Using HHVM 3.7.1 and GDLib extension, and you try to load a font,
you may encounter the following error:
Fatal error: f_imageloadfont is not supported: NYI in image.php on line 2
This is because the function
imageloadfont(); is not implemented yet.
Here is the Github issue you can read about an update: https://github.com/facebook/hhvm/issues/5468