[UNOFFICIAL][ROM]BETA LineageOS 18.1 for SM-T715 - January 22, 2023

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metterschling

Senior Member

LineageOS 18.1 UNOFFICIAL for 2015 Samsung Galaxy Tab S2 SM-T715 ONLY​

Model: SM-T715 (LTE) - gts28ltexx - 8" screen, Exynos 5433 SoC, LTE
This is the ONLY model that the ROM will work on.
There is NO ROM for the T710, T810 or T815 in this thread. Questions about T710, T810 or T815 will be completely IGNORED.
For T710 please use the equivalent ROM at its separate XDA forum thread.
For T810 please use the equivalent ROM at
its separate XDA forum thread.

You MUST READ posts 1-3 (about 10 minute read) before deciding to install this ROM. If you think this is an unreasonable request, then stop reading now and find another ROM. Thank you.

DISCLAIMER

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.

All involved in bringing this build to you are working voluntarily on it in very limited spare time, and their other life commitments have much higher priority. Don't expect a prompt, or even any, response to questions and bug reports.

Before attempting to install this ROM

1. Ask yourself: would bricking your device be a disaster for you? If yes, don't try this ROM! It can't be guaranteed stable and reliable enough to depend on for daily use.
2. BACKUP YOUR DATA AND EXISTING ROM. Be prepared for a complete restore if anything goes wrong.
3. RESEARCH adb, fastboot, Odin/heimdall, and TWRP and how to use them, if not already familiar with these.

What works
  1. bluetooth
  2. wifi
  3. GPS
  4. brightness
  5. audio through loudspeaker
  6. audio through headphone jack
  7. audio over bluetooth
  8. SELinux enforcing
  9. DRM level 3 (SD definition)
  10. deep sleep
  11. RIL - mobile data and telephony/SMS/Cell Broadcast - some limitations for telephony audio options apply, see below
  12. vibration and haptic feedback
  13. hardware buttons and lighting

What doesn't work

  1. fingerprint. As retiredtab wrote in post 1891 at
    https://forum.xda-developers.com/t/...t810-t815-t815y.3879302/page-95#post-85533725
    the team will not spend anymore time looking at fingerprint. If you need fingerprint to work, stay with stock Samsung ROM.

  2. DRM level 1 (no HD definition). There's more detail in post 1891 above. I will not be trying to achieve level 1 for HD definition. If you need HD definition for your streaming media, stay with stock Samsung ROM.

  3. If you charge the device while it's powered off and then want to power it on, you MUST wait at least 30 seconds AFTER disconnecting the charger cable before pressing the power button otherwise you might run into strange boot problems such as the touch screen not working. While recent builds solved the touchscreen issue, you still might see excessive battery drain until you perform another reboot.

  4. For telephony audio, currently only the loudspeaker option is working. If you try to use/switch to bluetooth audio during a phone call, the audio stack will go wild and afterwards loudspeaker will stop working too until you perform a reboot.

  5. Possibly other features that I haven't tested or do not use.

Source Code

See FAQ 1 for links in post #2.

Thanks
  1. LineageOS team for the upstream source code.
  2. @retiredtab, @ananjaser1211, @lpedia, @Yogi555 and @CuckooPenguin for spending nearing 1 month fixing the 2 most biggest bugs in 17.1 that plagued users for nearly 10 months: the wifi instability and random reboots. These are discussed in detail at
    https://forum.xda-developers.com/t/...rs-running-any-version-of-android-10.4308193/
    https://forum.xda-developers.com/t/...rs-running-any-version-of-android-10.4308203/
  3. A special shout out to retiredtab for providing the T710 ROM and code here which is the base for this ROM. Also this ROM would not have been possible with all the help and mentoring he provided during the past 6 months of development. Also many thanks to lpedia and bluess57 for their outstanding hints and tips.
  4. All past contributors of the exynos5433 code, especially ananjaser1211 for his major contributions and @ripee for working on prior gts2 builds until end of 2021.
  5. @rINanDO for his lmkd spam fix in 18.1.
  6. Alpha testers: simon-edwards for the many hours testing and helping troubleshooting RIL, SELinux policies and various gapps options; Don K and Sir Thopas for addional RIL model testing.
  7. @bluess57 for his excellent code donations for the gts2 LTE models.
  8. retiredtab and lpedia for providing the blueprint for this forum entry and the FAQ in post #2 and constantly improving it. This work is just a little contribution standing on strong shoulders of previous contributions.
 
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metterschling

Senior Member
Frequently Asked Questions. You MUST READ this before posting any questions. Thank you.

QuestionAnswer
Q1. Can I build this ROM for myself? Where are the source and kernel source files?A1. Yes, you can. The source files are listed below.

