-nugetorg.yml
+++ b/.azure-pipelines/windows-release/stage-publish-nugetorg.yml
@@ -31,6 +31,11 @@ jobs:
       buildVersionToDownload: specific
       buildId: $(BuildToPublish)
 
+  - powershell: gci pythonarm*.nupkg | %{ Write-Host "Not publishing: $($_.Name)"; gi $_ } | del
+    displayName: 'Prevent publishing ARM/ARM64 packages'
+    workingDirectory: '$(Build.BinariesDirectory)\nuget'
+    condition: and(succeeded(), not(variables['PublishArmPackages']))
+
   - task: NuGetCommand@2
     displayName: Push packages
     condition: and(succeeded(), eq(variables['SigningCertificate'], variables['__RealSigningCertificate']))
diff --git a/.azure-pipelines/windows-release/stage-publish-pythonorg.yml b/.azure-pipelines/windows-release/stage-publish-pythonorg.yml
index 2dd354a8c2..6c61e9ac3b 100644
--- a/.azure-pipelines/windows-release/stage-publish-pythonorg.yml
+++ b/.azure-pipelines/windows-release/stage-publish-pythonorg.yml
@@ -39,6 +39,10 @@ jobs:
       artifactName: embed
       downloadPath: $(Build.BinariesDirectory)
 
+  - powershell: gci *embed-arm*.zip | %{ Write-Host "Not publishing: $($_.Name)"; gi $_ } | del
+    displayName: 'Prevent publishing ARM/ARM64 packages'
+    workingDirectory: '$(Build.BinariesDirectory)\embed'
+    condition: and(succeeded(), not(variables['PublishArmPackages']))
 
   - task: DownloadPipelineArtifact@1
     displayName: 'Download artifact from $(BuildToPublish): Doc'
diff --git a/.azure-pipelines/windows-release/stage-sign.yml b/.azure-pipelines/windows-release/stage-sign.yml
index 2307c6c9c8..a0adc05812 100644
--- a/.azure-pipelines/windows-release/stage-sign.yml
+++ b/.azure-pipelines/windows-release/stage-sign.yml
@@ -19,6 +19,8 @@ jobs:
         Name: win32
       amd64:
         Name: amd64
+      arm64:
+        Name: arm64
 
   steps:
   - template: ./checkout.yml
diff --git a/.azure-pipelines/windows-steps.yml b/.azure-pipelines/windows-steps.yml
index 794a23a5d7..f502c40637 100644
--- a/.azure-pipelines/windows-steps.yml
+++ b/.azure-pipelines/windows-steps.yml
@@ -19,9 +19,11 @@ steps:
 
 - script: python.bat -m test.pythoninfo
   displayName: 'Display build info'
+  condition: and(succeeded(), variables['testRunPlatform'])
 
 - script: PCbuild\rt.bat -q -uall -u-cpu -rwW --slowest --timeout=1200 -j0 --junit-xml="$(Build.BinariesDirectory)\test-results.xml" --tempdir="$(Build.BinariesDirectory)\test"
   displayName: 'Tests'
+  condition: and(succeeded(), variables['testRunPlatform'])
   env:
     PREFIX: $(Py_OutDir)\$(arch)
 
@@ -32,4 +34,4 @@ steps:
     mergeTestResults: true
     testRunTitle: $(testRunTitle)
     platform: $(testRunPlatform)
-  condition: succeededOrFailed()
+  condition: and(succeededOrFailed(), variables['testRunPlatform'])
diff --git a/Misc/NEWS.d/next/Windows/2019-11-14-08-57-50.bpo-33125.EN5MWS.rst b/Misc/NEWS.d/next/Windows/2019-11-14-08-57-50.bpo-33125.EN5MWS.rst
new file mode 100644
index 0000000000..0bc98c1a2f
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2019-11-14-08-57-50.bpo-33125.EN5MWS.rst
@@ -0,0 +1 @@
+Add support for building and releasing Windows ARM64 packages.
diff --git a/PC/layout/main.py b/PC/layout/main.py
index 3ca49d08e8..305cb517d0 100644
--- a/PC/layout/main.py
+++ b/PC/layout/main.py
@@ -285,14 +285,13 @@ def _compile_one_py(src, dest, name, optimize, checked=True):
         log_warning("Failed to compile {}", src)
         return None
 
