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Merge topic 'correct_transfer_to_opengl_test'

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c1c43d19 Force GCC linker to see that we need pthread to work around nvidia driver bug.

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !365
This commit is contained in:
Robert Maynard 2016-03-18 10:44:54 -04:00 committed by Kitware Robot
commit 229a416b56
1 changed files with 58 additions and 0 deletions
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58
vtkm/opengl/testing/TestingWindow.h
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@ -22,6 +22,58 @@
#include <vtkm/internal/ExportMacros.h>
#include <vtkm/opengl/testing/WindowBase.h>
#if defined(VTKM_GCC) && defined(VTKM_POSIX) && !defined(__APPLE__)
//
// 1. Some Linux distributions default linker implicitly enables the as-needed
// linking flag. This means that your shared library or executable will only
// link to libraries from which they use symbols. So if you explicitly link to
// pthread but don't use any symbols you wont have a 'DT_NEEDED' entry for
// pthread.
//
// 2. NVidia libGL (driver version 352 ) uses pthread but doesn't have
// a DT_NEEDED entry for the library. When you run ldd or readelf on the library
// you won't detect any reference to the pthread library. Aside this is odd
// since the mesa version does explicitly link to pthread. But if you run the
// following command:
// "strings /usr/lib/nvidia-352/libGL.so.1 | grep pthread | less"
// You will see the following:
// { pthread_create
// pthread_self
// pthread_equal
// pthread_key_crea
// ...
// libpthread.so.0
// libpthread.so
// pthread_create
// }
//
// This is very strong evidence that this library is using pthread.
//
//
// 3. So what does this all mean?
//
// It means that on system that use the linking flag 'as-needed', are using
// the nvidia driver, and don't use pthread will generate binaries that crash
// on launch. The only way to work around this issue is to do either:
//
//
// A: Specify 'no-as-needed' to the linker potentially causing over-linking
// and a slow down in link time
//
// B: Use a method from pthread, making the linker realize that pthread is
// needed.
//
//
// So that is the explanation on why we have the following function which is
// never used and seems very crazy.
#include <pthread.h>
#define VTKM_NVIDIA_PTHREAD_WORKAROUND 1
int vtkm_force_linking_to_pthread_to_fix_nvidia_libgl_bug()
{ return static_cast<int>(pthread_self()); }
#endif
namespace vtkm{
namespace opengl{
namespace testing{
@ -34,6 +86,12 @@ namespace testing{
///
class TestingWindow : public vtkm::opengl::testing::WindowBase<TestingWindow>
{
#if defined(VTKM_NVIDIA_PTHREAD_WORKAROUND)
VTKM_CONT_EXPORT int vtkm_force_linking_to_pthread_to_fix_nvidia_libgl_bug()
{ return vtkm_force_linking_to_pthread_to_fix_nvidia_libgl_bug(); }
#endif
public:
VTKM_CONT_EXPORT TestingWindow(){};