[Samsung Galaxy Tab A series ROMs, Kernels, Recover] K9100ii:
This is LineageOS 19.1, which is based on Android 12L, for variants of the Samsung Galaxy Tab A 10.1" (2016), which have models and codenames as follows:

SM-T580, with codename gtaxlwifi

SM-T585, with codename gtaxllte, along with SM-T585N0, SM-T585C, and SM-T587 (not SM-T587P)

SM-P580, with codename gtanotexlwifi, along with SM-P583

SM-P585, with codename gtanotexllte, along with SM-P585M, SM-P585Y, SM-P585N0, and SM-P588C

LineageOS doesn't need much of an introduction - It's a well-known custom firmware/Android distribution.

For LineageOS 20.0 - Go here

Some useful information only for devices from China (Never any others!) (SM-P583, SM-T585C, SM-P588C, and SM-T580 on the CHN CSC code for China) - For unlocking the bootloader before installation, an app, "CROM Service", would need to be opened and the prompt from it accepted so that it can be unlocked, after enabling the "OEM unlock" setting in developer options. It should be available from the Galaxy Store, although I can't be 100% sure about it. In any case, an APK for it should be easy to find.

Also, for those running 18.1 or 17.1, upgrading to 19.1 is possible through the procedure I've explained before here and here. Mentioned Android/Lineage versions are different, but the steps still apply. I highly suggest backing up any important data before trying to upgrade. In the unlikely case the upgrade fails, and it doesn't boot, data would need to be formatted.

LineageOS 19.1/Android 12 usability fixes

For those wanting to disable the widely disliked taskbar (the grey bar at the bottom with the 3 navigation buttons and shortcuts for apps docked at the launcher): Instructions for doing so are in the first section of my post here.

For enabling lockscreen rotation: Instructions for doing so are in my post here.

For those needing Google apps: Do not use heavy Google apps packages, as otherwise, you WILL have severe performance issues. Instead, use the most minimal variant of your chosen package (core, pico...). Also, while mentioning that, make sure the package is 64-bit ARM (ARM64) and specifically, and only, for Android 12L.

You may look for Google app packages that others have had success using by searching the thread. Also worth considering is microG, which - if you can use and don't have anything depending strictly on having Google's own play services - will allow you to have additional resources (RAM mainly) that would otherwise be taken up by Google play services.

Build downloads - From 20240704, all with security patch level 20240605

For gtaxlwifi: https://drive.google.com/file/d/1jCwmWl22ztI9nKDXT7Dewuadfw-cwr8z

For gtaxllte: https://drive.google.com/file/d/1VllFbWqCQkjxIVjIEAOTPv3mNkWovUxb

For gtanotexlwifi: https://drive.google.com/file/d/1PyRRZbxv95s_QbnhyyFMo7E10GyuTUC3

For gtanotexllte: https://drive.google.com/file/d/1jsjWtOhstUmwZEdCwk0VyD8DkwExcRI5

Recoveries to use

Use my unofficial TWRP builds:

For gtaxlwifi: Image here, tar for Odin for AP slot is here.

For gtaxllte: Image here, tar for Odin here.

For gtanotexlwifi: Image here, tar for Odin here.

For gtanotexllte: Image here, tar for Odin here.

Official TWRP builds also work. Lineage recovery images within builds as "recovery.img" do work as well, but only for installing packages from a micro SD card.

Note that any other recoveries are completely unsupported and not recommended whatsoever.

Folders for builds

Along with current builds, these contain text files with SHA256 checksums for builds, and folders containing few previous builds.

For gtaxlwifi: https://drive.google.com/drive/folders/1S3NRiTP2jr9gRtSMKoKoaoMu75g_FJM4

For gtaxllte: https://drive.google.com/drive/folders/1ZFkGkVkIohsNFDi0jNF2-Yhz7Sbg5GT4

For gtanotexlwifi: https://drive.google.com/drive/folders/11pcp9NZf0ovelvT7oxfhoem6-utpSao8

For gtanotexllte: https://drive.google.com/drive/folders/1AICJ1UcnZ5a-slcgd-iGQ9mpk9J8Evmd

Changelogs

Builds for 20240704:

Latest updates from LineageOS, including the 20240605 Android security updates.

