Work around a kernel bug on Android.

runtime/vm/signal_handler.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_SIGNAL_HANDLER_H_
 #define VM_SIGNAL_HANDLER_H_
 
 #include "vm/allocation.h"
 #include "vm/globals.h"
 
@@ skipping 25 matching lines @@
 };
 #endif
 
 namespace dart {
 
 typedef void (*SignalAction)(int signal, siginfo_t* info,
                              void* context);
 
 class SignalHandler : public AllStatic {
  public:
+  // Note: older linux kernels on ARM might require a trampoline to
+  // work around incorrect Thumb -> ARM transitions. See SignalHandlerTrampoline
+  // in thread_interrupter_android.cc for more details.
   static void Install(SignalAction action);
   static void Remove();
   static uintptr_t GetProgramCounter(const mcontext_t& mcontext);
   static uintptr_t GetFramePointer(const mcontext_t& mcontext);
   static uintptr_t GetCStackPointer(const mcontext_t& mcontext);
   static uintptr_t GetDartStackPointer(const mcontext_t& mcontext);
   static uintptr_t GetLinkRegister(const mcontext_t& mcontext);
  private:
 };
 
 
 }  // namespace dart
 
 #endif  // VM_SIGNAL_HANDLER_H_