Question

I am attempting to embed a Mono library and MonoTouch into an iPhone application. I had everything working and then something happened on my machine (MonoTouch update?) and now I am unable to link the application when targeting the device. Everything builds fine for the simulator, but I get over a thousand warnings and some errors when targeting the device. The Mono libraries that it is trying to link against are the wrong architecture.

ld: warning: ARM function mono_aot_version not 4-byte aligned
ld: warning: ARM function mono_aot_full_aot not 4-byte aligned
ld: warning: ARM function mono_runtime_version not 4-byte aligned
ld: warning: ARM function mono_aot_assembly_name not 4-byte aligned
ld: warning: ARM function name_0 not 4-byte aligned
ld: warning: ARM function name_1 not 4-byte aligned
ld: warning: ARM function name_2 not 4-byte aligned
...
... lots of these warnings
...
ld: warning: ARM function name_53 not 4-byte aligned
ld: warning: ARM function name_54 not 4-byte aligned
ld: warning: ARM function name_55 not 4-byte aligned
ld: warning: ARM function name_56 not 4-byte aligned
ld: warning: ignoring file /Developer/MonoTouch/SDKs/MonoTouch.iphoneos.sdk/usr/lib/libmono.a, file was built for archive which is not the architecture being linked (armv7)
ld: warning: ignoring file /Developer/MonoTouch/SDKs/MonoTouch.iphoneos.sdk/usr/lib/libmonotouch.a, file was built for archive which is not the architecture being linked (armv7)
Undefined symbols for architecture armv7:
  "_monotouch_setup_classmap", referenced from:
      _monotouch_create_classes in registrar.o
  "_mono_object_new", referenced from:
      -[CalcEvaluator init] in CalcEvaluator.o
  "_mono_aot_register_module", referenced from:
      -[CalcEvaluator init] in CalcEvaluator.o
  "_mono_jit_init", referenced from:
  -[CalcEvaluator init] in CalcEvaluator.o
  "_mono_runtime_object_init", referenced from:
      -[CalcEvaluator init] in CalcEvaluator.o
  "_mono_assembly_get_image", referenced from:
      -[CalcEvaluator init] in CalcEvaluator.o
  "_mono_assembly_open", referenced from:
      -[CalcEvaluator init] in CalcEvaluator.o
  "_mono_jit_set_aot_only", referenced from:
      -[CalcEvaluator init] in CalcEvaluator.o
  "_mono_class_from_name", referenced from:
      -[CalcEvaluator init] in CalcEvaluator.o
ld: symbol(s) not found for architecture armv7
collect2: ld returned 1 exit status

My guess is that it has something to do with MonoTouch not being activated. I’ve tried re-installing MonoTouch and re-activating MonoTouch. Neither had any affect on errors.

Other Linker Flags

-ObjC -L/Developer/MonoTouch/SDKs/MonoTouch.$(PLATFORM_NAME).sdk/usr/lib -lmono -lmonotouch -all_load

Mono Version

$ mono -V
Mono JIT compiler version 2.6.7 (tarball Tue Aug 24 16:33:27 MDT 2010)
Copyright (C) 2002-2010 Novell, Inc and Contributors. www.mono-project.com
TLS:           normal
GC:            Included Boehm (with typed GC)
SIGSEGV:       normal
Notification:  Thread + polling
Architecture:  x86
Disabled:      none

MonoTouch Version

$ /Developer/MonoTouch/usr/bin/mtouch --version
mtouch 3.2.6.9797

I can take this same project and build it on another machine and it builds as expected. Any help in tracking this down is much appreciated.

Answer 1

The 4.3 SDK does not allow linking an armv6 library into an armv7 app. Either change your application to target armv6 only, or upgrade to MonoTouch 4.