[Galaxy Tab 4 Android Development] retiredtab:
PLEASE BEFORE YOU decide to try this rom, you MUST read all of post 1, 2, 3 and 4 (about 10 minute read). If you think this is an unreasonable request, then stop reading now and find another rom. Thank you.

This is ONLY for the SM-T530NU/SM-T530. I do not have and will NOT build the LTE variants or the millet devices. Any questions asking to build these will be ignored.

I am not responsible for lost data, identity theft, lost money, security vulnerabilities, bricked devices or any other hardware or software malfunctions that comes as a result of flashing this rom.

BACKUP YOUR DATA AND OLD rom BEFORE trying my rom.

If you are NOT an expert in using fastboot, adb, odin, heimdall, twrp, DO NOT use this rom. You must know how to use these tools to revert back to your old rom. If you are new to flashing custom roms, do NOT attempt this. If you need your tablet for work and something important, do NOT flash this rom. This rom could result in a bricked device ,boot loop, complete loss of data or non booting device or you not being able to revert back to your old rom.

What works

1. wifi - note: 5 GHz WiFi networks between channels 149 and 161 are not available on this device

2. brightness

3. external audio

4. GPS

5. audio through headphone jack

6. selinux enforcing

7. DRM level 3 (SD definition)

8. overclocking of CPU/Soc from 1.2Ghz to 1.6Ghz and GPU from 450Mhz to 550Mhz

9. bluetooth

10. audio over bluetooth

Known issues/What doesn't work/what's not tested

NOTE: If any following features are important to you, don't use this rom as I will not be fixing them because I

i. don't use/need that feature

ii. already tried fixing it and couldn't succeed and won't spend anymore time on it.

1. Stock camera front selfie/preview doesn't work at all (reason i and ii). Use opencamera version 1.52 from

https://f-droid.org/en/packages/net.sourceforge.opencamera/

2. gapps (reason i). Some of you require gapps for whatever reason. I use Aurora Store for my purposes and thus have NO KNOWLEDGE of the current state of gapps.

There are various gapps projects (at least 5 in 2023). Each has pros and cons. It's your job to do the research and find a suitable gapps project. I suggest you allocate at least a couple of hours/days doing your own research. My rom works by itself fine without gapps. DO NOT talk about gapps in this thread.

If you need to talk about gapps, I have opened a new thread for your benefit at

https://xdaforums.com/t/msm8226-which-gapps-to-use-discussion-for-20-roms-sm-t530nu.4667033/

Please talk about gapps in that thread, NOT HERE.

3. full disk encryption has been deprecated in Android 13 (LineageOS 20). Our kernel is version 3.4.113 and is too old to support file based encryption (FBE) which is the only encryption supported in Android 13. FBE requires kernel 3.18 or higher and upgrading the kernel is NOT a trivial task and I won't even try for reasons i and ii.

4. offline charging does not work. If you power off the device and then plug in a charger, the device will automatically start the OS and not stay off. I have no plans to fix this for reasons i and ii.

5. Deep sleep or suspend mode. Normally, after the screen goes off, the device goes into deep sleep or suspend mode after 10 seconds. For some reason, the 20 build takes about 1 hour or more before it goes into deep sleep the first time. During this 1 hour or so, the CPU will run at 300Mhz. After it's woken, then the next time it will take about 10 seconds to go into deep sleep. This is based on my testing without any gapps and magisk. Gapps and magisk may or may not affect this.

6. If you want to disable the taskbar and the 3 soft button navigation, you MUST disable the 3 soft button navigation first via settings, system gestures, system navigation, then disable the taskbar via settings, system, buttons. If you do it in reverse order, the device will become very laggy and unresponsive and you have to reboot to get rid of it. Once rebooted, it will work fine.

7. Boot up times. When you boot the device, it will show the Samsung screen logo for about 35 seconds. Then the LineageOS boot animation will take about another 35 seconds (if you have no gapps). There's nothing that can be done to speed up the boot times. This is an almost 10 year old device with entry level specifications so keep that in mind when you are trying/using this rom.

8. Memory leak with Chromium based browsers. If you run a Chromium based browser like Chrome, Brave, Microsoft Edge, etc and open, close, open, close the browser app, there will be a memory leak of 30MB to 50MB each time. You can see this using adb below.

# open up a terminal/command prompt on your PC
adb root
adb shell
ps -A | grep -i zygote
# example output
$ adb root ; adb shell ps -A | grep -i zygote
adbd is already running as root
root 304 1 1733448 97000 poll_schedule_timeout b1fcd238 S zygote
webview_zygote 745 304 1749936 50592 poll_schedule_timeout b1fcd238 S webview_zygote
u0_a121 2499 304 1758944 49768 __skb_recv_datagram b1fccc10 S com.brave.browser_zygote
u0_a121 3405 304 1758944 49756 __skb_recv_datagram b1fccc10 S com.brave.browser_zygote

Over a period of a few days, this memory leak causes free memory to decrease and can lead to slower performance.

If you have root, you can kill these processes or simply reboot the OS to reclaim the memory. Firefox based browsers do NOT have this problem. In addition, the built in Webview engine does NOT have this problem. I use DuckDuckGo + Webview engine and there is NO memory leak.

9. If you're on stock rom, you MUST BE on Android 5.x. If you're on Android 4.x, upgrade to 5.x FIRST, then you can use this rom.

Source Code

The kernel source code is at

https://github.com/retiredtab/android_kernel_samsung_msm8226/tree/20

All the device, vendor, kernel trees and build instructions are in FAQ #1, post 2.

Thanks

1. LineageOS-UL team for integrating patches into the LineageOS repos.

2. @matteo0026 for building and maintaining 16.0, 17.1 and 18.1

3. LineageOS team for source code