X-Git-Url: https://glassweightruler.freedombox.rocks/gitweb/waydroid.git/blobdiff_plain/80555aba69dd568aa989edea8480487e87d80aac..d8c700bbb8b7bd992b9fe9b43de8a2f3d8e8587f:/tools/helpers/arch.py

diff --git a/tools/helpers/arch.py b/tools/helpers/arch.py
index 35e8516..8f4543a 100644
--- a/tools/helpers/arch.py
+++ b/tools/helpers/arch.py
@@ -1,6 +1,22 @@
 # Copyright 2021 Oliver Smith
 # SPDX-License-Identifier: GPL-3.0-or-later
 import platform
+import logging
+import ctypes
+
+def is_32bit_capable():
+    # man 2 personality
+    personality = ctypes.CDLL(None).personality
+    personality.restype = ctypes.c_int
+    personality.argtypes = [ctypes.c_ulong]
+    # linux/include/uapi/linux/personality.h
+    PER_LINUX32 = 0x0008
+    # mirror e.g. https://github.com/util-linux/util-linux/blob/v2.41/sys-utils/lscpu-cputype.c#L745-L756
+    pers = personality(PER_LINUX32)
+    if pers != -1: # success, revert back to previous persona (typically just PER_LINUX, 0x0000)
+        personality(pers)
+        return True
+    return False # unable to "impersonate" 32-bit host, nothing done
 
 def host():
     machine = platform.machine()
@@ -13,6 +29,23 @@ def host():
         "armv8l": "arm"
     }
     if machine in mapping:
-        return mapping[machine]
+        return maybe_remap(mapping[machine])
     raise ValueError("platform.machine '" + machine + "'"
                      " architecture is not supported")
+
+def maybe_remap(target):
+    if target.startswith("x86"):
+        with open("/proc/cpuinfo") as f:
+            cpuinfo = f.read()
+        if "ssse3" not in cpuinfo:
+            raise ValueError("x86/x86_64 CPU must support SSSE3!")
+        if target == "x86_64" and "sse4_2" not in cpuinfo:
+            logging.info("x86_64 CPU does not support SSE4.2, falling back to x86...")
+            return "x86"
+    elif target == "arm64" and platform.architecture()[0] == "32bit":
+        return "arm"
+    elif target == "arm64" and not is_32bit_capable():
+        logging.info("AArch64 CPU does not appear to support AArch32, assuming arm64_only...")
+        return "arm64_only"
+
+    return target