Udev
 

if I have only one session configured, can I stop udev from boot ?

Because I test that my laptop block at udev boot, for about 2 min!, then continue to boot.

I'm not sure what you mean by "one session" but if udevstart is blocking for too long (on my system it only takes ±10 secs to start) then you can try having it start in the background (change udevstart to "udevstart &" in whichever startup script it's blocking in (/etc/rc.d/init.d/udev I think). If this doesn't work too well then you could always take over management of device nodes manually provided your setup is fairly static though this isn't as nice as automagic udev.