How to Compile a single module or rt kernel

[Selda_bagcan]

I installed the kernels from 

 and flashed them to sd card. Then i copied the modified .ko files from image that i built for latest non-rt kernel using the compile.sh. My orange pi zero is running rt version. When i try to modprobe the modified and copied module it gives me error:

modprobe: ERROR: could not insert 'libcomposite': Exec format error

I read that incorrect arch could cause this so i ran the file command. libcomposite.ko: ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), BuildID[sha1]=3a49e12c7809bbbdbdc3c5c5bd0fcd53e77dde44, not stripped

i think module i built is not compatible  with rt kernel i downloaded. I need to rebuild kernel with modified source code(only a few lines and 2 files) with rt patch or i need a way to build that module respecting rt kernel version i downloaded. 
Thanks for your attention

[Selda_bagcan]

 By the way i dont need to build latest kernel with rt patch. Igor's version is more than enoguh. I tried to edit sunxi-common.inc for 4.13.10(4.13.10 couldnt found so i typed 4.13.y) but it didnt work.

scripts/Makefile.build:302: recipe for target 'fs/read_write.o' failed

i didnt even modify read_write.o. I only enabled the rt patch and modified a few lines in usb/gadget/composite.c

[Igor]

10 hours ago, Selda_bagcan said:

By the way i dont need to build latest kernel with rt patch

Those were my experiments for testing purposes only. In general, we don't deal with RT kernels.

The problem is that you have to use exactly 4.14.y at the moment. Older versions might be completely broken for building - patches are adjusted to 4.14.y and not to 4.13.y - and they miss some important part ... well, even this one is still not completely finished nor (labeled) stable. But it is the best what exists for H3 boards.

Simply try adding patches from https://www.kernel.org/pub/linux/kernel/projects/rt/4.14/ to userpatches/kernel/sunxi-next and recompile.

 

User our unmodified build script. And good luck.