Galaxy S5 G900T Custom Rom with ARUnchained.
You should probably do some research on the forums on flashing a custom kernel. There's lots of info out there and I wouldn't recommend wading into those waters until you thoroughly acquaint yourself with the risks and benefits of making such modifications. In brief though you generally flash a kernel with a similar method you use to flashing a custom rom. Like I said be careful though. If you flash the wrong kernel for your device you might end up with a paperweight composed of equal parts plastic glass and aluminum.
With regards to this whole selinux permissive issue: I have been emailing back and forth with the developer of appradio unchained reloaded and he told me he is trying to design a work-around for the selinux permissive requirement. It sounds like it's still in the early stages but we can hope.
Thanks for getting back to me. I did some research as you suggested and I have some update on this. I wanted to share with everyone here who might be trying to do the same thing like me.
I was able to Disable the KNOX and set SE to permissive. I used Omega v11 Custom for this. Omega v11 does the both requirements we are looking for. It Disables KNOX and set SE to Permissive. But first I flashed a recovery using "Philz Touch". Then from the recovery i installed the Omega Zip file. Everything went smoothly and i was ready to connect my phone to the appradio 3.
First I download the ARUnchained Reloded App from google play. Then connected my phone to the Samsung Adapter which is also connected to the Pioneer CD-AH200 cables going back of my AppRadio 3 (DA210) HDMI port. When you connect your phone to the adapter 2(two) apps will become visible. APPs and Pandora button. When I run the app ARUnchained it takes me to the home screen where you will find START, STOP and HOME button. Before i pressed the START on ARU, i went to my HU( Head Unit) and clicked on the APP option. It showed me a Message telling me to make sure i am connected to the Bluetooth and I have appradio App installed by Pioneer. I clicked on Ignore since my HU was connected to the bluetooth already. I didnt install Appradio App since i don't need that. Then it showed me an warning sign telling me not to watch video while driving and put my car on Park. So I have a bypass installed which allows me not to do all those crazy stuff. After switching the bypass on another message screen comes off and i simply clicked on OK.
Now i was mirroring my phone on the HU. I went to ARUnchained app and clicked on Start and nothing happens. Top left side of the phone on notification panel shows letter "R" with "x" sign on top of it. I believe it means HU couldn't connect to the ARU. Also its showing "Listening for Connection" on the screen. I tried moving the screen on HU but it gives me that hand with X sign.
Question is What am i doing wrong? And why is it not working? I went to ARU diagnostics and almost all the options are checked except "Installed as system app" and "Can switch mock locations". Do you think these two options has to be checked as well? If you have ARU, what does it show for you under setting > Diagnostics ? Please let me know.
I made a video on youtube showing whatever i just mentioned here. That might help you to understand better what is happening with my configuration.
Please help me out here and i promise if i can make this work, i will do a step by step HOW TO youtube video on this matter and i am pretty sure we all want to see solve this issue as well.
Video : Since i cannot share video here, look for a video with title "AppRadio ARUnchained Issue" by RockOnRay.