Android 11 samsung galaxy S21 Ultra - custom boot stuck
Min Chow
I am trying to do some customization on S21 Ultra 5G SM-G998B
The source code is obtained from Samsung open source (SM-G998B_RR_Opensource.zip - G998BXXS2AUBB)
Firmware G998BXXS2AUBB_G998BOXM2AUBB_.zip is downloaded from sammobile
Step 1) Extract boot.img from firmware
The boot.img is extracted from the firmware's AP_G998BXXS2AUBB_CL20701476_QB38432109_REV01_user_low_ship_MULTI_CERT_meta_OS11.tar (using 7-zip and unpack with lz4)
The boot.img is then unpacked as follows:
$ ./unpack_bootimg.py --boot_img ./sambootimg/boot.img --out ./out
boot_magic: ANDROID!
kernel_size: 28807680
ramdisk size: 697174
os version: 11.0.0
os patch level: 2021-03
boot image header version: 3
command line args: androidboot.selinux=permissive
This step will output the following files: kernel, ramdisk and mkbootimg_args.json
Step 2) Building kernel
After building the samsung open source kernel (no changes have been made to Kernel code), the Image is obtained at arch/arm64/boot
I understand that Android 11 is based on ver 3 header. The boot.img only consists of Kernel and ramdisk
Step 3) Make boot.img
This kernel image (Image) together with ramdisk is created as follows:
$ ./mkbootimg.py --kernel ./myBootimg/Image --ramdisk ./out/ramdisk --header_version 3 --os_version 11.0.0 --os_patch_level 2021-03 --cmdline androidboot.selinux=permissive --out ./myBootimg/boot.img
$ tar -cvf boot.img.tar boot.img
This created boot.img.tar
Step 4) Magisk patch
After tar, this boot.img.tar is patched according to the magisk procedure which gives magisk_patched-22006_CjCUM.tar
The patched download to phone via the Odin utility successfully
After phone restart, it hang at Samsung screen (with the Android robot)
Can someone advise if I missed out any other important steps?
regards
Min