Builds are now signed with my own release-keys - This set contains the signing migration patch here.

Some security patches have been applied to the kernel.

Previous releases

Builds for 20240521:

Latest updates from LineageOS, including the 20240505 Android security updates (not yet merged for 19.1, so picked via repopick -t S_asb_2024-05).

A variant of the HWC bug fix I applied for 20.0, to fix random reboots after some video playback, has been applied - Should improve very long term stability.

[WiFi-only variants only] Support for Android's ConnectionService API is no longer incorrectly declared - Stops issues with apps that try to use it, only for failure since it isn't present.

Some security patches have been applied to the kernel.

Builds for 20240318:

Latest updates from LineageOS, including the 20240305 Android security updates and changes for adding restrictive signature spoofing support only for microG, replacing the patches used before.

Lineage's charging control feature, which was ported for LineageOS 19.1, has been enabled.

Some security patches have been applied to the kernel.

Builds for 20240221:

Latest updates from LineageOS, including the 20240205 Android security updates.

Long standing issues with microphone volume for video recordings being low have been fixed.

Lineage's FlipFlap has been removed - Not necessary, and all its options are now either non-functional or irrelevant.

A few security patches have been applied to the kernel.

Builds for 20231213:

Latest updates from LineageOS, with manually applied 20231205 Android security updates (from the S_asb_2023-12 topic on Lineage's gerrit site).

Recently introduced audio issues, and hopefully also all audio issues on revision 7 gtaxllte tablets, should now be fixed.

Builds for 20231013:

Latest changes from LineageOS, including the (important) 20231006 Android security updates.

Audio issues should hopefully be fixed on "exotic" hardware revision 7 T585 devices.

A few security fixes have been applied to the kernel.

Some fixes have been applied to the Sony, xpad, and Apple HID kernel drivers.

Sony's upstream hid-playstation driver has been backported for DualSense controller support.

Builds for 20230824:

Latest changes from LineageOS, including the 20230805 Android security updates.

[WiFi-only variant specific] 120+ MB of RAM has been freed for usage. (It was previously pointlessly reserved and so wasn't even reported as available.)

Possible slight graphical performance improvement? I honestly can't tell.

Builds for 20230720 and 20230722 (LTE variants only):

Latest changes from LineageOS, including the 20230705 Android security updates.

Call audio over Bluetooth has been fixed (with an additional fix for Bluetooth calls in 20230722 builds).

On tablets with different models for different regions, the correct model number should now be set and displayed in "About tablet" in settings.

[LTE variants only] RIL blobs have been updated from Samsung's A305GUBU8CWE3 firmware.

Booting and sensors issues fixed for revision 7 gtaxllte devices (exclusive to 2020 students in Egypt) - Audio issues remain (see issue 5 under issues section).

Many updates from the 4.14 Android common kernel, up to v4.14.320, and a few other small updates, have been applied to the kernel.

Builds for 20230603:

Latest changes from LineageOS, including the 20230505 Android security updates.

Incomplete support for revision 7 gtaxllte devices, which were apparently exclusively for 2020 students in Egypt, has been added. (Note: Boot image here required for a change needed to boot on the 7th revision for the 20200603 build, the change will be included in all future builds making it unnecessary for them.)

Builds for 20230419:

Latest changes from LineageOS, including the 20230405 Android security updates.

Linaro's new SLSI BSP (Board Support Package, containing sources for HWC and some other stuff) sources are now used - Much more up-to-date than the previously used sources, and there's possibly a small improvement in performance.

The OMX hardware video decoder and encoder libs are now built from the new Linaro BSP sources - With that, playback of HEVC videos is fixed in Chrome and other Chromium-based browsers.

Some updates from the 4.14 Android common kernel as of March have been applied to the kernel.

The wireguard kernel module has been added back - I silently removed it in the previous builds since it was unusable due to a now fixed device lockup bug that caused almost total unresponsiveness after enabling a wireguard VPN.

Builds for 20230128:

Latest changes from LineageOS, including the 20230105 Android security updates.

[LTE variant-specific] Issues with mobile networking not working have been fixed.

[gtanotexllte-specific] Additional issues with bootlooping and rebooting during the boot animation have been fixed.

Open source aptX encoder libraries, from sources adapted from Qualcomm's recently upstreamed to AOSP open source code, are now used.