Kernel
https://github.com/metterschlg/android_kernel_samsung_universal5433

Device Tree
https://github.com/metterschlg/android_device_samsung_gts2-common-selinux
https://github.com/metterschlg/android_device_samsung_gts28ltexx

Vendor
https://github.com/metterschlg/proprietary_vendor_samsung

In addition, there is a repo diff file for device-specific tweaks needed to work and a roomservice.xml (local manifest file) file so you can build this rom yourself. The other patch required for tcp/ip is at https://github.com/DerpFest-11/pack...mmit/22fd53a977eeaf4e36be7bf6358ecf2c2737fa5e

Build manifest can be found at
https://github.com/metterschlg/local_manifests/blob/lineage-18.1/gts28ltexx.xml
Build environment setup is docmented (as code) at
https://github.com/metterschlg/los-devel-scripts
Q2. Is this ROM suitable as a daily driver?A2. It might be, depending on your requirements. You would need to try it yourself, with your preferred apps, to see if suits your purposes. I've been using it myself since mid April 2022 with no major issues.
Q3. What do I do if my app xyz doesn't work?A3. I can't help diagnose problems with random apps I know nothing about. If the app is critically important to you and it doesn't work on this ROM, go back to a ROM where it did work.
Q4. Why is this ROM laggy and/or buggy?A4. The device will be noticeably slower if you're using any Gapps package. Consider going gapps-free. A lot of apps will work without Google's services, or there exist alternatives that will. Check out F-Droid, Aurora Store, NewPipe, etc.
Q5. What TWRP should I use?A5. I use official TWRP 3.6.1_9. Get it from
https://twrp.me/samsung/samsunggalaxytabs280ltexx2015.html
Q6. Why should I use this ROM?A6. You don't have to! If you don't like it, go back to your old ROM.
Q7. Will you offer monthly updates with security patches?A7. I plan to do so. I will try to update the ROM with the monthly security patches after LineageOS has released them, free time permitting. Each monthly build will be quickly tested to make sure the ROM still works, before it's made available (which might in some cases delay the release).
Q8. I'm a newbie. Can you provide step by step instructions?A8. We simply don't have the time to do this, but there are lots of tutorials, videos, etc online showing how to flash custom ROMs and how to deal with common problems. Newbie questions are also accepted in the XDA General Questions and Answers forum. Having said that, @pflyaz has kindly make a guide in post #37.
Q9. Can I report a bug with respect to the ROM?A9. Yes, but you need to supply the following information. If you don't, I won't look at it.

Provide an adb logcat of the problem, and if possible describe how to reproduce it. Note that I can't help if it involves downloading any app I don't already use that requires payment or creating a userid/password.

To get a logcat, open a terminal window on your PC, connect your device to it via USB, and do this:

Bash:
# clear the logcat first
adb logcat -c
# start logcat trace
adb logcat > problem.txt
# reproduce problem
# wait until problem has occurred,
# then stop trace by hitting ctrl-c then zip the problem.txt file
# before uploading it.
Q10. How long will you build 18.1 for this device?A10. For now, 18.1 will be built for all of 2022. After that, we will make a decision depending on a number of factors.
Q11. Do I need to erase everything and format my data before installing this ROM for the first time?A11. Under most circumstances, yes.

If you're coming from stock Samsung Android, or an earlier version of LineageOS, or a different custom ROM, you MUST 'clean flash': boot to TWRP recovery, wipe system, data, dalvik/art cache, and cache partitions, then Format Data, then install this ROM.

If you don't do this you're likely to run into problems, such as getting stuck at the boot animation for more than 5 minutes.
Q12. What Gapps should I use?A12. Your choice! There are several well-known Gapps packages, such as NikGapps, BiTGapps, OpenGapps, and MindTheGapps. OpenGapps is being removed as per this post. Do your own research as to what is the most reliable gapps option for you.

I recommend installing the SMALLEST version of any of these, preferably with just the minimum Google services needed to access the Play Store and run apps that depend on Google services.

You could also consider Google alternatives, such as Aurora Store, which mirrors the Google Play Store apps but doesn't need any Google services itself. Many Play Store apps do not actually depend on Google services.

