[GUIDE][A10/A11] Flashing and booting GSI on Galaxy Tab S7+

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zxczxc4

Member
Nov 17, 2011
15
4
Something very strange:
I had previously said that I did not have any watchdog issues, but I was wrong.

I messed up doing a Magisk downgrade and restored a backup from TWRP, of my super partition, boot, recovery, etc.
After this, I started getting a reboot after 100 seconds... did the watchdog fix via Termux and that works.
Rebooted a bunch of times, each time needed the fix.
I restored the same backup again, and this time the watchdog wasn't giving issues.
Installed Magisk (backup was before I installed it) - and the reboots started again.
Currently, I am not experiencing the issue.

I may have gotten mixed up exactly what I did and when, but it at least shows that there the watchdog issue is more complex than previously thought.

I'm on a T970 and the two custom kernels (amnesty and dragkernel) that we have do not work for me.
Hopefully they will support this model soon so the whole issue stops for good :)
 
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ekin_strops

Senior Member
Apr 29, 2016
1,031
393
Munich
OnePlus 9 Pro
Doubt anyone will support this much. The issue with these expensive tablets is that not "many" people own them. Rarely do some good devs pop up and happen to own the same device and want to work on it. It's similar like the phones, check the custom ROM communities for example for Samsung phones, and check the same with XIAOMI. Xiaomi has far more devs around and the devices are "more" popular due to their more or less good price-performance ratio.
 

zxczxc4

Member
Nov 17, 2011
15
4
@ekin_strops - I agree and I knew this would be the case when I got the tablet.
Thankfully the watchdog issue is minimal, GSIs are working great, I don't regret a thing :)
 

zxczxc4

Member
Nov 17, 2011
15
4
One thing I meant to ask about, will the S Pen charge?
It works (shows up as a mouse/cursor in the LineageOS GSI that I'm using), but have no idea about the battery of the pen or if it is charging when I put it at the back of the tablet.
 

AnonVendetta

Senior Member
Apr 29, 2016
1,086
426
Portland, OR
Doubt anyone will support this much. The issue with these expensive tablets is that not "many" people own them. Rarely do some good devs pop up and happen to own the same device and want to work on it. It's similar like the phones, check the custom ROM communities for example for Samsung phones, and check the same with XIAOMI. Xiaomi has far more devs around and the devices are "more" popular due to their more or less good price-performance ratio.
I wouldn't call myself an experienced dev, but what I do have is motivation, lots of free time, and technical inclination/aptitude. I actually bought this tab with development in mind. I knew I wouldn't want to run the stock firmware forever, and I also knew that I would eventually want to root/install TWRP/etc.

When I buy a new Android device, I always check to see if it can be bootloader unlocked. And ideally, that it has a working root/TWRP method. If none of these are the case, I won't buy, simple as that. I'm old school, I believe that the user of the device should be able to change the hardware/software however they see fit. They paid for it, after all.

I just think it's BS that mobile users have to deal with locked bootloaders, but no such thing exists on PC. And, root access is accessable in Linux distros by default, but on mobile they want you to believe that root is a security risk. As long as it is used responsibly, in the hands of a knowledgeable user, things will generally be fine (excluding the possibility that a malicious person could exploit your root to do bad things).

And since I personally own a Tab S7+, that would make development a bit easier, being able to do my own tests without relying on the results/reports of others.

My only real issue with developing for this device, is that I'm not sure where to start, or what other areas of knowledge would be most beneficial as prerequisites to development.

I plan to keep this device for no less than 3 years, I'm in it for the long haul. I have a tendency to run my hardware into the ground, and won't give them up until they stop working. Even after all these years, I'm still using a Galaxy Note 4 as my daily driver phone, but it's getting long in the tooth, and it's just about time to move on.

When Samsung has terminated support for this tab and is no longer giving us new Android versions, I'll hopefully still be using it. Unlike many others, I don't upgrade to the latest and greatest hardware as they're released. Which means that by the time the majority of our tab's users/devs have moved on, I'll probably be the last active dev for it.
 
