Raise an informative error when running on macOS under Rosetta 2.

Current users only get a cryptic "Illegal instruction" crash.

Context: https://github.com/deepmind/mujoco/issues/611
PiperOrigin-RevId: 491705647
Change-Id: I1285897a36e858300ee3d125957e90754be9a7f7

doc/changelog.rst

@@ -70,6 +70,10 @@ General
 - Sensors of type :ref:`user<sensor-user>` no longer require :at:`objtype` and :at:`objname`. If unspecified, the
   objtype will be :ref:`mjOBJ_UNKNOWN<mjtObj>`. ``user`` sensors :at:`datatype` default is now :at-val:`"real"`.
 - Add support for capsules in URDF import.
+- On macOS, issue an informative error message when run under `Rosetta 2 <https://support.apple.com/en-gb/HT211861>`_
+  translation on an Apple Silicon machine. Pre-built MuJoCo binaries make use of
+  `AVX <https://en.wikipedia.org/wiki/Advanced_Vector_Extensions>`_ instructions on x86-64 machines, which is not
+  supported by Rosetta 2. (Before this version, users only get a cryptic "Illegal instruction" message.)
 
 Simulate
 ^^^^^^^^

python/mujoco/__init__.py

@@ -23,6 +23,18 @@ import subprocess
 _SYSTEM = platform.system()
 if _SYSTEM == 'Windows':
   ctypes.WinDLL(os.path.join(os.path.dirname(__file__), 'mujoco.dll'))
+elif _SYSTEM == 'Darwin':
+  proc_translated = subprocess.run(
+      ['sysctl', '-n', 'sysctl.proc_translated'], capture_output=True).stdout
+  try:
+    is_rosetta = bool(int(proc_translated))
+  except ValueError:
+    is_rosetta = False
+  if is_rosetta and platform.machine() == 'x86_64':
+    raise ImportError(
+        'You are running an x86_64 build of Python on an Apple Silicon '
+        'machine. This is not supported by MuJoCo. Please install and run a '
+        'native, arm64 build of Python.')
 
 from mujoco._callbacks import *
 from mujoco._constants import *

simulate/CMakeLists.txt

@@ -122,7 +122,7 @@ target_include_directories(libsimulate PUBLIC $<TARGET_PROPERTY:glfw,INTERFACE_I
 target_link_options(libsimulate PRIVATE ${MUJOCO_SIMULATE_LINK_OPTIONS})
 
 if(APPLE)
-  target_sources(libsimulate PRIVATE macos_save.mm)
+  target_sources(libsimulate PRIVATE macos_gui.mm)
   target_link_libraries(libsimulate PUBLIC "-framework Cocoa")
 endif()
 

simulate/Makefile.macos

@@ -11,8 +11,8 @@ CXXFLAGS=$(CFLAGS) -std=c++17 -stdlib=libc++
 ALLFLAGS=$(CXXFLAGS) -L$(GLFWROOT)/lib -Wl,-rpath,$(MUJOCOPATH)
 
 all:
-	clang++ $(CXXFLAGS)      -c macos_save.mm
+	clang++ $(CXXFLAGS)      -c macos_gui.mm
 	clang++ $(CXXFLAGS)      -c simulate.cc
 	clang $(CFLAGS) -std=c11 -c uitools.c
-	clang++ $(CXXFLAGS) main.cc macos_save.o simulate.o uitools.o  -framework mujoco -framework Cocoa -lglfw -o simulate
+	clang++ $(CXXFLAGS) main.cc macos_gui.o simulate.o uitools.o  -framework mujoco -framework Cocoa -lglfw -o simulate
 	rm *.o

simulate/macos_gui.mm

@@ -17,7 +17,7 @@
 
 #include <Cocoa/Cocoa.h>
 
-std::string getSavePath(const char* filename) {
+std::string GetSavePath(const char* filename) {
   NSSavePanel* panel = [NSSavePanel savePanel];
   NSURL* userDocumentsDir = [NSFileManager.defaultManager URLsForDirectory:NSDocumentDirectory
                                                           inDomains:NSUserDomainMask].firstObject;
@@ -31,3 +31,14 @@ std::string getSavePath(const char* filename) {
     return "";
   }
 }
+
+#ifdef __AVX__
+void DisplayErrorDialogBox(const char* title, const char* msg) {
+  NSAlert *alert = [[[NSAlert alloc] init] autorelease];
+  [alert setMessageText:[NSString stringWithUTF8String:title]];
+  [alert setInformativeText:[NSString stringWithUTF8String:msg]];
+  [alert setAlertStyle:NSAlertStyleCritical];
+  [alert addButtonWithTitle:@"Exit"];
+  [alert runModal];
+}
+#endif

simulate/main.cc

@@ -437,8 +437,25 @@ void PhysicsThread(mj::Simulate* sim, const char* filename) {
 