If you are going to install any Gapps package, follow the installation instructions given for that particular package.
Q13. I'm having problems with Gapps. Can you tell me why it's not working?A13. I can't answer any questions about Gapps, because I don't use them. Ask your questions on the XDA thread for the Gapps package you're using.
Q14. Why isn't my post answered?A14. There are several possible reasons: the question is answered in the FAQ (in which case it will be ignored completely); or it involves apps or operating systems that I don't use; or it's about Gapps, which I don't use; or I simply have not had time to answer any questions.
Q15. What speed up/optimization tips do you suggest?A15. These steps can make a big difference to performance:
  • Turn off animations. Go to Settings > System > Developer options, scroll down to the Drawing section, and set Window, Transition and Animator scale all to "Animation off".
  • Don't install Gapps unless you depend on something that only Google is providing. Use Aurora Store to get your preferred Play Store apps - they will all be available on Aurora Store. You can choose to access this anonymously or use a Google account.
  • Don't run more than two apps at the same time. You can probably listen to music in the background and use a web browser at the same time.
  • Use a web browser with built-in adblock and privacy features, such as Brave.
  • Use NewPipe to watch your streaming content. It has built in adblock so you don't have to watch forced ads.
  • Look for apps that are open source, ad-free and lightweight.
Q16. Does this ROM support Magisk so I can root my device?A16. Magisk works with this ROM and I'm using it, but that could change with any revision and changes by Google. However I can't help with any related issues. Direct any questions about Magisk to the XDA Magisk forum.
Q17. Will this ROM ever become official?A17. Never. Official maintainers have onerous responsibilities, and I know my device trees, code organization and git commits will NOT meet LineageOS standards. I'm not able or willing to take on the responsibilities and commit the extra time to supporting an official build.
Q18. What is the difference between this ROM and others?A18. This ROM tries to be pure LineageOS with little or no modification. Other ROMs may come with a different UI, different bundled apps, etc.
Q19. Will there be any major 18.1 code modifications in the future?A19. I don't anticipate any major modifications. There may be some slight tweaking to the SEpolicy, small bug fixes and minor code cleanup, but all the hard work - getting the ROM up and running, and fixing all the major bugs - has been done. This doesn't mean the code is perfect or well organized, but I won't be making any major changes.
Q20. Why did you fork the trees?A20. I wanted my own private branch where I could make changes that would only affect my own personal builds.
Q21. Can you build a variant of this device? For example, a S-pen version?A21. I cannot and will not try to build for a variant device if I don't physically have that device. I have to be able to boot and test it myself, and there's no guarantee that I can get those variant features working. So I will NEVER build T710, T810 and T815.
Q22. Does this ROM have any wifi connection issues?A22. This ROM's wifi has been stable on the specified device ever since lpedia and retiredtab determined the root cause of the wifi problems back in July 2021 and re-installed the original S2 network 'blobs' with LOS 17.1.
Q23. Is this ROM secure so I can do financial transactions?A23. Although Android monthly security patches do improve general security, this ROM's outdated kernel and old proprietary vendor blobs/drivers will NEVER get updates of any kind, and could have significant security holes.

In addition, although the ROM is SElinux enforcing, there's a good chance that the rules written (about 800+ lines of code) have some errors.

If the device is rooted, this would further weaken the security.

With this information, it's up to you to make an informed decision about whether you trust this ROM to be secure enough for your financial transactions.
Q24. Okay, I understand the consequences and willing to take the risks outlined, now where can I find the BETA ROM?A24. Downloads are at

https://sourceforge.net/projects/los4sgt/files/los18.1/

Please note that there are two builds for every date. Start with the enforcing build, if you hit issues, flash the permissive boot image to determine if your issue is related to SELinux. If you have Magisk installed, you first need to patch the permissive boot image with the Magisk app before flashing.

If your initial enforcing build install does not have working RIL, you might need to fix SELinux labeling of your EFS partition. To do so, use ADB in root mode. Please note that ADB root needs to be enabled in the developer options of your device. Then use the following commands from a PC connected via ADB:

Bash:
adb root
adb shell
# Check if SELinux relabeling is required, do not modify anything
restorecon -R -v -n /efs
# If you see some "Relabeling..." output, run the real relabeling
restorecon -R -v /efs
 
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metterschling

Senior Member
Release notes

January 22, 2023 Release

  • January 2023 LineageOS & Android security fixes. >4200 files changed.
December 17, 2022 Release
  • December 2022 LineageOS & Android security fixes. >3800 files changed.
November 13, 2022 Release.
  • November 2022 LineageOS & Android security fixes. >4000 files changed.
  • Kernel improvements by Ananjaser
  • Starting with these builds I will only publish the SELinux enforcing ROM. If you encounter issues that might be SELinux-related, please first flash the boot_permissive-<date>.img as boot image and re-try to help me identify if the issue is SELinux-related.

October 22, 2022 Release.
Initial public release. First 18.1 T715 ROM with working RIL, also first 18.1 T715 ROM with SELinux in Enforcing mode. T710/T715 common code based on retiredtab's work for T710 so all his latest changes apply as well.
 
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ripee

Recognized Developer / Recognized Contributor
Aug 25, 2014
3,606
6,637
drive.google.com
@metterschling If you don't mind a couple of comments about your scripts, you need not have created a patch for my script. You could have just forked mine and pushed your changes to it. No need to complicate things for novice builders. Secondly, I'm sure your gts28lte tree can be a source of inspiration for the other 3 variants so as to build a complete set. Thirdly, you may be able to let gts28wifi users flash your builds if you add gts28wifi as a TARGET_DEVICE, to make it easier to cover more users in the meantime. Fourthly, you clone so many repos when it could be cleaner to fork then substitute your forks in the roomservice. This could avoid potential repo syncing errors.
 
