ho una semplice pagina con il segunte codice

Codice PHP:
session_start(); 
se la provo in locale cioè su localhost mi da questi errori

Warning: Cannot send session cookie - headers already sent by (output started at d:\sito\login.php:7) in d:\sito\login.php on line 8

Warning: Cannot send session cache limiter - headers already sent (output started at d:\sito\login.php:7) in d:\sito\login.php on line 8

Warning: open(/tmp\sess_51de3617e522952dd35eebd0592f265c, O_RDWR) failed: No such file or directory (2) in d:\sito\login.php on line 8

Warning: open(/tmp\sess_51de3617e522952dd35eebd0592f265c, O_RDWR) failed: No such file or directory (2) in Unknown on line 0

Warning: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/tmp) in Unknown on line 0


se la provo sul serve no? devo modificare qualcosa per farlo in locale?