Backup of the original OS, before installing /e/

beposanfior · February 10, 2021, 9:58am

Dear all,

I bought a Samsung Galaxy S7 (SM-G390F as it is a supported device) and I would like to try /e/ on it, but before doing it I would like to know if and how I can make a copy of the original OS. The idea is to be able to revert back to the original OS if I need.
I already had a look at this guide, but as far as I understood by installing/flashing TWRP I will loose the original OS.

Any help/suggestion on this topic is very welcome.

Regain your privacy! Adopt /e/ the unGoogled mobile OS and online services phone

mcmd · February 10, 2021, 12:25pm

Hello @beposanfior. I too had the same concerns regarding my S9. According to @SuzieQ, there is no good way to do this beforehand. She suggests that if you ever wish to revert back to stock, to download and install the stock ROM for your device which can be found at sammobile.com or samfrew.com.

Hopefully she will come along and confirm!

SuzieQ · February 10, 2021, 2:08pm

Hello @mcmd,
Samsung’s Galaxy S7 ‘herolte’ is not really comparable to the Galaxy S9 ‘starlte’. The S7 with stock Android 8-Oreo can be flashed immediately with /e/ OS 'O’reo 8.1.2 ‘stable’ or ‘dev’. No downgrading or upgrading is required.

Hello @beposanfior,
it is obvious that you ‘will lose the original OS’ if you install a customROM like /e/ OS. Therefore, important data should be backed up externally beforehand. However, a return to the stock Android 8 Oreo is possible at any time.

mcmd · February 10, 2021, 2:24pm

Thank you for clarifying @SuzieQ, most appreciated. If I have understood your other posts on this subject correctly, Samsung made significant changes to the bootloader starting with the S9 that are not present in prior Galaxy versions.

SuzieQ · February 10, 2021, 2:48pm

The S7 was released with Android 6.0 (Marshmallow), the S8 with Android 7.0 (Nougat), the S9 was release with Android 8.0 (Oreo). With each release, Samsung has tightened the thumbscrews and built in so-called security layers and bootloader locks. This continues with Samsung up to now with Stock Android 10. Among other things, the “OEM unlock” was hidden and several operations have to be carried out to make it visible. I wouldn’t be surprised if Samsung completely removes the “unlock” from future devices and, like Huawei, completely closes the bootloader.

mcmd · February 10, 2021, 2:55pm

That does seem to be the trajectory of things. Do you have a sense as to the motivation for manufacturers to do this? Is there something specific at work here or is it just something more general: the corporate desire to lock down their devices so as to “lock” their customers “in”?

beposanfior · February 10, 2021, 3:03pm

Hi @SuzieQ, @mcmd,

thanks a lot for the answers/clarifications.

Concerning this

I could have ask in a better way: is there a way to install TWRP and than make a backup of the original OS/firmware? Or do I have to find the firmware actually installed, download it and re-installing it (i.e. via Odin or heimdall)? I don’t have a Windows pc, so do you recommend heimdall?

which way do you recommend to install /e/ OS? This one

https://doc.e.foundation/devices/herolte/install

or that one

[HOWTO] install /e/ on a Samsung device from a GNU/Linux PC successfully

do I have to worry about dm-verity? I asked here, but I’m not convinced by the answer from @piero

Thanks again!!

SuzieQ · February 10, 2021, 3:28pm

In what context have you been confronted with dm-verity? What makes you think you might have to worry about dm-verity?

beposanfior · February 10, 2021, 3:33pm

I just read about it here:

https://twrp.me/samsung/samsunggalaxys7.html
This device uses dm-verity!
This means that swiping to allow system modifications will prevent you from being able to boot if you are using the stock kernel. In order to bypass dm-verity’s boot prevention, you will have to install a kernel that has dm-verity disabled in the fstab.

As I have no experience with smartphones, I prefer to ask before messing up.

SuzieQ · February 10, 2021, 3:48pm

Ahh, this hint from TWRP is already found on the Galaxy S6, although I’ve never encountered dm-verity there before. So far, I have also changed the operating system on dozens of S7 / S7 Edge devices and have not had to undo dm-verity on any of them. Flashing the S7 usually goes off without a hitch.

beposanfior · February 10, 2021, 4:52pm

Lovely, thanks.

Any advice on point 1(based on your experience is it better to flash the original firmware from Windows?) and 2 (if you followed any of those guides)?

SuzieQ · February 10, 2021, 5:56pm

With Windows Odin 3, it’s a piece of cake.