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Dragon Kumera

Senior Member
Mar 14, 2019
323
104
I wouldn't call myself an experienced dev, but what I do have is motivation, lots of free time, and technical inclination/aptitude. I actually bought this tab with development in mind. I knew I wouldn't want to run the stock firmware forever, and I also knew that I would eventually want to root/install TWRP/etc.

When I buy a new Android device, I always check to see if it can be bootloader unlocked. And ideally, that it has a working root/TWRP method. If none of these are the case, I won't buy, simple as that. I'm old school, I believe that the user of the device should be able to change the hardware/software however they see fit. They paid for it, after all.

I just think it's BS that mobile users have to deal with locked bootloaders, but no such thing exists on PC. And, root access is accessable in Linux distros by default, but on mobile they want you to believe that root is a security risk. As long as it is used responsibly, in the hands of a knowledgeable user, things will generally be fine (excluding the possibility that a malicious person could exploit your root to do bad things).

And since I personally own a Tab S7+, that would make development a bit easier, being able to do my own tests without relying on the results/reports of others.

My only real issue with developing for this device, is that I'm not sure where to start, or what other areas of knowledge would be most beneficial as prerequisites to development.

I plan to keep this device for no less than 3 years, I'm in it for the long haul. I have a tendency to run my hardware into the ground, and won't give them up until they stop working. Even after all these years, I'm still using a Galaxy Note 4 as my daily driver phone, but it's getting long in the tooth, and it's just about time to move on.

When Samsung has terminated support for this tab and is no longer giving us new Android versions, I'll hopefully still be using it. Unlike many others, I don't upgrade to the latest and greatest hardware as they're released. Which means that by the time the majority of our tab's users/devs have moved on, I'll probably be the last active dev for it.
Ya i Prob will still be on it to. I am not a dev but am willing to try being a tester :). Though Stock im happy with for now on my tab s7+. Plus its getting 3 os upgrades as well as 2 yr security patches after. So like 5 yr support.

I would still be running galaxy note 4 but mine was sprint locked and had no choice but to upgrade to unlock version cause moved to verizon. I am using pixel xl gen 1 now still and got it on android 11 (pixel experience).

I hope tab s7+ has a long life. I hate the new tablets with notch. Like there no need at all.
 

LOSXDA98

New member
Feb 16, 2022
4
0
So I am new (to this forum and to custom ROM's etc).

I can follow guides enough to install Official builds of custom ROMs, but this seems a lot more complicated and I don't fully understand the process. I think this is beyond my capabilities, but may try to learn.

But is the MTP still not working as well as bluetooth Audio and USB audio? Kind of hard to use only native speakers.
 
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AnonVendetta

Senior Member
Apr 29, 2016
1,086
426
Portland, OR
So I am new (to this forum and to custom ROM's etc).

I can follow guides enough to install Official builds of custom ROMs, but this seems a lot more complicated and I don't fully understand the process. I think this is beyond my capabilities, but may try to learn.

But is the MTP still not working as well as bluetooth Audio and USB audio? Kind of hard to use only native speakers.
MTP not working wouldn't be a huge deal for me, can always use ADB to push/pull files if needed. Or copy files to external HDD/flash drive, there are adapters out there that let you connect these to a phone/tab.

Bluetooth audio not working would be more of a dealbreaker, I use my wireless JBL earbuds for alot of things. Gaming, podcasts, watching videos, etc. I think the biggest downside of trying a GSI, is no native Dolby Atmos for surround sound, which the stock firmware has built in.
 
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To fix the Bluetooth issue on GSI ROMs (use Pixel Experience GSI by ponce) go to Settings > Phh Treble Settings > Misc Features > Force-disable A2DP offload and give the tablet a restart. That should fix it. Please reply back here if it did, so others know whether this is still a problem.
 