+
 # name argument added to address bpo-37641
 def _py_temp_compile(src, name, ns, dest_dir=None, checked=True):
     if not ns.precompile or src not in PY_FILES or src.parent in DATA_DIRS:
         return None
     dest = (dest_dir or ns.temp) / (src.stem + ".pyc")
-    return _compile_one_py(
-        src, dest, name, optimize=2, checked=checked
-    )
+    return _compile_one_py(src, dest, name, optimize=2, checked=checked)
 
 
 def _write_to_zip(zf, dest, src, ns, checked=True):
@@ -497,6 +496,13 @@ def main():
         "-b", "--build", metavar="dir", help="Specify the build directory", type=Path
     )
     parser.add_argument(
+        "--arch",
+        metavar="architecture",
+        help="Specify the target architecture",
+        type=str,
+        default=None,
+    )
+    parser.add_argument(
         "--doc-build",
         metavar="dir",
         help="Specify the docs build directory",
@@ -587,6 +593,8 @@ def main():
         ns.doc_build = (Path.cwd() / ns.doc_build).resolve()
     if ns.include_cat and not ns.include_cat.is_absolute():
         ns.include_cat = (Path.cwd() / ns.include_cat).resolve()
+    if not ns.arch:
+        ns.arch = "amd64" if sys.maxsize > 2 ** 32 else "win32"
 
     if ns.copy and not ns.copy.is_absolute():
         ns.copy = (Path.cwd() / ns.copy).resolve()
@@ -602,6 +610,7 @@ def main():
 Source: {ns.source}
 Build:  {ns.build}
 Temp:   {ns.temp}
+Arch:   {ns.arch}
 
 Copy to: {ns.copy}
 Zip to:  {ns.zip}
@@ -609,6 +618,15 @@ Catalog: {ns.catalog}""",
         ns=ns,
     )
 
+    if ns.arch not in ("win32", "amd64", "arm32", "arm64"):
+        log_error("--arch is not a valid value (win32, amd64, arm32, arm64)")
+        return 4
+    if ns.arch in ("arm32", "arm64"):
+        for n in ("include_idle", "include_tcltk"):
+            if getattr(ns, n):
+                log_warning(f"Disabling --{n.replace('_', '-')} on unsupported platform")
+                setattr(ns, n, False)
+
     if ns.include_idle and not ns.include_tcltk:
         log_warning("Assuming --include-tcltk to support --include-idle")
         ns.include_tcltk = True
diff --git a/PC/layout/support/appxmanifest.py b/PC/layout/support/appxmanifest.py
index de5813a253..9e008f793c 100644
--- a/PC/layout/support/appxmanifest.py
+++ b/PC/layout/support/appxmanifest.py
@@ -28,7 +28,14 @@ APPX_DATA = dict(
     ),
     DisplayName="Python {}".format(VER_DOT),
     Description="The Python {} runtime and console.".format(VER_DOT),
-    ProcessorArchitecture="x64" if IS_X64 else "x86",
+)
+
+APPX_PLATFORM_DATA = dict(
+    _keys=("ProcessorArchitecture",),
+    win32=("x86",),
+    amd64=("x64",),
+    arm32=("arm",),
+    arm64=("arm64",),
 )
 
 PYTHON_VE_DATA = dict(
@@ -65,7 +72,7 @@ IDLE_VE_DATA = dict(
     BackgroundColor="transparent",
 )
 
-PY_PNG = '_resources/py.png'
+PY_PNG = "_resources/py.png"
 
 APPXMANIFEST_NS = {
     "": "http://schemas.microsoft.com/appx/manifest/foundation/windows10",
@@ -147,18 +154,22 @@ RESOURCES_XML_TEMPLATE = r"""<?xml version="1.0" encoding="UTF-8" standalone="ye
 
 SCCD_FILENAME = "PC/classicAppCompat.sccd"
 
