How can ı enable cdc_acm driver?

hi,

uname -a

Linux colibri-imx6 3.14.28-dirty #1 SMP Thu Apr 21 11:44:37 EEST 2016 armv7l GNU/Linux

lsmod

Module                  Size  Used by
usb_f_rndis            11423  2
u_ether                 8980  1 usb_f_rndis
usb_f_acm               4105  2
u_serial                8307  1 usb_f_acm
libcomposite           27288  12 usb_f_acm,usb_f_rndis
configfs               20433  4 usb_f_acm,usb_f_rndis,libcomposite



ls /dev | grep -i "GS"

ttyGS0


ls /lib/modules/

3.14.28-dirty

this commands outputs same with yours.

but ı combine telit gprs modem and toradex board via usb cable.

ı did this operation with my ubuntu pc this is work perfectly and ı connect ttyACM0 than commuınicate with gprs modem . but ı want to make this operation on toradex board. we must activate ttyACMx

I take an error again when I installed colibri default images or my dirty images …

    root@colibri-imx6:~# modprobe g_serial
    modprobe: ERROR: could not insert 'g_serial': No such device

this is my colibri_imx6_defconfig file

I just change the config file on my kernel with this steps