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metterschling

Senior Member
@metterschling If you don't mind a couple of comments about your scripts, you need not have created a patch for my script. You could have just forked mine and pushed your changes to it. No need to complicate things for novice builders. Secondly, I'm sure your gts28lte tree can be a source of inspiration for the other 3 variants so as to build a complete set. Thirdly, you may be able to let gts28wifi users flash your builds if you add gts28wifi as a TARGET_DEVICE, to make it easier to cover more users in the meantime. Fourthly, you clone so many repos when it could be cleaner to fork then substitute your forks in the roomservice. This could avoid potential repo syncing errors.
Thank you @ripee. Just to be sure: all you above comments are related to my build environment setup script here, correct?
I agree with regards to the patch, this is how I started and just wanted to document my steps as code. During my next free cycle, I'll be looking at reworking this.
Regarding 2) as mentioned in the opening post my work is already the result of synergies between code trees for the other devices, mainly based on retiredtab's trees, and we keep the common set wherever possible.
So there is no need for 3) as gts28wifi users can directly use the equivalent one linked on the top of post #1.
For 4) I'm open for suggestions which clones you are referring to. As an example, I don't want to fork the entire LineageOS tree just to apply the small NetworkStack patch.
 
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metterschling

Senior Member
Thank you @ripee. Just to be sure: all you above comments are related to my build environment setup script here, correct?
I agree with regards to the patch, this is how I started and just wanted to document my steps as code. During my next free cycle, I'll be looking at reworking this.
Regarding 2) as mentioned in the opening post my work is already the result of synergies between code trees for the other devices, mainly based on retiredtab's trees, and we keep the common set wherever possible.
So there is no need for 3) as gts28wifi users can directly use the equivalent one linked on the top of post #1.
For 4) I'm open for suggestions which clones you are referring to. As an example, I don't want to fork the entire LineageOS tree just to apply the small NetworkStack patch.
@ripee I've pushed a new version of the build environment setup script, following your guidance. Please let me know if there are more areas of improvement, very much appreciated!
 

metterschling

Senior Member
November build lineage-18.1-20221113-UNOFFICIAL-gts28ltexx.zip uploaded. Please see FAQ #24 for the download link.

November 13, 2022 release notes:
  • November 2022 LineageOS & Android security fixes. >4000 files changed.
  • Kernel improvements by Ananjaser
  • Starting with these builds I will only publish the SELinux enforcing ROM. If you encounter issues that might be SELinux-related, please first flash the boot_permissive-<date>.img as boot image and re-try to help me identify if the issue is SELinux-related.
Enjoy!
 

ripee

Recognized Developer / Recognized Contributor
Aug 25, 2014
3,606
6,637
drive.google.com
Thank you @ripee. Just to be sure: all you above comments are related to my build environment setup script here, correct?
I agree with regards to the patch, this is how I started and just wanted to document my steps as code. During my next free cycle, I'll be looking at reworking this.
Regarding 2) as mentioned in the opening post my work is already the result of synergies between code trees for the other devices, mainly based on retiredtab's trees, and we keep the common set wherever possible.
So there is no need for 3) as gts28wifi users can directly use the equivalent one linked on the top of post #1.
For 4) I'm open for suggestions which clones you are referring to. As an example, I don't want to fork the entire LineageOS tree just to apply the small NetworkStack patch.
If gts28wifi users get an error that their device is not gts28ltexx, then yes it would be necessary to add it as a target device in the tree. Lineage uses the networkstack repo from google, which you can tell cuz they track the aosp remote, so in this case we have nothing to fork and substitute. Only a patch of google's own repo would be convenient.
 

retiredtab

Senior Member
Nov 16, 2017
1,370
988
Just to clarify, since there has been discussion about the WiFi version (t713), can this ROM be safely flashed on one?

Also I believe I have a t715Y... Would this t715 ROM work on it?
The T713 and T715 have completely different chipsets. T713 is msm8976 and T715 is exynos5433.

If your T715Y is known as "gts28ltexx" OR "gts28lte" as described in post #1, then you can flash this rom on it. You can download an utility called devcheck by flar2 to verify. Your device name will be shown in the system tab under device.

https://play.google.com/store/apps/details?id=flar2.devcheck

metterschling's code checks for gts28lte,gts28ltexx using this below

https://github.com/metterschlg/andr...s28ltexx/blob/lineage-18.1/BoardConfig.mk#L17
 

metterschling

Senior Member
December build lineage-18.1-20221217-UNOFFICIAL-gts28ltexx.zip uploaded. Please see FAQ #24 for the download link.

December 17, 2022 release notes:
  • December 2022 LineageOS & Android security fixes. >3800 files changed.
If you are coming from a previous version of these builds, you can dirty flash, otherwise please perform a factory reset and format data before installing this ROM.