+SPECIAL_LOOKUP = object()
+
 REGISTRY = {
     "HKCU\\Software\\Python\\PythonCore": {
         VER_DOT: {
             "DisplayName": APPX_DATA["DisplayName"],
             "SupportUrl": "https://www.python.org/",
-            "SysArchitecture": "64bit" if IS_X64 else "32bit",
+            "SysArchitecture": SPECIAL_LOOKUP,
             "SysVersion": VER_DOT,
             "Version": "{}.{}.{}".format(VER_MAJOR, VER_MINOR, VER_MICRO),
             "InstallPath": {
                 "": "[{AppVPackageRoot}]",
                 "ExecutablePath": "[{{AppVPackageRoot}}]\\python{}.exe".format(VER_DOT),
-                "WindowedExecutablePath": "[{{AppVPackageRoot}}]\\pythonw{}.exe".format(VER_DOT),
+                "WindowedExecutablePath": "[{{AppVPackageRoot}}]\\pythonw{}.exe".format(
+                    VER_DOT
+                ),
             },
             "Help": {
                 "Main Python Documentation": {
@@ -338,6 +349,16 @@ def _get_registry_entries(ns, root="", d=None):
                 if len(fullkey.parts) > 1:
                     yield str(fullkey), None, None
             yield from _get_registry_entries(ns, fullkey, value)
+        elif value is SPECIAL_LOOKUP:
+            if key == "SysArchitecture":
+                return {
+                    "win32": "32bit",
+                    "amd64": "64bit",
+                    "arm32": "32bit",
+                    "arm64": "64bit",
+                }[ns.arch]
+            else:
+                raise ValueError(f"Key '{key}' unhandled for special lookup")
         elif len(r.parts) > 1:
             yield str(r), key, value
 
@@ -376,14 +397,18 @@ def get_appxmanifest(ns):
     NS = APPXMANIFEST_NS
     QN = ET.QName
 
+    data = dict(APPX_DATA)
+    for k, v in zip(APPX_PLATFORM_DATA["_keys"], APPX_PLATFORM_DATA[ns.arch]):
+        data[k] = v
+
     node = xml.find("m:Identity", NS)
     for k in node.keys():
-        value = APPX_DATA.get(k)
+        value = data.get(k)
         if value:
             node.set(k, value)
 
     for node in xml.find("m:Properties", NS):
-        value = APPX_DATA.get(node.tag.rpartition("}")[2])
+        value = data.get(node.tag.rpartition("}")[2])
         if value:
             node.text = value
 
@@ -405,7 +430,7 @@ def get_appxmanifest(ns):
         ["python", "python{}".format(VER_MAJOR), "python{}".format(VER_DOT)],
         PYTHON_VE_DATA,
         "console",
-        ("python.file", [".py"], '"%1"', 'Python File', PY_PNG),
+        ("python.file", [".py"], '"%1"', "Python File", PY_PNG),
     )
 
     add_application(
@@ -416,7 +441,7 @@ def get_appxmanifest(ns):
         ["pythonw", "pythonw{}".format(VER_MAJOR), "pythonw{}".format(VER_DOT)],
         PYTHONW_VE_DATA,
         "windows",
-        ("python.windowedfile", [".pyw"], '"%1"', 'Python File (no console)', PY_PNG),
+        ("python.windowedfile", [".pyw"], '"%1"', "Python File (no console)", PY_PNG),
     )
 
     if ns.include_pip and ns.include_launchers:
@@ -428,7 +453,7 @@ def get_appxmanifest(ns):
             ["pip", "pip{}".format(VER_MAJOR), "pip{}".format(VER_DOT)],
             PIP_VE_DATA,
             "console",
-            ("python.wheel", [".whl"], 'install "%1"', 'Python Wheel'),
+            ("python.wheel", [".whl"], 'install "%1"', "Python Wheel"),
         )
 
     if ns.include_idle and ns.include_launchers:
diff --git a/PC/layout/support/constants.py b/PC/layout/support/constants.py
index d76fa3bbf3..a8647631e9 100644
--- a/PC/layout/support/constants.py
+++ b/PC/layout/support/constants.py
@@ -5,15 +5,31 @@ Constants for generating the layout.
 __author__ = "Steve Dower <steve.dower@python.org>"
 __version__ = "3.8"
 
