$ vim /etc/hhvm/php.ini
hhvm.mysql.typed_results = false
hhvm.log.level = Verbose
hhvm.log.no_silencer = true
hhvm.log.header = true
hhvm.log.injected_stackTrace = true
hhvm.log.always_log_unhandled_exceptions = true
hhvm.log.runtime_error_reporting_level = 8191
hhvm.log.use_log_file = true