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Pixel Experience GSI on the Tab S7+ rocks. Took me a while to get it installed but once I did, everything works except the whole screen brightens for an instant when a fingerprint is read (I know someone just solved this with the Zenfone 8, so it is possible this will get fixed) and Face Unlock just does not work, it constantly says something about a partial face.

During set up, choose to set up unlocking later or you'll get stuck trying to set up Face Unlock. I'm sure Ponce will fix this, 402.1 is the first version with Face Unlock so there was bound to be issues.

And the Bluetooth solution I posted above does fix the Bluetooth connectivity issue. I have now verified that.
 
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Kenaz Rune

Senior Member
Mar 29, 2019
108
28
I wouldn't call myself an experienced dev, but what I do have is motivation, lots of free time, and technical inclination/aptitude. I actually bought this tab with development in mind. I knew I wouldn't want to run the stock firmware forever, and I also knew that I would eventually want to root/install TWRP/etc.

When I buy a new Android device, I always check to see if it can be bootloader unlocked. And ideally, that it has a working root/TWRP method. If none of these are the case, I won't buy, simple as that. I'm old school, I believe that the user of the device should be able to change the hardware/software however they see fit. They paid for it, after all.

I just think it's BS that mobile users have to deal with locked bootloaders, but no such thing exists on PC. And, root access is accessable in Linux distros by default, but on mobile they want you to believe that root is a security risk. As long as it is used responsibly, in the hands of a knowledgeable user, things will generally be fine (excluding the possibility that a malicious person could exploit your root to do bad things).

And since I personally own a Tab S7+, that would make development a bit easier, being able to do my own tests without relying on the results/reports of others.

My only real issue with developing for this device, is that I'm not sure where to start, or what other areas of knowledge would be most beneficial as prerequisites to development.

I plan to keep this device for no less than 3 years, I'm in it for the long haul. I have a tendency to run my hardware into the ground, and won't give them up until they stop working. Even after all these years, I'm still using a Galaxy Note 4 as my daily driver phone, but it's getting long in the tooth, and it's just about time to move on.

When Samsung has terminated support for this tab and is no longer giving us new Android versions, I'll hopefully still be using it. Unlike many others, I don't upgrade to the latest and greatest hardware as they're released. Which means that by the time the majority of our tab's users/devs have moved on, I'll probably be the last active dev for it.

I am saddened that most people aren't old school about device ownership .

If you are interested in getting a start, talk to magendanz . He built the SM-T510 ROM I use. Maybe he knows someone who can collaborate with you. He's working on an A12 version now.
 

Bologner

Member
Nov 19, 2009
31
9
I'm interested to see how the S7+ works on the 12.1 (12 L) GSI that is supposed to have better tablet/foldable feature. If anyone flashes it, give us an update!
 

LOSXDA98

New member
Feb 16, 2022
4
0
Since it doesn't look like anything official is coming out for this tablet anytime soon I am getting closer to trying to load a GSI but a lot of it I still don't know how to perform. I assume it is simple for those in the know, but I don't know what I don't know. So is there anyone that could make a video going through the process, or maybe point me in the direction of some guides so I can learn the different steps?
 

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    Code:
    /*
    * Your warranty is now void.
    *
    * I am not responsible for bricked devices, dead SD cards,
    * thermonuclear war, or you getting fired because the alarm app failed. Please
    * do some research if you have any concerns about features included in this ROM
    * before flashing it! YOU are choosing to make these modifications, and if
    * you point the finger at me for messing up your device, I will laugh at you.
    */

    This is tested on my SM-T976B, but I think the same should work on other models as well.

    1. WARNING AND DISCLAIMER
    Just unlocking the bootloader will not trip the warranty bit yet, so you can still go back at this point.
    The warranty bit will be tripped (0x1) as soon as you actually try flashing something unofficial via Odin. YOU HAVE BEEN WARNED.

    Make sure you back up all the important files in your internal storage, as you need to disable encryption with Multi-Disabler in order to let TWRP access the data partition, which would require you to format the data partition (wiping everything in the process). Additionally, keep a few nandroid backups with you so you can recover yourself in case something goes wrong.