Builds for 20221231 and 20230101:

Latest changes from LineageOS, including the 20221205 Android security updates.

Some more miscellaneous cleanups have been done.

Initial builds for gtaxllte and gtanotexllte.

Many updates from the 4.9 Android common kernel have been applied to the kernel.

Builds for 20221127:

Latest changes from LineageOS, including the 20221105 Android security updates.

Builds for 20221020:

Latest changes from LineageOS, including the 20221005 Android security updates.

Performance of animations has been improved slightly further.

Configuration files for media codecs and profiles have been updated from Samsung's M105FDDS4CVG1 firmware, and audio codec support might be improved slightly (as the Codec 2.0 media codec framework has been fixed and is now used).

Some updates from the 4.9 Android common kernel have been applied to the kernel.

Builds for 20220929:

Latest changes from LineageOS, including the 20220905 Android security updates.

The torch has been fixed.

Performance of animations and responsiveness has been improved slightly.

Some updates from the 4.9 Android common kernel have been applied to the kernel.

[SM-P580/gtanotexlwifi only, already fixed in T580 builds long ago] An issue where the displays backlight would be turned off completely when setting very low brightnesses, causing nothing to be visible on the display (unless very faintly if you shine a torch or a different bright light source on it), has been fixed.

The WiFi drivers RX wakelock feature has been disabled - Heavy battery drain that occurred in sleep when connected to certain WiFi networks due to "qcom_rx_wakelock" wakelocks has been fixed.

Builds for 20220824:

Latest changes from LineageOS, including the 20220805 Android security updates, and a fix for "Intent Filter Verification Service" crashes that occurred in few/some cases with no Google apps or with MicroG.

Some things that appeared that are only relevant for devices with mobile networking (such as the baseband version and SIM status sections in About tablet in settings) no longer appear.

The ZRAM size has been increased to 2GiB, and the swappiness is now set to 100.

A higher frequency (1246MHz, was 902MHz previously) is now set for the interactive CPU governors "hispeed_freq" value - This improves responsiveness slightly.

The sepolicy containing device-specific SELinux rules has been improved slightly.

Yet more miscellaneous cleanups have been done.

Some updates from the 4.9 Android common kernel have been applied to the kernel.

Builds for 20220724:

Latest changes from LineageOS, including the 20220705 Android security updates.

Some updates from the 4.9 Android common kernel have been applied to the kernel.

Builds for 20220620:

Latest changes from LineageOS, including the 20220605 Android security updates.

Network traffic monitoring now works (as some changes reverting the removal of the old, non-eBPF, method of doing it that the old 3.18 kernel only supports have been applied, thanks to @rINanDO for them!).

One of Lineage's changes to the default keyboard, likely to be causing a problem where the keyboard appears full screen with no keys in very few cases, has been reverted.

Many updates from the 4.9 Android common kernel, and some from a few other sources, have been applied to the kernel.

The issue where trying to power off, or reboot to recovery or download mode, would sometimes cause a normal reboot has been fixed.

A small fix to the kernel has been applied that fixes occasional soft reboots, that were caused by a change I made a very long time ago that had only started causing such soft rebooting problems with Android 12.

Builds for 20220523:

Latest changes from LineageOS, including the 20220505 Android security updates and an option for disabling the taskbar.

The problem where enabling the "Enable on-screen nav bar" option at Settings -> System -> Buttons caused touchscreen input to be disabled has been fixed.

Native support for IPsec tunnels has been enabled.

Support for Vulkan compute is now declared.

A new custom version of the open source Samsung audio HAL from Lineage's android_hardware_samsung repository is now used, rather than the stock, heavily-patched, proprietary Samsung audio HAL, with some fixes for a problem that made it unusable before where occasionally, audio would get outputted from both the speakers and the headphone jack.

The playback and low-latency capture period sizes have been reduced to 128 in the open source audio HAL, which reduces audio latency.

Pro audio support is now declared, since with the reduced period sizes, as well as with the use of the open source audio HAL, round-trip audio latency has been reduced enough for it.

Many updates from the 4.9 Android common kernel have been applied to the kernel.

Several fixes to the Sony HID driver in the 4.9 Android common kernel have been ported over to the kernel - Sony DualShock 4 controllers should now work properly.

