There are only a few steps, following the README.SUSE in the kernel-source package:
- install the kernel-syms and kernel-source packages
- copy the kernel sources to some other place where you have write access as a normal user (this is not in the README, but I hate doing stuff like that as root, so I'm doing it anyway)
- patch the source
- build the module
Or, as an almost-copy'n'pasteable list of commands:
cd /tmp
cp -a /usr/src/linux/ . # do not only copy the symlink ;)
cd linux/drivers/gpu/drm/i915/
patch < /tmp/i915-nofbc.diff # your diff
make -C /usr/src/linux-obj/x86_64/desktop M=$(pwd)
ls -l i915.ko
You need to adjust the directory given to "make -C" to your desired kernel flavour, of course, but that's it. Copy the module over to /lib/modules and reboot (I usually save the old module somewhere else, in case something goes wrong, but you probably figured that out already).