    2. Requirements
    - Bootloader unlocked
    - ianmacd's TWRP
    - Neutralized vbmeta*
    - vendor.img from Android 10 stock FW (I used ATK3, but any A10 vendor should do)
    - Multi-Disabler

    * An empty vbmeta is not recommended. You need to patch the vbmeta of the stock FW you're currently on.

    3. Flashing
    Since this device uses dynamic partitions. Flashing system images is not as straightforward as before but not impossible.

    azteria2000's GSI Flasher provided a good example on how to use dd/simg2img to flash dynamic partitions using just recovery. This is extremely helpful, as TWRP currently doesn't support fastbootd, which would make flashing even easier.

    (1). Extracting Android 10 vendor.img
    While you can boot recent GSIs with Android 11 vendor, Magisk currently doesn't work with it. Android 10 vendor is required for Magisk to work properly.
    The Android 10 vendor can be extracted from the factory image's super.img. You need to unsparse the image using simg2img then use lpunpack to extract it, and you'll obtain the vendor.img.

    (2). Flashing GSI and Android 10 vendor.img
    The entire flashing process can be done from TWRP.
    NOTE: If you're still on Android 10 (ATK3 or earlier), you can skip flashing vendor and only flash GSI system image.
    NOTE 2: At present, Multi-Disabler expects /system_root to be mountable r/w, which cannot be done with a non-vndklite GSI. As such, if you're about to flash /vendor at this step, use a vndklite GSI, or if you're coming from stock, flash Multi-Disabler before actually flashing GSI (a reboot is needed after flashing /vendor to make it accessible).

    The corresponding block devices for system and vendor are as follows:
    Code:
    /dev/block/dm-0 - system
    /dev/block/dm-1 - vendor
    First set the block devices to r/w so you can flash images.
    Code:
    # blockdev --setrw /dev/block/dm-0
    # blockdev --setrw /dev/block/dm-1
    Now actually flash the images with dd. Change the "if" parts to point to where the GSI system image and Android 10 vendor image are.
    Code:
    # dd if=<GSI image here> of=/dev/block/dm-0 bs=1m
    # dd if=<vendor image here> of=/dev/block/dm-1 bs=1m
    In rare cases that the GSI image you're about to flash is sparsed, run the following command instead of dd. You need to point to your sparsed GSI image here.
    The vendor.img you obtain from super.img is not sparsed and can be flashed directly using the dd command above.
    Code:
    # simg2img <sparsed GSI image here> /dev/block/dm-0
    If nothing goes wrong, you've flashed the GSI as well as Android 10 vendor.
    Android 10 vendor flashed this way will work even if you have upgraded past BUC1 (which blocked the downgrade to Android 10).
    It's advised to reboot recovery before trying to access system and vendor, to avoid potential issues.
    NOTE: If you flashed vendor in this step, DO NOT REBOOT TO SYSTEM JUST YET.

    (3). Flashing Multi-Disabler

    You need to flash Multi-Disabler to disable encryption of internal storage so TWRP could access it.
    If you flashed the vendor.img when flashing GSI, you MUST flash Multi-Disabler again if you have already disabled encryption with it before.
    After flashing Multi-Disabler, you can now try booting to see if the GSI of your choice works.

    4. Important Notes
    (1). Neutralizing Software (Platform) Watchdog

    There's a software (platform) watchdog that by default doesn't get fed while running GSI, causing system to reboot about 100 seconds after boot due to "platform watchdog bite". See this issue and this issue for details.
    It's possible to disable this watchdog after boot, by executing the following command using a root shell.
    Code:
    # echo 'V' > /dev/watchdog
    You need to look for a way to execute the command above at boot to automatically disable the problematic watchdog so the GSI can function normally. There are several ways to do this, like putting the command into a Magisk module's service.sh so it gets executed when the Magisk module loads.
    EDIT: I've filed an issue regarding the matter here. After some testing, it seems /dev/watchdog0 is the real culprit for our device. Disabling either /dev/watchdog or /dev/watchdog0 will work this around.
    UPDATE (2021-09-11): I can confirm that DragKernel is not affected by this issue. The offending watchdog is not present and the system won't reboot after 100 seconds.