Initial builds for 20220416 (This changelog continues on from @followmsi's last 19.1 build that was intended for use by users):

Latest changes from LineageOS.

SELinux is now set to be enforcing after having addressed new SELinux denials with 12.

Assisted GPS has been fixed.

ADB is no longer enabled by default or on boot.

The tablet product characteristic has been added back after being mistakenly removed - Places where the device was referred to as a phone (such as the "About phone" section in settings) will now refer to it as a tablet again.

The Widevine DRM blobs have been updated to 1.4 blobs from the latest stock firmware for the Google Pixel 3a XL.

A new wcnss_filter binary built from sources is now used to properly fix an issue where Bluetooth couldn't be re-enabled after enabling and disabling it once, and the old workaround for it has been removed.

Some other miscellaneous cleanups have been done.

There are a few updates from the 4.9 Android common kernel and Samsung's A600FNXXU9CVB1 kernel sources to the kernel.

An issue where the displays backlight would be turned off completely when setting very low brightnesses, causing nothing to be visible on the display (unless very faintly if you shine a torch or a different bright light source on it), has been fixed.

Known issues and workarounds/fixes (if any)

Issue 1 - Squashed (rear) camera previews, and videos at some resolutions: Camera previews for images to be taken at resolutions with aspect ratios other than 16:9 using the rear camera are squashed from 16:9 (while final saved images at any resolution are unaffected by any squashing), and videos taken at some resolutions are affected by similar issues with squashing in previews, and, in a smaller set of resolutions, also in final saved video files. (Note that these issues don't affect the front-facing camera)

Somewhat of a workaround: Use resolutions at which there are no issues with squashing from 16:9.

Issue 2 - LTE variants - In-call echo: There may be echoing that can be heard by the person you're calling while using speakers.

See my post here for more on this issue.

(Temporary) Issue 3 - APN issues on LTE variant devices - after installation of a proper LTE variant build on top of an installation previously from a WiFi-only build: On an LTE variant device, after installing a proper LTE variant build on top of an existing installation from a WiFi-only build, when going to APN settings, at Settings -> Network and Internet -> SIMs -> Access point names, an error is displayed that APN settings cannot be changed by the current user (or something similar).

Fix: Tap the 3-dot menu at the top right, and select "Reset to default", and then select the relevant APN.

Issue 4 - LTE variants - No VoLTE (and VoWiFi) support: VoLTE, and likewise VoWiFi, currently cannot work on any Samsung devices due to Samsung's proprietary implementation in stock firmwares not working on AOSP.

Issue 5 - Only on 7th revision gtaxllte devices which were exclusive to 2020 students in Egypt:

Emphasizing the exclusivity of the 7th revision - You'll likely know if you have such a gtaxllte/SM-T585 device by it!

If you want to be sure, run this command in a terminal app (such as Termux) or ADB shell on Samsung's stock firmware, which will return "7" if you have a revision 7 tablet - getprop ro.boot.hardware.revision

If you don't, you won't have this issue:

As headphones are plugged in, and audio is played from speakers, audio will be outputted from both headphones and the speakers. After a few seconds of pausing any audio, there won't be any audio output at all.

This issue can apparently somehow be bypassed by using audio effects apps, such as Viper4Android. Real fix for things to work properly without anything extra is desirable but not yet known.

Hopefully gone with the 20231213 gtaxllte build onwards. Apparently not, sadly.

Something notable is that with Android 12, encrypted data can't be decrypted in TWRP recovery. That problem can only be fixed within TWRP, but with the fixes only being in Android 12L TWRP sources, which we can't build our TWRP builds from due to issues, it continues to exist.

To report further issues, get a log from logcat and dmesg. If you're unsure on how to get either, there's good documentation out there for how to do so.

Sources

A manifest containing all of the necessary repositories to make builds for all of the variants is in the repository here on branch lineage-19.1.

Thanks to:

@Valera1978 - for all of the previous work for the T580 and T585 long ago.

@followmsi - for previously working with me on much of this stuff.

Anyone who has previously tested anything new I've put up for testing, reported results, and provided information needed for me to get it working if it was necessary.

The Lineage team - for the Android distribution itself.

...and everyone else who has worked on anything that is in use.