 //------------------------------------------ main --------------------------------------------------
 
+// machinery for replacing command line error by a macOS dialog box when running under Rosetta
+#if defined(__APPLE__) && defined(__AVX__)
+extern void DisplayErrorDialogBox(const char* title, const char* msg);
+static const char* rosetta_error_msg = nullptr;
+__attribute__((used, visibility("default"))) extern "C" void _mj_rosettaError(const char* msg) {
+  rosetta_error_msg = msg;
+}
+#endif
+
 // run event loop
 int main(int argc, const char** argv) {
+  // display an error if running on macOS under Rosetta 2
+#if defined(__APPLE__) && defined(__AVX__)
+  if (rosetta_error_msg) {
+    DisplayErrorDialogBox("Rosetta 2 is not supported", rosetta_error_msg);
+    std::exit(1);
+  }
+#endif
+
   // print version, check compatibility
   std::printf("MuJoCo version %s\n", mj_versionString());
   if (mjVERSION_HEADER!=mj_version()) {

simulate/simulate.cc

@@ -40,9 +40,9 @@
 // Since the dialog box logic needs to be written in Objective-C, we separate it into a different
 // source file.
 #ifdef __APPLE__
-std::string getSavePath(const char* filename);
+std::string GetSavePath(const char* filename);
 #else
-static std::string getSavePath(const char* filename) {
+static std::string GetSavePath(const char* filename) {
   return filename;
 }
 #endif
@@ -1077,7 +1077,7 @@ void uiEvent(mjuiState* state) {
       switch (it->itemid) {
       case 0:             // Save xml
         {
-          const std::string path = getSavePath("mjmodel.xml");
+          const std::string path = GetSavePath("mjmodel.xml");
           if (!path.empty() && !mj_saveLastXML(path.c_str(), m, err, 200)) {
             std::printf("Save XML error: %s", err);
           }
@@ -1086,7 +1086,7 @@ void uiEvent(mjuiState* state) {
 
       case 1:             // Save mjb
         {
-          const std::string path = getSavePath("mjmodel.mjb");
+          const std::string path = GetSavePath("mjmodel.mjb");
           if (!path.empty()) {
             mj_saveModel(m, path.c_str(), nullptr, 0);
           }
@@ -1850,7 +1850,7 @@ void Simulate::render() {
     // Unfortunately, if we just yank ".xml"/".mjb" from the filename and append .PNG, the macOS
     // file dialog does not automatically open that location. Thus, we defer to a default
     // "screenshot.png" for now.
-    const std::string path = getSavePath("screenshot.png");
+    const std::string path = GetSavePath("screenshot.png");
     if (!path.empty()) {
       if (lodepng::encode(path, rgb.get(), w, h, LCT_RGB)) {
         mju_error("could not save screenshot");

src/engine/CMakeLists.txt

@@ -27,6 +27,7 @@ set(MUJOCO_ENGINE_SRCS
     engine_core_constraint.h
     engine_core_smooth.c
     engine_core_smooth.h
+    engine_crossplatform.c
     engine_crossplatform.h
     engine_derivative.c
     engine_derivative.h

src/engine/engine_crossplatform.c

@@ -0,0 +1,39 @@
+// Copyright 2022 DeepMind Technologies Limited
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#if defined(__APPLE__) && defined(__AVX__)
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/sysctl.h>
+
+__attribute__((weak, visibility("default"))) void _mj_rosettaError(const char* msg) {
+  fprintf(stderr, "%s\n", msg);
+  __asm__ __volatile__ ("ud2");  // raises SIGILL but leave this function at the top of the stack
+}
+
+__attribute__((constructor(10000), target("no-avx"))) static void _mj_checkRosetta() {
+  int is_translated = 0;
+  {
+    size_t len = sizeof(is_translated);
+    if (sysctlbyname("sysctl.proc_translated", &is_translated, &len, NULL, 0)) {
+      is_translated = 0;
+    }
+  }
+  if (is_translated) {
+    _mj_rosettaError("MuJoCo cannot be run under Rosetta 2 on an Apple Silicon machine.");
+  }
+}
+
+#endif  // defined(__APPLE__) && defined(__AVX__)