OPcache is a Zend extension not a PHP one, and the zend_extension directive takes an absolute
path of the opcache.so shareable image and not relative to the
As OPcache isn't bundled with PHP5.4, I assume that you've build OPcache
with the PECL package, but however you've build it, you must use its
absolute path for then Zend extension loader to find it.