Enjoy
 

mikelosat

Member
Feb 15, 2012
17
0
Hi friends, after loading from TWRP twrp-3.7.0_9-0-gts28ltexx.img.tar on my SM T710, my tab gets stuck on booting with lineageos graphics. I made the backup with TWRP if I upload the files can I repair the tab as before?
 

metterschling

Senior Member
Hi friends, after loading from TWRP twrp-3.7.0_9-0-gts28ltexx.img.tar on my SM T710, my tab gets stuck on booting with lineageos graphics. I made the backup with TWRP if I upload the files can I repair the tab as before?
If I understand correctly, you picked the gts28ltexx version which is for the SM-T715. If your device is the SM-T710 (gts28wifi) I'd strongly recommend to use the ROM and matching TWRP linked in this thread.
If your device is SM-T715, please see FAQ #5 in post #2 of this thread. I use the downlevel TWRP because newer ones did not work for me.
 
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mikelosat

Member
Feb 15, 2012
17
0
I use a SAMSUNG SM-T715 device just as described:
Model: SM-T715 (LTE) - gts28ltexx - 8" screen, Exynos 5433 SoC, LTE.

To be able to install the ROM I used "TWRP twrp-3.7.0_9-0-gts28ltexx.img.tar"

After several attempts I could neither restore the BACKUP nor start the operating system. I had to do a complete WIPE and at that point lineageos advanced, now I'm having problems, I don't have the gapps I downloaded version 11 for ARM but despite having enough space it gives me an error "70" not enough space. I have no google services and no PLAYSTORE, I am in a critical situation, how can I install the google PlayStore? I can't even add gmail account from settings, it's a disaster.
 

mikelosat

Member
Feb 15, 2012
17
0
If I understand correctly, you picked the gts28ltexx version which is for the SM-T715. If your device is the SM-T710 (gts28wifi) I'd strongly recommend to use the ROM and matching TWRP linked in this thread.
If your device is SM-T715, please see FAQ #5 in post #2 of this thread. I use the downlevel TWRP because newer ones did not work for me.
Finally I come to the conclusion, after fully formatting my SAMSUNG SM T715 the ROM started up, the problem was the wrong recovery, using the version indicated in the guide above everything started up correctly.

Unfortunately this ROM is full of bugs and its use is useless, below I will list all the problems it causes during use:

1. 4g calls don't work, during the call you can't hear anything either incoming or outgoing.

2. Bluetooth only works with music while in call it remains mute.

3. the only way to call is to keep the speakerphone open otherwise the call will be silent.

4. Whatsapp is impossible to use and only allows you to use it in beta.

5. Smart Switch as for whatsapp does not work with custom ROMs

6. Does not sync contacts even though sync has started.

It's really a shame after all these hours to find that you've only wasted so much time.

Maybe I've done something wrong, I don't rule it out, maybe someone will be able to give me some advice.
 
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  • 1
    Using Gapps with this ROM

    It can be done, but there are limited benefits to doing so.

    When I started testing this ROM I discovered that MindTheGapps and BiTGapps always give an error accessing /mnt/system. This is due to them expecting a different installation than that provided by TWRP for this system.

    This can be worked around by first installing LOS and then ticking on the box at the end of the initial boot sequence to allow LOS to install its own Boot Manager. Reboot into recovery (now the LOS recovery) after the first boot completes. Re-format and start again in the LOS recovery.

    The LOS formatter will work properly for these two Gapps to pass their instalation checks. But the GUI is pretty awful after using TWRP and a lot of functionality is missing.

    The LOS recovery will then allow you to re-load LOS and either MindTheGapps or BiTGapps. At least to get past this /mnt/system formatting issue.

    MindTheGapps then crashed frequently in my testing. BitGapps was less troublesome but still slowed the system appreciably.

    Meanwhile, OpenGapps works with TWRP formatting. That is to say that it works as well as OpenGapps works at all - which is barely. During the initial bootstrap after installation as many as 15 force closes were seen. The system was best left alone for an hour to stabilise. Shutdown, then restarted. At this point you can setup your accounts and get started t use the tab.

    From this point in the instalations of apps each Gapps from the PlayStore are varied until you run magisk and spoof the security checks. Some Apps are simply missing unless you spoof a later device ID that matchs the OS installed. Some won't allow installations as the security checks detect knox errors.


    I have now switched to using Aurora-Store installed from F-Droid and my tab lasts for days on a single charge. I only have trouble when it comes to apps which require payments via Google Play Store APIs. Which are few and far between.

    For the vast majority of usage you really don't need to use Gapps. You will get a far longer lasting experience without them. But it took me 7 months of testing this ROM to prove that to myself, so I can understand why you are trying to use them when coming from stock or near stock experiences.
  • 3

    LineageOS 18.1 UNOFFICIAL for 2015 Samsung Galaxy Tab S2 SM-T715 ONLY​

    Model: SM-T715 (LTE) - gts28ltexx - 8" screen, Exynos 5433 SoC, LTE
    This is the ONLY model that the ROM will work on.
    There is NO ROM for the T710, T810 or T815 in this thread. Questions about T710, T810 or T815 will be completely IGNORED.
    For T710 please use the equivalent ROM at its separate XDA forum thread.
    For T810 please use the equivalent ROM at
    its separate XDA forum thread.