    (2). Uncertified Device
    Since phh-AOSP v303 and onwards, the device is considered uncertified which will prevent you from logging in to your Google account.
    Manually registering the device is required for using Google Play Services, but for some reasons that didn't work for me, so I recommend using NanoDroid with microG if applicable (requires Magisk).

    (3). Offline Charging Icon
    With some GSIs, when powered off, plugging in the charger would make the tablet enter a screen with a white charging battery icon in the middle, that I couldn't easily get out of by pressing POWER button alone. Although I did manage to get out of that screen and boot to the system, I don't really know which button combination is required, and how long I should be holding them. So for now, charging while powered off is not advised...

    5. Working Stuffs
    - 120 fps working (by forcing FPS using Phh-Treble Settings).
    - Wi-Fi and Bluetooth work fine.
    - S-Pen works as a pointer device.
    - Alternate Audio Policies (from Phh-Treble Settings) is needed to get audio out through USB Type-C.
    - Front and rear camera appears working.

    6. Not Working Stuffs
    - MTP does not appear to work properly for some reasons. You'll need ADB for transferring files.
    - USB Type-C audio adapters may or may not work depending on GSI, Kernel or maybe other aspects.
    - Bluetooth audio currently has issues that cause the system to freeze.

    7. Untested Stuffs
    - Haven't tested telephony-related stuffs as I'm not using a SIM card on the tablet yet.
    - Haven't tested fingerprint sensors as I'm not using it.

    There are still some functionalities I haven't tested yet, but anyone is free to test if you want to use a GSI.

    Special thanks to: ianmacd, phhusson, Bushcat, Vntnox, azteria2000, dron39 and many more...

    Original GSI progress issue: here
    2
    Doubt anyone will support this much. The issue with these expensive tablets is that not "many" people own them. Rarely do some good devs pop up and happen to own the same device and want to work on it. It's similar like the phones, check the custom ROM communities for example for Samsung phones, and check the same with XIAOMI. Xiaomi has far more devs around and the devices are "more" popular due to their more or less good price-performance ratio.
    I wouldn't call myself an experienced dev, but what I do have is motivation, lots of free time, and technical inclination/aptitude. I actually bought this tab with development in mind. I knew I wouldn't want to run the stock firmware forever, and I also knew that I would eventually want to root/install TWRP/etc.

    When I buy a new Android device, I always check to see if it can be bootloader unlocked. And ideally, that it has a working root/TWRP method. If none of these are the case, I won't buy, simple as that. I'm old school, I believe that the user of the device should be able to change the hardware/software however they see fit. They paid for it, after all.

    I just think it's BS that mobile users have to deal with locked bootloaders, but no such thing exists on PC. And, root access is accessable in Linux distros by default, but on mobile they want you to believe that root is a security risk. As long as it is used responsibly, in the hands of a knowledgeable user, things will generally be fine (excluding the possibility that a malicious person could exploit your root to do bad things).

    And since I personally own a Tab S7+, that would make development a bit easier, being able to do my own tests without relying on the results/reports of others.

    My only real issue with developing for this device, is that I'm not sure where to start, or what other areas of knowledge would be most beneficial as prerequisites to development.

    I plan to keep this device for no less than 3 years, I'm in it for the long haul. I have a tendency to run my hardware into the ground, and won't give them up until they stop working. Even after all these years, I'm still using a Galaxy Note 4 as my daily driver phone, but it's getting long in the tooth, and it's just about time to move on.

    When Samsung has terminated support for this tab and is no longer giving us new Android versions, I'll hopefully still be using it. Unlike many others, I don't upgrade to the latest and greatest hardware as they're released. Which means that by the time the majority of our tab's users/devs have moved on, I'll probably be the last active dev for it.
    2
    As I know, you can't. All android 10 bootloaders are XXU1 - if you upgraded to XXU2 then nothing can be done.
    Sorry, didn't notice there were new posts in my actual thread...

