Switcheroo gone after last update

Switcheroo gone after last update

since the last kernel update for Ubuntu 13.04, the folder
/sys/kernel/debug/vgaswitcheroo/switch is gone on my Laptop (Acer Aspire
3820TG)
Checking the output of grep -i /boot/config-* tells me that my kernel
supports switcheroo however, the file is gone (and yes, I checked that as
root).
Can anybody please give me a hint? I almost checked the whole internet for
an appropriate answer but nobody seems to have the same problem.
Thanks, Edwin