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

[zxczxc4]

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

 

[JohnTheFarm3r]

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]

@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]

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]

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.

 

[Dragon Kumera]

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]

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.

 

[AnonVendetta]

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.

 

[thatguy222]

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.

 

[thatguy222]

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.

 

[Kenaz Rune]

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]

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]

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?

 

[AnonVendetta]

I just tried the latest official Android 12L GSI. For me, it's not a keeper. After you've unlocked the bootloader and installed TWRP, flashing it is simple.

I'll go into more details later. But for now:
Double tap to wake not working
It wants me to reformat my SD card (which has several hundred GB of files on it)
There is a persistent bottom dock that I couldn't find a way to disable
The navigation buttons are wonky, recents/home/back don't work as I expect them to
Partitions like system are read only and can't be remounted read/write even with root access
Play Store says device not certified, even before rooting
Couldn't find a way to disable fast charging
The UI looks very plain, and seems to be more optimized for phones rather than tablets
Default screen orientation is portrait, not landscape. And auto rotate is disabled by default

On the upside:
Latest Magisk works out of the box, no need to use Android 10 vendor.img
Logging into Google works, no hacky workarounds necessary. The built in Google apps all work too.
MTP works out of the box, no need to use ADB to copy files
Performance is good

 

[xpdragon]

I just tried the latest official Android 12L GSI. For me, it's not a keeper. After you've unlocked the bootloader and installed TWRP, flashing it is simple.

I'll go into more details later. But for now:
Double tap to wake not working
It wants me to reformat my SD card (which has several hundred GB of files on it)
There is a persistent bottom dock that I couldn't find a way to disable
The navigation buttons are wonky, recents/home/back don't work as I expect them to
Partitions like system are read only and can't be remounted read/write even with root access
Play Store says device not certified, even before rooting
Couldn't find a way to disable fast charging
The UI looks very plain, and seems to be more optimized for phones rather than tablets
Default screen orientation is portrait, not landscape. And auto rotate is disabled by default

On the upside:
Latest Magisk works out of the box, no need to use Android 10 vendor.img
Logging into Google works, no hacky workarounds necessary. The built in Google apps all work too.
MTP works out of the box, no need to use ADB to copy files
Performance is good

Double tap to wake works fine on my device with latest GSI build v414. I had to enable it under the Treble Setting. My Play Store says "Device is Certified". I had to clear Storage and cache of the Play Store app after Magisk root though.

 

[AnonVendetta]

Double tap to wake works fine on my device with latest GSI build v414. I had to enable it under the Treble Setting. My Play Store says "Device is Certified". I had to clear Storage and cache of the Play Store app after Magisk root though.

Nice to know. But I was referring to Google's official Android 12L GSI. I used the latest version, but double tap to wake still not working. I'll try other GSIs soon though.

 

[xpdragon]

If you want to hide the taskbar of Android 12L GSI, check out this MOD.

Here is the another GUIDE to flash GSI on Galaxy Tab S7+ without TWRP. The guide is actually for Galaxy Tab A7 Lite, but it is basically the same for Galaxy Tab S7+. I found the guide is easier to follow.

 

[AnonVendetta]

I've spent the last week-ish seriously dabbling with GSIs. I've been running stock for months and decided it's time to move on. So far I've only tested Android 11 GSIs.

I've been PMing @LSS4181 off and on for awhile. At first, I had alot of trouble getting this GSI guide to work, and the last time I tried a GSI was with Google's official Android 12L, which i didnt like.

The GSIs I've tested so far are Phh's official AOSP, and Pixel Experience. Again, I've only tried the latest A11 releases.

With Phh's GSI, you can't Securize, because it will softbrick, and not even a factory reset in TWRP will fix it. But Securize isn't the real issue. On a 2nd GSI flash, i intentionally didnt Securize. Instead, I deleted Phh su's files from TWRP (there are 4 of them, located in the system img). And....same result...softbricked. So it would seem that simply removing root triggers the softbrick, not Securize (which is basically what Securize does, but i suspect it also does a little extra, but the what isn't clear to me).

I managed to fix the watchdog issue without root, easily done by mounting system as RW in TWRP and issuing a command from TWRP terminal. No custom kernel required.

For Bluetooth audio, i couldnt get my JBL earbuds to stay connected without the disable A2DP fix. they would simply repeatedly disconnect/reconnect. Now they work fine.

However the A2DP fix doesn't seem to make it possible to transfer files over Bluetooth. The tab will repeatedly disconnect/reconnect to the other device, making file transfer impossible.

Also, i cant add a fingerprint. It just assumes the Tab S7+ has a hardware fingerprint reader on the back, which it doesn't. I think all of us know by now that the reader is built into the screen. The enrollment wizard doesn't respond when I touch that are.

On the upside, face unlock works fine, and the cameras. I've also been able to add a PIN as the screen lock.

Also, there have been no system crashes, besides the one triggered by watchdog0.

I'd also like to note that Magisk works fine with A11 vendor. I used unofficial Magisk 25.2 Delta by @huskydg, instead of official Magisk. Even though @LSS4181 says that A10 vendor is needed, I have discovered otherwise. I used the vendor.img from the BUJ3 A11 firmware for the model SM-T970. If anyone else would like to try an A11 vendor with a GSI, I suggest you use the BUJ3 vendor *FOR YOUR MODEL*. Download the firmware, extract super.img.lz4. This will give you super.img. Unsparse it with simg2img. Then extract the vendor.img from super.img with lpunpack. Flash as per the command in the OP.