    You MUST READ posts 1-3 (about 10 minute read) before deciding to install this ROM. If you think this is an unreasonable request, then stop reading now and find another ROM. Thank you.

    DISCLAIMER

    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.

    All involved in bringing this build to you are working voluntarily on it in very limited spare time, and their other life commitments have much higher priority. Don't expect a prompt, or even any, response to questions and bug reports.

    Before attempting to install this ROM

    1. Ask yourself: would bricking your device be a disaster for you? If yes, don't try this ROM! It can't be guaranteed stable and reliable enough to depend on for daily use.
    2. BACKUP YOUR DATA AND EXISTING ROM. Be prepared for a complete restore if anything goes wrong.
    3. RESEARCH adb, fastboot, Odin/heimdall, and TWRP and how to use them, if not already familiar with these.

    What works
    1. bluetooth
    2. wifi
    3. GPS
    4. brightness
    5. audio through loudspeaker
    6. audio through headphone jack
    7. audio over bluetooth
    8. SELinux enforcing
    9. DRM level 3 (SD definition)
    10. deep sleep
    11. RIL - mobile data and telephony/SMS/Cell Broadcast - some limitations for telephony audio options apply, see below
    12. vibration and haptic feedback
    13. hardware buttons and lighting

    What doesn't work

    1. fingerprint. As retiredtab wrote in post 1891 at
      https://forum.xda-developers.com/t/...t810-t815-t815y.3879302/page-95#post-85533725
      the team will not spend anymore time looking at fingerprint. If you need fingerprint to work, stay with stock Samsung ROM.

    2. DRM level 1 (no HD definition). There's more detail in post 1891 above. I will not be trying to achieve level 1 for HD definition. If you need HD definition for your streaming media, stay with stock Samsung ROM.

    3. If you charge the device while it's powered off and then want to power it on, you MUST wait at least 30 seconds AFTER disconnecting the charger cable before pressing the power button otherwise you might run into strange boot problems such as the touch screen not working. While recent builds solved the touchscreen issue, you still might see excessive battery drain until you perform another reboot.

    4. For telephony audio, currently only the loudspeaker option is working. If you try to use/switch to bluetooth audio during a phone call, the audio stack will go wild and afterwards loudspeaker will stop working too until you perform a reboot.

    5. Possibly other features that I haven't tested or do not use.

    Source Code

    See FAQ 1 for links in post #2.

    Thanks
    1. LineageOS team for the upstream source code.
    2. @retiredtab, @ananjaser1211, @lpedia, @Yogi555 and @CuckooPenguin for spending nearing 1 month fixing the 2 most biggest bugs in 17.1 that plagued users for nearly 10 months: the wifi instability and random reboots. These are discussed in detail at
      https://forum.xda-developers.com/t/...rs-running-any-version-of-android-10.4308193/
      https://forum.xda-developers.com/t/...rs-running-any-version-of-android-10.4308203/
    3. A special shout out to retiredtab for providing the T710 ROM and code here which is the base for this ROM. Also this ROM would not have been possible with all the help and mentoring he provided during the past 6 months of development. Also many thanks to lpedia and bluess57 for their outstanding hints and tips.
    4. All past contributors of the exynos5433 code, especially ananjaser1211 for his major contributions and @ripee for working on prior gts2 builds until end of 2021.
    5. @rINanDO for his lmkd spam fix in 18.1.
    6. Alpha testers: simon-edwards for the many hours testing and helping troubleshooting RIL, SELinux policies and various gapps options; Don K and Sir Thopas for addional RIL model testing.
    7. @bluess57 for his excellent code donations for the gts2 LTE models.
    8. retiredtab and lpedia for providing the blueprint for this forum entry and the FAQ in post #2 and constantly improving it. This work is just a little contribution standing on strong shoulders of previous contributions.
    3
    Release notes

    January 22, 2023 Release

    • January 2023 LineageOS & Android security fixes. >4200 files changed.
    December 17, 2022 Release
    • December 2022 LineageOS & Android security fixes. >3800 files changed.
    November 13, 2022 Release.
    • November 2022 LineageOS & Android security fixes. >4000 files changed.
    • Kernel improvements by Ananjaser
    • Starting with these builds I will only publish the SELinux enforcing ROM. If you encounter issues that might be SELinux-related, please first flash the boot_permissive-<date>.img as boot image and re-try to help me identify if the issue is SELinux-related.

    October 22, 2022 Release.
    Initial public release. First 18.1 T715 ROM with working RIL, also first 18.1 T715 ROM with SELinux in Enforcing mode. T710/T715 common code based on retiredtab's work for T710 so all his latest changes apply as well.
    2
    Frequently Asked Questions. You MUST READ this before posting any questions. Thank you.