    While you certainly can't flash XXU1 firmware via Odin once you upgraded to XXU2, you can follow the instructions to use dd in TWRP to flash the logical partitions. This is how I used to flash vendor image extracted from Android 10 FW, as due to SELinux policy issues, Android 11 vendor does not work well with GSIs on Samsung Qualcomm devices in general. Magisk won't work, and the tablet would semi-brick if you attempt to use Securize from Phh-Treble settings.

    While I mostly use Android 11 GSIs, the same should work with Android 10 GSIs of your choice, but I haven't tested, as most A10 GSIs are no longer maintained. GSI image of your choice (/system) and A10 vendor (/vendor) are all you need, as GSIs do not care about /odm and /product so it's safe to leave them as-is.

    A WARNING: I DO NOT recommend flashing A10 stock FW using this method as you're literally violating the rollback protection which has the risk of causing A HARD BRICK!!! Similar cases have happened on other devices of other vendors before.

    ONE MORE WARNING: Due to the ongoing case of Samsung disabling cameras on Z Fold 3, I seriously advise against upgrading the device any further, especially in case a XXU3 firmware comes out in the future, as there are potential signs that such crippling behavior might spread to existing devices.
    2
    @LSS4181 - thank you for the guide, I've had a T970 for nearly 1 year now, always wanted to run a custom rom on it!


    I've tried your guide twice now, but it results in failures for me.
    I've unlocked the bootloader, flashed TWRP (twrp-gts7xl-3.5.0_10-A11_3_ianmacd.img), running ATK3.
    Not sure if TWRP for Android 11 and ATK3 being Android 10 makes a difference?

    I extracted a vbmeta.img.lz4 from the ATK3 pack online, decompressed it to get the vbmeta.img, and wrote 0x03 to decimal offset 123.
    (Tried to follow the instructions exactly)

    I think it's the flashing/dd part.
    After I dd the gsi img to dm-0, I can not reflash the multidisabler anymore. It tells me something like:
    "Failed to mount '/system_root' (Invalid argument)"
    Then, I can't even mount 'system' in TWRP, the checkbox is unselectable.

    To get back to a working state, I have reflashed the stock rom (ATK3).

    The GSI I tried to use was: system-roar-arm64-ab-vanilla.img.xz - from AOSP 11.0 v313
    Is this the correct version to use (A, A/B etc?)
    And how can I tell if the image file is sparsed or not?


    Any input is appreciated, thank you!
    Uh... I should have mentioned earlier. Multi-Disabler expects /system_root to be mountable r/w, which cannot be done with a non-vndklite GSI.

    As such, to disable encryption, you'll initially need to flash a vndklite GSI, or simply just do that before you actually flash the GSI (stock ROM can be mounted r/w). As Multi-Disabler is only needed once per /vendor flash, you'll be able to use non-vndklite GSI afterwards.

    EDIT: If you are experienced in modifying recovery zips, you can edit the Multi-Disabler install script and comment out the parts actually involving /system or /system_root.

    EDIT 2: I just realized this... I recall that phh AOSP GSI is sparsed. You need to use simg2img command instead of dd to flash it.
    2
    Thank you @LSS4181 for the exquisitely detailed instructions! I think have enough experience with this stuff to be succesful, but have not yet bought this tablet to try it (currently using a rooted, debloated S6).

    Questions:
    • Which vendor does it ship with? ATK3? I wouldn't do any upgrades when I got it, but would immediately start flashing.
    • Has anyone succesfully used XPrivacyLua (XPL) on this? I currently use XPL Pro, and I know that it depends on a working EdXposed (or Lsposed, which I've never used) which requires a working Magisk. From reading this thread, the Magisk part seems Okay, but what about Ed/L Xposed?
    Thanks again.
    XPrivacyLua/LSPosed does work, I'm able to pass safetynet thanks to it