how to compile acx module on RT kernel?

I have 2 kernels: and I have an acx111 wireless pci card, which works fine with the default kernel. After installing my real-time kernel, I tried to compile the acx module that my card needs with the real-time kernel, to no avail:

make -C /usr/src/linux- M=/lib/modules/

make: Entering directory /usr/src/linux-' make: *** No targets specified and no makefile found. Stop. make: Leaving directory /usr/src/linux-’

I believe it’s because i’m missing compiling stuff under the real-time kernel:

ls /usr/src/linux-

Module.symvers makedumpfile.config

For comparison purposes, here’s what I have under the default kernel:

ls /usr/src/linux-obj/x86_64/default/

.config Module.symvers include makedumpfile.config scripts
Makefile arch include2 modules.alias