    QuestionAnswer
    Q1. Can I build this ROM for myself? Where are the source and kernel source files?A1. Yes, you can. The source files are listed below.

    Kernel
    https://github.com/metterschlg/android_kernel_samsung_universal5433

    Device Tree
    https://github.com/metterschlg/android_device_samsung_gts2-common-selinux
    https://github.com/metterschlg/android_device_samsung_gts28ltexx

    Vendor
    https://github.com/metterschlg/proprietary_vendor_samsung

    In addition, there is a repo diff file for device-specific tweaks needed to work and a roomservice.xml (local manifest file) file so you can build this rom yourself. The other patch required for tcp/ip is at https://github.com/DerpFest-11/pack...mmit/22fd53a977eeaf4e36be7bf6358ecf2c2737fa5e

    Build manifest can be found at
    https://github.com/metterschlg/local_manifests/blob/lineage-18.1/gts28ltexx.xml
    Build environment setup is docmented (as code) at
    https://github.com/metterschlg/los-devel-scripts
    Q2. Is this ROM suitable as a daily driver?A2. It might be, depending on your requirements. You would need to try it yourself, with your preferred apps, to see if suits your purposes. I've been using it myself since mid April 2022 with no major issues.
    Q3. What do I do if my app xyz doesn't work?A3. I can't help diagnose problems with random apps I know nothing about. If the app is critically important to you and it doesn't work on this ROM, go back to a ROM where it did work.
    Q4. Why is this ROM laggy and/or buggy?A4. The device will be noticeably slower if you're using any Gapps package. Consider going gapps-free. A lot of apps will work without Google's services, or there exist alternatives that will. Check out F-Droid, Aurora Store, NewPipe, etc.
    Q5. What TWRP should I use?A5. I use official TWRP 3.6.1_9. Get it from
    https://twrp.me/samsung/samsunggalaxytabs280ltexx2015.html
    Q6. Why should I use this ROM?A6. You don't have to! If you don't like it, go back to your old ROM.
    Q7. Will you offer monthly updates with security patches?A7. I plan to do so. I will try to update the ROM with the monthly security patches after LineageOS has released them, free time permitting. Each monthly build will be quickly tested to make sure the ROM still works, before it's made available (which might in some cases delay the release).
    Q8. I'm a newbie. Can you provide step by step instructions?A8. We simply don't have the time to do this, but there are lots of tutorials, videos, etc online showing how to flash custom ROMs and how to deal with common problems. Newbie questions are also accepted in the XDA General Questions and Answers forum. Having said that, @pflyaz has kindly make a guide in post #37.
    Q9. Can I report a bug with respect to the ROM?A9. Yes, but you need to supply the following information. If you don't, I won't look at it.

    Provide an adb logcat of the problem, and if possible describe how to reproduce it. Note that I can't help if it involves downloading any app I don't already use that requires payment or creating a userid/password.

    To get a logcat, open a terminal window on your PC, connect your device to it via USB, and do this:

    Bash:
    # clear the logcat first
    adb logcat -c
    # start logcat trace
    adb logcat > problem.txt
    # reproduce problem
    # wait until problem has occurred,
    # then stop trace by hitting ctrl-c then zip the problem.txt file
    # before uploading it.
    Q10. How long will you build 18.1 for this device?A10. For now, 18.1 will be built for all of 2022. After that, we will make a decision depending on a number of factors.
    Q11. Do I need to erase everything and format my data before installing this ROM for the first time?A11. Under most circumstances, yes.

    If you're coming from stock Samsung Android, or an earlier version of LineageOS, or a different custom ROM, you MUST 'clean flash': boot to TWRP recovery, wipe system, data, dalvik/art cache, and cache partitions, then Format Data, then install this ROM.

    If you don't do this you're likely to run into problems, such as getting stuck at the boot animation for more than 5 minutes.
    Q12. What Gapps should I use?A12. Your choice! There are several well-known Gapps packages, such as NikGapps, BiTGapps, OpenGapps, and MindTheGapps. OpenGapps is being removed as per this post. Do your own research as to what is the most reliable gapps option for you.

    I recommend installing the SMALLEST version of any of these, preferably with just the minimum Google services needed to access the Play Store and run apps that depend on Google services.

    You could also consider Google alternatives, such as Aurora Store, which mirrors the Google Play Store apps but doesn't need any Google services itself. Many Play Store apps do not actually depend on Google services.

