[Samsung Galaxy A21s Guides, News, & Discussion] Wer99:
Easy to way to install a GSI on your Samsung A21s without installing a Virtual Linux.

NFC, Screen Cast, and USB MTP unfortunately is not working with AOSP 10 and 11. Backup all your data.

If don't want to make one, download my Pre-Rooted GSIs below and flash.

*Unlock your Bootloader and wipe your data using your stock recovery and quickly boot to Download Mode and flash the super.tar on Odin (AP):

Android 10 -> Download (MediaFire)
Android 11 -> Download (MediaFire)
Android 11 - AOSP 11.0 v306 -> Download (MEGA) - NEW
Android 10 Screenshots

1. Requirements:​

1. Unlock your Bootloader
2. Download and Install a Linux Subsystem -> Ubuntu Subsystem -> "Tutorial How to install Linux Subsystem on Windows 10 | or search how to"
3. GSI Android 10 A/B Gapps -> Download only the "arm64, A/B". I recommend releases from Treble Experimentations AOSP like "system-roar-arm64-ab-gapps.img.xz".
4. Samsung.zip -> There's all needed tools and files - Odin, 7-Zip ZS etc...

- Download Samsung.zip and extract the folder "Samsung" to your desktop, and extract your chosen GSI using to this folder.

- Download your stock firmware and extract the super.img.lz4 file from AP_A217XXXXXXXXXX_XXX_XXXX_REV00_XXX.tar.md5 with 7-Zip ZS.

- Now extract super.img.lz4 using 7-Zip ZS (don't use 7-zip) to Samsung folder. Rename super.img to stock_super.img.

2. Convert stock_super.img to raw_super.img:​

Open CMD ad use this codes:

cd C:\Users\%USERNAME%\Desktop\Samsung
simg2img.exe stock_super.img raw_super.img

Wait...

3. Extract raw_super.img:​

On your Samsung folder, use SHIFT key of your keyboard + right click and click at "Open Linux Shell Here", wait a little, and use this code and wait the extraction:

./lpunpack --slot=0 raw_super.img

*If the extraction is completed, verify if there's this files odm.img, system.img, vendor.img and product.img. Delete or rename system.img and product.img, then extract your GSI to Samsung folder and rename the xxx.img file to system.img.

4. Pack all the files and Flash:​

No math here! Just use this code on Terminal and wait (Ignore errors like "Partition system, vendor, odm will resize..." or "Invalid sparce file format at header magic...")

./lpmake --metadata-size 65536 --super-name super --metadata-slots 2 --device super:5557452800 --group main:3819597824 --partition system:readonly:3340271616:main --image system=./system.img --partition vendor:readonly:474976256:main --image vendor=./vendor.img --partition odm:readonly:4349952:main --image odm=./odm.img --sparse --output ./super.img

Wait....

Use 7-Zip to archive the super.img to .tar (super.tar) and flash it on Odin (AP) and wait the phone to boot.

Unlock your Bootloader and wipe your data using your stock recovery and quickly boot to Download Mode and flash the super.tar on Odin (AP):

Notes:​

I not responsible for any damage on your phone. If anything occurs, just flash your stock regional firmware through Odin.

If this tutorial did not work, you did something wrong or your phone is not supported. Don't forget to wipe your data through Recovery, it's very important.

If you want Magisk working on your A21s I recommend you to report to an issue Topjohnwu at Github.