+import os
+import re
 import struct
 import sys
 
-VER_MAJOR, VER_MINOR, VER_MICRO, VER_FIELD4 = struct.pack(">i", sys.hexversion)
+
+def _unpack_hexversion():
+    try:
+        hexversion = int(os.getenv("PYTHON_HEXVERSION"), 16)
+    except (TypeError, ValueError):
+        hexversion = sys.hexversion
+    return struct.pack(">i", sys.hexversion)
+
+
+def _get_suffix(field4):
+    name = {0xA0: "a", 0xB0: "b", 0xC0: "c"}.get(field4 & 0xF0, "")
+    if name:
+        serial = field4 & 0x0F
+        return f"{name}{serial}"
+    return ""
+
+
+VER_MAJOR, VER_MINOR, VER_MICRO, VER_FIELD4 = _unpack_hexversion()
+VER_SUFFIX = _get_suffix(VER_FIELD4)
 VER_FIELD3 = VER_MICRO << 8 | VER_FIELD4
-VER_NAME = {"alpha": "a", "beta": "b", "candidate": "rc"}.get(
-    sys.version_info.releaselevel, ""
-)
-VER_SERIAL = sys.version_info.serial if VER_NAME else ""
 VER_DOT = "{}.{}".format(VER_MAJOR, VER_MINOR)
 
 PYTHON_DLL_NAME = "python{}{}.dll".format(VER_MAJOR, VER_MINOR)
@@ -21,8 +37,6 @@ PYTHON_STABLE_DLL_NAME = "python{}.dll".format(VER_MAJOR)
 PYTHON_ZIP_NAME = "python{}{}.zip".format(VER_MAJOR, VER_MINOR)
 PYTHON_PTH_NAME = "python{}{}._pth".format(VER_MAJOR, VER_MINOR)
 
-PYTHON_CHM_NAME = "python{}{}{}{}{}.chm".format(
-    VER_MAJOR, VER_MINOR, VER_MICRO, VER_NAME, VER_SERIAL
+PYTHON_CHM_NAME = "python{}{}{}{}.chm".format(
+    VER_MAJOR, VER_MINOR, VER_MICRO, VER_SUFFIX
 )
-
-IS_X64 = sys.maxsize > 2 ** 32
diff --git a/PC/layout/support/nuspec.py b/PC/layout/support/nuspec.py
index ba26ff337e..b85095c555 100644
--- a/PC/layout/support/nuspec.py
+++ b/PC/layout/support/nuspec.py
@@ -13,25 +13,21 @@ PYTHON_NUSPEC_NAME = "python.nuspec"
 NUSPEC_DATA = {
     "PYTHON_TAG": VER_DOT,
     "PYTHON_VERSION": os.getenv("PYTHON_NUSPEC_VERSION"),
-    "PYTHON_BITNESS": "64-bit" if IS_X64 else "32-bit",
-    "PACKAGENAME": os.getenv("PYTHON_NUSPEC_PACKAGENAME"),
-    "PACKAGETITLE": os.getenv("PYTHON_NUSPEC_PACKAGETITLE"),
     "FILELIST": r'    <file src="**\*" target="tools" />',
 }
 
-if not NUSPEC_DATA["PYTHON_VERSION"]:
-    if VER_NAME:
-        NUSPEC_DATA["PYTHON_VERSION"] = "{}.{}-{}{}".format(
-            VER_DOT, VER_MICRO, VER_NAME, VER_SERIAL
-        )
-    else:
-        NUSPEC_DATA["PYTHON_VERSION"] = "{}.{}".format(VER_DOT, VER_MICRO)
-
-if not NUSPEC_DATA["PACKAGETITLE"]:
-    NUSPEC_DATA["PACKAGETITLE"] = "Python" if IS_X64 else "Python (32-bit)"
+NUSPEC_PLATFORM_DATA = dict(
+    _keys=("PYTHON_BITNESS", "PACKAGENAME", "PACKAGETITLE"),
+    win32=("32-bit", "pythonx86", "Python (32-bit)"),
+    amd64=("64-bit", "python", "Python"),
+    arm32=("ARM", "pythonarm", "Python (ARM)"),
+    arm64=("ARM64", "pythonarm64", "Python (ARM64)"),
+)
 
-if not NUSPEC_DATA["PACKAGENAME"]:
-    NUSPEC_DATA["PACKAGENAME"] = "python" if IS_X64 else "pythonx86"
+if not NUSPEC_DATA["PYTHON_VERSION"]:
+    NUSPEC_DATA["PYTHON_VERSION"] = "{}.{}{}{}".format(
+        VER_DOT, VER_MICRO, "-" if VER_SUFFIX else "", VER_SUFFIX
+    )
 
 FILELIST_WITH_PROPS = r"""    <file src="**\*" exclude="python.props" target="tools" />
     <file src="python.props" target="build\native" />"""
@@ -56,11 +52,21 @@ NUSPEC_TEMPLATE = r"""<?xml version="1.0"?>
 """
 