    If you are going to install any Gapps package, follow the installation instructions given for that particular package.
    Q13. I'm having problems with Gapps. Can you tell me why it's not working?A13. I can't answer any questions about Gapps, because I don't use them. Ask your questions on the XDA thread for the Gapps package you're using.
    Q14. Why isn't my post answered?A14. There are several possible reasons: the question is answered in the FAQ (in which case it will be ignored completely); or it involves apps or operating systems that I don't use; or it's about Gapps, which I don't use; or I simply have not had time to answer any questions.
    Q15. What speed up/optimization tips do you suggest?A15. These steps can make a big difference to performance:
    • Turn off animations. Go to Settings > System > Developer options, scroll down to the Drawing section, and set Window, Transition and Animator scale all to "Animation off".
    • Don't install Gapps unless you depend on something that only Google is providing. Use Aurora Store to get your preferred Play Store apps - they will all be available on Aurora Store. You can choose to access this anonymously or use a Google account.
    • Don't run more than two apps at the same time. You can probably listen to music in the background and use a web browser at the same time.
    • Use a web browser with built-in adblock and privacy features, such as Brave.
    • Use NewPipe to watch your streaming content. It has built in adblock so you don't have to watch forced ads.
    • Look for apps that are open source, ad-free and lightweight.
    Q16. Does this ROM support Magisk so I can root my device?A16. Magisk works with this ROM and I'm using it, but that could change with any revision and changes by Google. However I can't help with any related issues. Direct any questions about Magisk to the XDA Magisk forum.
    Q17. Will this ROM ever become official?A17. Never. Official maintainers have onerous responsibilities, and I know my device trees, code organization and git commits will NOT meet LineageOS standards. I'm not able or willing to take on the responsibilities and commit the extra time to supporting an official build.
    Q18. What is the difference between this ROM and others?A18. This ROM tries to be pure LineageOS with little or no modification. Other ROMs may come with a different UI, different bundled apps, etc.
    Q19. Will there be any major 18.1 code modifications in the future?A19. I don't anticipate any major modifications. There may be some slight tweaking to the SEpolicy, small bug fixes and minor code cleanup, but all the hard work - getting the ROM up and running, and fixing all the major bugs - has been done. This doesn't mean the code is perfect or well organized, but I won't be making any major changes.
    Q20. Why did you fork the trees?A20. I wanted my own private branch where I could make changes that would only affect my own personal builds.
    Q21. Can you build a variant of this device? For example, a S-pen version?A21. I cannot and will not try to build for a variant device if I don't physically have that device. I have to be able to boot and test it myself, and there's no guarantee that I can get those variant features working. So I will NEVER build T710, T810 and T815.
    Q22. Does this ROM have any wifi connection issues?A22. This ROM's wifi has been stable on the specified device ever since lpedia and retiredtab determined the root cause of the wifi problems back in July 2021 and re-installed the original S2 network 'blobs' with LOS 17.1.
    Q23. Is this ROM secure so I can do financial transactions?A23. Although Android monthly security patches do improve general security, this ROM's outdated kernel and old proprietary vendor blobs/drivers will NEVER get updates of any kind, and could have significant security holes.

    In addition, although the ROM is SElinux enforcing, there's a good chance that the rules written (about 800+ lines of code) have some errors.

    If the device is rooted, this would further weaken the security.

    With this information, it's up to you to make an informed decision about whether you trust this ROM to be secure enough for your financial transactions.
    Q24. Okay, I understand the consequences and willing to take the risks outlined, now where can I find the BETA ROM?A24. Downloads are at

    https://sourceforge.net/projects/los4sgt/files/los18.1/

    Please note that there are two builds for every date. Start with the enforcing build, if you hit issues, flash the permissive boot image to determine if your issue is related to SELinux. If you have Magisk installed, you first need to patch the permissive boot image with the Magisk app before flashing.

    If your initial enforcing build install does not have working RIL, you might need to fix SELinux labeling of your EFS partition. To do so, use ADB in root mode. Please note that ADB root needs to be enabled in the developer options of your device. Then use the following commands from a PC connected via ADB:

    Bash:
    adb root
    adb shell
    # Check if SELinux relabeling is required, do not modify anything
    restorecon -R -v -n /efs
    # If you see some "Relabeling..." output, run the real relabeling
    restorecon -R -v /efs
    2
    December build lineage-18.1-20221217-UNOFFICIAL-gts28ltexx.zip uploaded. Please see FAQ #24 for the download link.

    December 17, 2022 release notes:
    • December 2022 LineageOS & Android security fixes. >3800 files changed.
    If you are coming from a previous version of these builds, you can dirty flash, otherwise please perform a factory reset and format data before installing this ROM.

    Enjoy
    2
    Just to clarify, since there has been discussion about the WiFi version (t713), can this ROM be safely flashed on one?

    Also I believe I have a t715Y... Would this t715 ROM work on it?
    The T713 and T715 have completely different chipsets. T713 is msm8976 and T715 is exynos5433.

    If your T715Y is known as "gts28ltexx" OR "gts28lte" as described in post #1, then you can flash this rom on it. You can download an utility called devcheck by flar2 to verify. Your device name will be shown in the system tab under device.

    https://play.google.com/store/apps/details?id=flar2.devcheck

    metterschling's code checks for gts28lte,gts28ltexx using this below

    https://github.com/metterschlg/andr...s28ltexx/blob/lineage-18.1/BoardConfig.mk#L17