[Samsung Galaxy Tab A series Guides, News, & Discus] jedld:
UPDATE 09/20/2016 - Root is now available for the SM-T285 (custom ROM and SM-T280 to follow) see post for details (http://xdaforums.com/showpost.php?p=68777842&postcount=27)

After some work I've managed to debloat my Galaxy Tab A(6) 7.0 LTE (SM-T285/T280). We all know that with a locked bootloader we

can at least do customizations with the system partition:

Here is a simple guide with hopes that more people with the device can continue to allow for more ROM customizations:

Tools/Requirements:

================

- Ubuntu as my OS

- make sure you have adb installed and running (See the android developers guide on how to do this)

- Heimdall 1.4.1

- A copy of the stock firmware zip from samsung for your device

- 7zip to be able to unzip the firmware from above

- Android AOSP fsutils simg2img and make_ext4fs (Attached) (note that your make_ext4fs needs to be patched to be able to generate samsung patches easily see gist) for some reason samsung chose to use a slightly different sparse file layout for this device. Using the stock make_ext4fs to generate an image will cause heimdall ( ad Odin) to stop data uploads after the first packet stream.

Or if you still want to use stock make_ext4fs you can try using Chainfire's sgs4ext4fs and run this after you generate your system.img, I haven't tried this route personally myself.

Step By Step (Part 1 - Mount stock system.img for modification)

==========

1. Create a folder to do your work like samsing_kitchen for example. Place your

stock firmware package there

mkdir samsung_kitchen
cd samsung_kitchen

2. Extract your stock firmware's system.img using 7zip

7z x XTC-T285XXU0APCN-20160421170750.zip
7z x T285XXU0APCN_T285OLB0APC6_T285XXU0APCN_HOME.tar.md5

Should see a couple of image files, one of them is system.img.

3. Create mount point and convert from sparse image to mountable image and then mount it

mkdir system
simg2img system.img system.img.raw
sudo mount -t ext4 -o loop system.img.raw ./system

The contents of the system image should now be visible inside the system folder you

just created. You can now proceed to modifiying it (e.g. remove apps)

(Part 2 - Repackage image for flashing to device)

=================================================

DISCLAIMER: As always make sure you backup your important files in case

something goes wrong! I will not be responsible for any losses resulting from this

activity. Also this activity may void your warranty.

Prequisites:

- Make sure you have heimdall properly working.

- Make sure you have oem unlock. This should be visible in developer settings

To know if it is enabled/disable FRP protection should be disabled when you go

in Odin mode.

1. pull the file_contexts file from .your device ( or download the attached in this post).

adb pull file_contexts

on a connected device in developer mode. You will need this file so that the permissions are properly set when building the image

2. Exit from system back to your working folder (e.g. samsing_kitchen ) and run

the following:

sudo make_ext4fs -s -l 2147483648 -S file_contexts -a system new_system.img ./system

This should create a flashable image called new_system.img

3. Restart your SM-T285 into Odin Mode (Power-off, then hold home vol-down + power until Odin Mode shows up)

4. Flash using Heimdall

heimdall flash --SYSTEM new_system.img

Your device should automatically restart after this. If something goes wrong you can always flash the original system image back.

Making an ODIN flashable image

----------------------------------------

To create an image compatible with ODIN (tar.md5) make sure you have a copy of the stock image zip from samsung and extract (using 7zip) its contents to a folder:

An extracted file should look like this:

boot.img
cache.img
hidden.img
nvitem.bin
recovery.img
SPRDCP.img
SPRDGDSP.img
SPRDLTEDSP.img
SPRDWDSP.img
system.img

replace the stock system.img with the one you created from above:

cp ../new_system.img system.img

tar and md5 it:

tar -H ustar -c boot.img cache.img hidden.img recovery.img SPRDCP.img SPRDGDSP.img SPRDLTEDSP.img SPRDWDSP.img system.img >T285_CUSTOM.tar
md5sum -t T285_CUSTOM.tar > T285_CUSTOM.tar
mv T285_CUSTOM.tar T285_CUSTOM.tar.md5

as per ashyx this should also work as well:

tar -H ustar -c system.img > system.tar
md5sum -t system.tar > sytem.tar
mv system.tar system.tar.md5

Optionally Zip it if you want:

7z a T285_CUSTOM.zip T285_CUSTOM.tar.md5

This guide should work for the T280 as well, though I can't confirm it since I don't have access to that model.

Petition for samsung to unlock the device:

https://www.change.org/p/samsung-unlock-the-bootloader-for-the-samsung-galaxy-tab-a-7-0-2016?recruiter=286570213&utm_source=petitions_share&utm_medium=copylink

Custom ROM to enable move apps to sd (apps2sd like support):

http://xdaforums.com/android/development/rom-samsung-galaxy-tab-7-0-lte-2016-sm-t3455788