 
+def _get_nuspec_data_overrides(ns):
+    for k, v in zip(NUSPEC_PLATFORM_DATA["_keys"], NUSPEC_PLATFORM_DATA[ns.arch]):
+        ev = os.getenv("PYTHON_NUSPEC_" + k)
+        if ev:
+            yield k, ev
+        yield k, v
+
+
 def get_nuspec_layout(ns):
     if ns.include_all or ns.include_nuspec:
-        data = NUSPEC_DATA
+        data = dict(NUSPEC_DATA)
+        for k, v in _get_nuspec_data_overrides(ns):
+            if not data.get(k):
+                data[k] = v
         if ns.include_all or ns.include_props:
-            data = dict(data)
             data["FILELIST"] = FILELIST_WITH_PROPS
         nuspec = NUSPEC_TEMPLATE.format_map(data)
         yield "python.nuspec", ("python.nuspec", nuspec.encode("utf-8"))
diff --git a/PC/layout/support/props.py b/PC/layout/support/props.py
index 4d3b06195f..b1560b5244 100644
--- a/PC/layout/support/props.py
+++ b/PC/layout/support/props.py
@@ -18,15 +18,9 @@ PROPS_DATA = {
 }
 
 if not PROPS_DATA["PYTHON_VERSION"]:
-    if VER_NAME:
-        PROPS_DATA["PYTHON_VERSION"] = "{}.{}-{}{}".format(
-            VER_DOT, VER_MICRO, VER_NAME, VER_SERIAL
-        )
-    else:
-        PROPS_DATA["PYTHON_VERSION"] = "{}.{}".format(VER_DOT, VER_MICRO)
-
-if not PROPS_DATA["PYTHON_PLATFORM"]:
-    PROPS_DATA["PYTHON_PLATFORM"] = "x64" if IS_X64 else "Win32"
+    PROPS_DATA["PYTHON_VERSION"] = "{}.{}{}{}".format(
+        VER_DOT, VER_MICRO, "-" if VER_SUFFIX else "", VER_SUFFIX
+    )
 
 PROPS_DATA["PYTHON_TARGET"] = "_GetPythonRuntimeFilesDependsOn{}{}_{}".format(
     VER_MAJOR, VER_MINOR, PROPS_DATA["PYTHON_PLATFORM"]
@@ -94,5 +88,13 @@ PROPS_TEMPLATE = r"""<?xml version="1.0" encoding="utf-8"?>
 def get_props_layout(ns):
     if ns.include_all or ns.include_props:
         # TODO: Filter contents of props file according to included/excluded items
-        props = PROPS_TEMPLATE.format_map(PROPS_DATA)
+        d = dict(PROPS_DATA)
+        if not d.get("PYTHON_PLATFORM"):
+            d["PYTHON_PLATFORM"] = {
+                "win32": "Win32",
+                "amd64": "X64",
+                "arm32": "ARM",
+                "arm64": "ARM64",
+            }[ns.arch]
+        props = PROPS_TEMPLATE.format_map(d)
         yield "python.props", ("python.props", props.encode("utf-8"))
diff --git a/PCbuild/build.bat b/PCbuild/build.bat
index bce599329e..623409c24e 100644
--- a/PCbuild/build.bat
+++ b/PCbuild/build.bat
@@ -57,7 +57,7 @@ set conf=Release
 set target=Build
 set dir=%~dp0
 set parallel=/m
-set verbose=/nologo /v:m
+set verbose=/nologo /v:m /clp:summary
 set kill=
 set do_pgo=
 set pgo_job=-m test --pgo
diff --git a/PCbuild/find_msbuild.bat b/PCbuild/find_msbuild.bat
index a2810f09c4..bc9d00c22c 100644
--- a/PCbuild/find_msbuild.bat
+++ b/PCbuild/find_msbuild.bat
@@ -32,7 +32,7 @@
 @rem VS 2017 and later provide vswhere.exe, which can be used
 @if not exist "%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" goto :skip_vswhere
 @set _Py_MSBuild_Root=
-@for /F "tokens=*" %%i in ('"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -property installationPath -latest') DO @(set _Py_MSBuild_Root=%%i\MSBuild)
+@for /F "tokens=*" %%i in ('"%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe" -property installationPath -latest -prerelease') DO @(set _Py_MSBuild_Root=%%i\MSBuild)
 @if not defined _Py_MSBuild_Root goto :skip_vswhere
 @for %%j in (Current 15.0) DO @if exist "%_Py_MSBuild_Root%\%%j\Bin\msbuild.exe" (set MSBUILD="%_Py_MSBuild_Root%\%%j\Bin\msbuild.exe")
 @set _Py_MSBuild_Root=
diff --git a/PCbuild/get_externals.bat b/PCbuild/get_externals.bat
index 100149e83c..f6daf325ef 100644
--- a/PCbuild/get_externals.bat
+++ b/PCbuild/get_externals.bat
@@ -52,7 +52,7 @@ echo.Fetching external libraries...
 
