[swarming] Use armv7l for most 32-bit ARM on NetBSD

For the purposes of the Go netbsd-arm builder, we need to be able
to distinguish ARMv6 from later (v7+) architectures. Only ARMv7 has
the synchronization instructions that allow Go binaries to run on
multi-core machines.

This special-cases the 'netbsd' OS type to return armv7l for 32-bit
ARMv7 machines.

I have not added FreeBSD and OpenBSD support since their values for
machine and processor are a bit different.

Part of golang/go#63698

Change-Id: I798c7ec459b453ebfbc6bf2912f1bd06b8919325
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/5943105
Reviewed-by: Vadim Shtayura <[email protected]>
Commit-Queue: Benny Siegert <[email protected]>

appengine/swarming/swarming_bot/api/os_utilities.py

@@ -249,6 +249,17 @@ def get_cpu_type():
     # platform.machine() returns the aix machine ID (uname -m), which is
     # not useful. Modern AIX only supports powerpc64.
     return 'ppc64'
+  elif sys.platform.startswith('netbsd') and platform.machine() == 'evbarm':
+    # NetBSD has multiple ARM sub-platforms.
+    processor = platform.processor().lower()
+    if processor == 'aarch64':
+      return 'arm64'
+    # The following are not quite accurate, since there are also big-endian
+    # variants. E.g. earmv7hfeb is ARMv7, hardware FPU, big-endian.
+    if processor.startswith('earmv6'):
+      return 'armv6l'
+    if processor.startswith('earmv'):
+      return 'armv7l'
   machine = platform.machine().lower()
   if machine in ('amd64', 'x86_64', 'i386', 'i686', 'i86pc'):
     return 'x86'
@@ -317,6 +328,8 @@ def get_cipd_architecture():
   if cpu_type == 'x86':
     return 'amd64' if get_cpu_bitness() == '64' else '386'
   if cpu_type.startswith('armv') and cpu_type.endswith('l'):
+    if get_cipd_os() == 'netbsd':
+      return cpu_type
     # 32-bit ARM: Standardize on ARM v6 baseline.
     return 'armv6l'
   if cpu_type == 'evbarm':  # NetBSD's name for ARM, both 32 and 64-bit

appengine/swarming/swarming_bot/api/os_utilities_test.py

@@ -81,6 +81,19 @@ def test_get_cipd_architecture(self):
       self.mock(os_utilities, 'get_cpu_bitness', lambda: bitness)
       self.assertEqual(os_utilities.get_cipd_architecture(), expected)
 
+  def test_get_cipd_architecture_netbsd(self):
+    cases = [
+        ('amd64', 'x86_64', 'amd64'),
+        ('evbarm', 'aarch64', 'arm64'),
+        ('evbarm', 'earmv6hf', 'armv6l'),
+        ('evbarm', 'earmv7hf', 'armv7l'),
+    ]
+    for machine, processor, expected in cases:
+      self.mock(sys, 'platform', 'netbsd10')
+      self.mock(platform, 'machine', lambda: machine)
+      self.mock(platform, 'processor', lambda: processor)
+      self.assertEqual(os_utilities.get_cipd_architecture(), expected)
+
   def test_get_os_values(self):
     cases = [
         ('openbsd7', '7.2', ['openbsd', 'openbsd-7', 'openbsd-7.2']),