Another issue with using A10 vendor is that I got intermittent lag and black texture issues in 2 games. The ones I tested are Call of Duty Mobile, and Call of Duty: Warzone Mobile (the latter game isn't available to the public, participation is by invite from the devs only, because the game is in closed alpha/testing phase ATM). Especially in Warzone Mobile, some portions of the ground were colored blackish gray. The sky was also discolored in some areas. And the game was generally very dark overall. On stock, I didn't have these issues. A11 vendor fixed the texture issues.

However, some games still seemed to run sluggishly, even with the textures addressed. I've mostly been able to mitigate this by using a Magisk module called Stratosphere, and enabling gaming mode from within the module config.

I will probably move on to trying Android 12 GSIs. I've gotten A11 working OK enough (running Pixel Experience for a few days now), but it's not without downsides.

 

[LSS4181]

I've spent the last week-ish seriously dabbling with GSIs. I've been running stock for months and decided it's time to move on. So far I've only tested Android 11 GSIs.

I've been PMing @LSS4181 off and on for awhile. At first, I had alot of trouble getting this GSI guide to work, and the last time I tried a GSI was with Google's official Android 12L, which i didnt like.

The GSIs I've tested so far are Phh's official AOSP, and Pixel Experience. Again, I've only tried the latest A11 releases.

With Phh's GSI, you can't Securize, because it will softbrick, and not even a factory reset in TWRP will fix it. But Securize isn't the real issue. On a 2nd GSI flash, i intentionally didnt Securize. Instead, I deleted Phh su's files from TWRP (there are 4 of them, located in the system img). And....same result...softbricked. So it would seem that simply removing root triggers the softbrick, not Securize (which is basically what Securize does, but i suspect it also does a little extra, but the what isn't clear to me).

I managed to fix the watchdog issue without root, easily done by mounting system as RW in TWRP and issuing a command from TWRP terminal. No custom kernel required.

For Bluetooth audio, i couldnt get my JBL earbuds to stay connected without the disable A2DP fix. they would simply repeatedly disconnect/reconnect. Now they work fine.

However the A2DP fix doesn't seem to make it possible to transfer files over Bluetooth. The tab will repeatedly disconnect/reconnect to the other device, making file transfer impossible.

Also, i cant add a fingerprint. It just assumes the Tab S7+ has a hardware fingerprint reader on the back, which it doesn't. I think all of us know by now that the reader is built into the screen. The enrollment wizard doesn't respond when I touch that are.

On the upside, face unlock works fine, and the cameras. I've also been able to add a PIN as the screen lock.

Also, there have been no system crashes, besides the one triggered by watchdog0.

I'd also like to note that Magisk works fine with A11 vendor. I used unofficial Magisk 25.2 Delta by @huskydg, instead of official Magisk. Even though @LSS4181 says that A10 vendor is needed, I have discovered otherwise. I used the vendor.img from the BUJ3 A11 firmware for the model SM-T970. If anyone else would like to try an A11 vendor with a GSI, I suggest you use the BUJ3 vendor *FOR YOUR MODEL*. Download the firmware, extract super.img.lz4. This will give you super.img. Unsparse it with simg2img. Then extract the vendor.img from super.img with lpunpack. Flash as per the command in the OP.

Another issue with using A10 vendor is that I got intermittent lag and black texture issues in 2 games. The ones I tested are Call of Duty Mobile, and Call of Duty: Warzone Mobile (the latter game isn't available to the public, participation is by invite from the devs only, because the game is in closed alpha/testing phase ATM). Especially in Warzone Mobile, some portions of the ground were colored blackish gray. The sky was also discolored in some areas. And the game was generally very dark overall. On stock, I didn't have these issues. A11 vendor fixed the texture issues.

However, some games still seemed to run sluggishly, even with the textures addressed. I've mostly been able to mitigate this by using a Magisk module called Stratosphere, and enabling gaming mode from within the module config.

I will probably move on to trying Android 12 GSIs. I've gotten A11 working OK enough (running Pixel Experience for a few days now), but it's not without downsides.

Thanks for your testing. I've revised the guide a bit. Basically to reflect the fact that Magisk is now working with A11 vendor as you've confirmed.

Additionally, I've put a note regarding the soft brick issue. Most likely this is also the case for other Samsung devices as well.

 

[AnonVendetta]

Thanks for your testing. I've revised the guide a bit. Basically to reflect the fact that Magisk is now working with A11 vendor as you've confirmed.

Additionally, I've put a note regarding the soft brick issue. Most likely this is also the case for other Samsung devices as well.

Back when I was running Google's official 12L GSI, I had the stock A12 vendor, Magisk worked with that too.

I think I will avoid Phh-based GSIs that aren't pre-securized/secure variant. That would avoid the softbrick issue, and GApps would probably also work without manual certifucation. On Pixel Experience, play services/store work out of the box. Play store says the device isn't certified, but it still lets me log in.

As for the slow charging issues I told you about, I think it may be due to the charging brick I've been using since 2019. It's a 5 port charger by Anker. Up until a few weeks ago, charging was fast enough. But sometimes, it just randomly resets. I know it has done so when measurement apps report a 0mah reading. This will go on for awhile, then suddenly it will charge fine. It's probably just wearing out. So I'll either buy the same model again to test, or just go for something else. I get varying results depending on which brick I use, which is why I think this particular brick may be at fault. This tells me that it's probably not a ROM/kernel issue, since by default GSIs use the stock kernel.

I'm looking into getting a dock, but I've got a feeling they won't be compatible with the hard case I use for protection. Mostly I'd just like to use a wired headset sometimes for better audio quality. But I'd like to be able to charge at the same time. I'm satisfied overall with my JBL Tour Pro + TWS, for $180 they sound good and last all day. But at the current time, BT audio quality can't beat wired.

I'm also wondering if someone knows how to get Dolby Atmos working. In the fast-paced online games I play, directional sound can be the difference between death and survival. I really miss this feature from stock due to how useful it is.