 set libraries=
 set libraries=%libraries%                                       bzip2-1.0.6
-if NOT "%IncludeLibffiSrc%"=="false" set libraries=%libraries%  libffi-3.3.0-rc0-r1
+if NOT "%IncludeLibffiSrc%"=="false" set libraries=%libraries%  libffi
 if NOT "%IncludeSSLSrc%"=="false" set libraries=%libraries%     openssl-1.1.1d
 set libraries=%libraries%                                       sqlite-3.28.0.0
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tcl-core-8.6.9.0
diff --git a/PCbuild/pcbuild.proj b/PCbuild/pcbuild.proj
index 35f173ff86..22a9eed18d 100644
--- a/PCbuild/pcbuild.proj
+++ b/PCbuild/pcbuild.proj
@@ -60,7 +60,7 @@
     <!-- _ssl will build _socket as well, which may cause conflicts in parallel builds -->
     <ExtensionModules Include="_socket" Condition="!$(IncludeSSL) or !$(IncludeExternals)" />
     <ExternalModules Include="_ssl;_hashlib" Condition="$(IncludeSSL)" />
-    <ExternalModules Include="_tkinter" Condition="$(IncludeTkinter)" />
+    <ExternalModules Include="_tkinter" Condition="$(IncludeTkinter) and $(Platform) != 'ARM' and $(Platform) != 'ARM64'" />
     <ExtensionModules Include="@(ExternalModules->'%(Identity)')" Condition="$(IncludeExternals)" />
     <Projects Include="@(ExtensionModules->'%(Identity).vcxproj')" Condition="$(IncludeExtensions)" />
     <!-- Test modules -->
diff --git a/PCbuild/prepare_libffi.bat b/PCbuild/prepare_libffi.bat
index c65a5f7010..f41ba83379 100644
--- a/PCbuild/prepare_libffi.bat
+++ b/PCbuild/prepare_libffi.bat
@@ -93,7 +93,10 @@ echo LIBFFI_SOURCE: %LIBFFI_SOURCE%
 echo MSVCC        : %MSVCC%
 echo.
 
-if not exist Makefile.in (%SH% -lc "(cd $LIBFFI_SOURCE; ./autogen.sh;)")
+if not exist Makefile.in (
+    %SH% -lc "(cd $LIBFFI_SOURCE; ./autogen.sh;)"
+    if errorlevel 1 exit /B 1
+)
 
 if "%BUILD_X64%"=="1" call :BuildOne x64 x86_64-w64-cygwin x86_64-w64-cygwin
 if "%BUILD_X86%"=="1" call :BuildOne x86 i686-pc-cygwin i686-pc-cygwin
@@ -158,11 +161,13 @@ echo ================================================================
 echo Configure the build to generate fficonfig.h and ffi.h
 echo ================================================================
 %SH% -lc "(cd $OLDPWD; ./configure CC='%MSVCC% %ASSEMBLER% %BUILD_PDB%' CXX='%MSVCC% %ASSEMBLER% %BUILD_PDB%' LD='link' CPP='cl -nologo -EP' CXXCPP='cl -nologo -EP' CPPFLAGS='-DFFI_BUILDING_DLL' %BUILD_NOOPT% NM='dumpbin -symbols' STRIP=':' --build=$BUILD --host=$HOST;)"
+if errorlevel 1 exit /B %ERRORLEVEL%
 
 echo ================================================================
 echo Building libffi
 echo ================================================================
 %SH% -lc "(cd $OLDPWD; export PATH=/usr/bin:$PATH; cp src/%SRC_ARCHITECTURE%/ffitarget.h include; make; find .;)"
+if errorlevel 1 exit /B %ERRORLEVEL%
 
 REM Tests are not needed to produce artifacts
 if "%LIBFFI_TEST%" EQU "1" (
diff --git a/PCbuild/python_uwp.vcxproj b/PCbuild/python_uwp.vcxproj
index 14e138cbed..5ff120a0da 100644
--- a/PCbuild/python_uwp.vcxproj
+++ b/PCbuild/python_uwp.vcxproj
@@ -1,6 +1,14 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|ARM">
+      <Configuration>Debug</Configuration>
+      <Platform>ARM</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|ARM64">
+      <Configuration>Debug</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
     <ProjectConfiguration Include="Debug|Win32">
       <Configuration>Debug</Configuration>
       <Platform>Win32</Platform>
@@ -9,6 +17,14 @@
       <Configuration>Debug</Configuration>
       <Platform>x64</Platform>
     </ProjectConfiguration>
+    <ProjectConfiguration Include="PGInstrument|ARM">
+      <Configuration>PGInstrument</Configuration>
+      <Platform>ARM</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGInstrument|ARM64">
+      <Configuration>PGInstrument</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
     <ProjectConfiguration Include="PGInstrument|Win32">
       <Configuration>PGInstrument</Configuration>
       <Platform>Win32</Platform>
@@ -17,6 +33,14 @@
       <Configuration>PGInstrument</Configuration>
       <Platform>x64</Platform>
     </ProjectConfiguration>
+    <ProjectConfiguration Include="PGUpdate|ARM">
+      <Configuration>PGUpdate</Configuration>
+      <Platform>ARM</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGUpdate|ARM64">
+      <Configuration>PGUpdate</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
     <ProjectConfiguration Include="PGUpdate|Win32">
       <Configuration>PGUpdate</Configuration>
       <Platform>Win32</Platform>
@@ -25,6 +49,14 @@
       <Configuration>PGUpdate</Configuration>
       <Platform>x64</Platform>
     </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|ARM">
+      <Configuration>Release</Configuration>
+      <Platform>ARM</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|ARM64">
+      <Configuration>Release</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
     <ProjectConfiguration Include="Release|Win32">
       <Configuration>Release</Configuration>
       <Platform>Win32</Platform>
diff --git a/PCbuild/pythonw_uwp.vcxproj b/PCbuild/pythonw_uwp.vcxproj
index e2c0171049..828d0d1cca 100644
--- a/PCbuild/pythonw_uwp.vcxproj
+++ b/PCbuild/pythonw_uwp.vcxproj
@@ -1,6 +1,14 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|ARM">
+      <Configuration>Debug</Configuration>
+      <Platform>ARM</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Debug|ARM64">
+      <Configuration>Debug</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
     <ProjectConfiguration Include="Debug|Win32">
       <Configuration>Debug</Configuration>
       <Platform>Win32</Platform>
@@ -9,6 +17,14 @@
       <Configuration>Debug</Configuration>
       <Platform>x64</Platform>
     </ProjectConfiguration>
+    <ProjectConfiguration Include="PGInstrument|ARM">
+      <Configuration>PGInstrument</Configuration>
+      <Platform>ARM</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGInstrument|ARM64">
+      <Configuration>PGInstrument</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
     <ProjectConfiguration Include="PGInstrument|Win32">
       <Configuration>PGInstrument</Configuration>
       <Platform>Win32</Platform>
@@ -17,6 +33,14 @@
       <Configuration>PGInstrument</Configuration>
       <Platform>x64</Platform>
     </ProjectConfiguration>
+    <ProjectConfiguration Include="PGUpdate|ARM">
+      <Configuration>PGUpdate</Configuration>
+      <Platform>ARM</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="PGUpdate|ARM64">
+      <Configuration>PGUpdate</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
     <ProjectConfiguration Include="PGUpdate|Win32">
       <Configuration>PGUpdate</Configuration>
       <Platform>Win32</Platform>
@@ -25,6 +49,14 @@
       <Configuration>PGUpdate</Configuration>
       <Platform>x64</Platform>
     </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|ARM">
+      <Configuration>Release</Configuration>
+      <Platform>ARM</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|ARM64">
+      <Configuration>Release</Configuration>
+      <Platform>ARM64</Platform>
+    </ProjectConfiguration>
     <ProjectConfiguration Include="Release|Win32">
       <Configuration>Release</Configuration>
       <Platform>Win32</Platform>