Teclast T40 Pro (T1B1 model) - Problems with vbmeta

jazzk
Enthusiastic Member

9

08-07-2022, 05:49 PM

#1

Hi,

I'm trying to flash a custom vbmeta and magisk-patched boot to my T40 Pro (Unisoc T618). It is Android 10 (so super partition and no separate recovery partition). My bootloader is unlocked.

I've tried creating a custom vbmeta image using the excellent guide here, but the tablet does not boot after I've flashed it.

Attached are the stock vbmeta and my custom vbmeta, and keys I extracted from the stock image.

I've also attached the stock vbmeta and custom vbmeta avbtool getinfo outputs. All partitions/keys appear to match, so I'm stuck.

The command I used for creation of the custom vbmeta is:

Code:

python avbtool make_vbmeta_image --key rsa4096_vbmeta.pem --algorithm SHA256_RSA4096 --flag 2 --chain_partition boot:1:keys/boot_key.bin --chain_partition dtbo:6:keys/dtbo_key.bin --chain_partition socko:13:keys/socko_key.bin --chain_partition odmko:14:keys/odmko_key.bin --chain_partition vbmeta_system:2:keys/vmbeta_system_key.bin --chain_partition vbmeta_system_ext:3:keys/vmbeta_system_ext_key.bin --chain_partition vbmeta_vendor:4:keys/vmbeta_vendor_key.bin --chain_partition vbmeta_product:5:keys/vmbeta_product_key.bin --chain_partition l_modem:7:keys/l_modem_key.bin --chain_partition l_ldsp:8:keys/l_ldsp_key.bin --chain_partition l_gdsp:9:keys/l_gdsp_key.bin --chain_partition pm_sys:10:keys/pm_sys_key.bin --chain_partition l_agdsp:11:keys/l_agdsp_key.bin --chain_partition l_cdsp:12:keys/l_cdsp_key.bin --padding_size 20480 --output vbmeta-sign-custom.img

For the flashing process, I'm booting into fastbootd (fastboot reboot fastboot) and then executing fastboot flash vbmeta vbmeta-sign-custom.img. The flash completes fine, but when I try to reboot the tablet (before I've even attempted flashing a magisk-patched boot image), the tablet appears to just switch off after the splash screen. It does eventually reset to the splash screen, but then switches off again for a while and so on. So kind of like a bootloop, but not your typical "fast" reboot cycle.

Any help would be appreciated!

Attached Files

vbmeta-stock.txt
Size: 2.71 KB / Downloads: 58

vbmeta-custom.txt
Size: 2.71 KB / Downloads: 45

vbmeta-sign.img
Size: 1 MB / Downloads: 53

vbmeta-sign-custom.img
Size: 1 MB / Downloads: 60

keys.zip
Size: 23.89 KB / Downloads: 44

jazzk
Enthusiastic Member

9

08-07-2022, 06:09 PM

#2

Hi,

I'm trying to flash a custom vbmeta and magisk-patched boot to my T40 Pro (Unisoc T618). It is Android 11 (so super partition and no separate recovery partition). My bootloader is unlocked.

I've tried creating a custom vbmeta image using the excellent guide here, but the tablet does not boot after I've flashed it.

Attached are the stock vbmeta and my custom vbmeta, and keys I extracted from the stock image.

I've also attached the stock vbmeta and custom vbmeta avbtool getinfo outputs. All partitions/keys appear to match, so I'm stuck.

The command I used for creation of the custom vbmeta is:

Code:

python avbtool make_vbmeta_image --key rsa4096_vbmeta.pem --algorithm SHA256_RSA4096 --flag 2 --chain_partition boot:1:keys/boot_key.bin --chain_partition dtbo:6:keys/dtbo_key.bin --chain_partition socko:13:keys/socko_key.bin --chain_partition odmko:14:keys/odmko_key.bin --chain_partition vbmeta_system:2:keys/vmbeta_system_key.bin --chain_partition vbmeta_system_ext:3:keys/vmbeta_system_ext_key.bin --chain_partition vbmeta_vendor:4:keys/vmbeta_vendor_key.bin --chain_partition vbmeta_product:5:keys/vmbeta_product_key.bin --chain_partition l_modem:7:keys/l_modem_key.bin --chain_partition l_ldsp:8:keys/l_ldsp_key.bin --chain_partition l_gdsp:9:keys/l_gdsp_key.bin --chain_partition pm_sys:10:keys/pm_sys_key.bin --chain_partition l_agdsp:11:keys/l_agdsp_key.bin --chain_partition l_cdsp:12:keys/l_cdsp_key.bin --padding_size 20480 --output vbmeta-sign-custom.img

For the flashing process, I'm booting into fastbootd (fastboot reboot fastboot) and then executing fastboot flash vbmeta vbmeta-sign-custom.img. The flash completes fine, but when I try to reboot the tablet (before I've even attempted flashing a magisk-patched boot image), the tablet appears to just switch off after the splash screen. It does eventually reset to the splash screen, but then switches off again for a while and so on. So kind of like a bootloop, but not your typical "fast" reboot cycle.

Any help would be appreciated!

Gargoyle
Contributor

577

08-07-2022, 08:51 PM

#3

magisk-patched boot must be signed, you can use rsa4096_vbmeta.pem key, then extract rsa4096_vbmeta.pem to .bin and replace boot_key.bin , must be written to vbmeta, don't change --flag 2, leave --flag 0

jazzk
Enthusiastic Member

9

08-07-2022, 08:58 PM

#4

(08-07-2022, 08:51 PM)Gargoyle magisk-patched boot must be signed, you can use rsa4096_vbmeta.pem key, then extract rsa4096_vbmeta.pem to .bin and replace boot_key.bin , must be written to vbmeta, don't change --flag 2, leave --flag 0

Thanks, appreciate the response but the problem is really with my custom vbmeta. I can't get the tablet to boot after flashing that (so haven't even got to magisk-patched boot yet)

hovatek
Administrator

50,891

11-07-2022, 01:15 PM

#5

(08-07-2022, 06:09 PM)jazzk ...
For the flashing process, I'm booting into fastbootd (fastboot reboot fastboot) and then executing fastboot flash vbmeta vbmeta-sign-custom.img. The flash completes fine, but when I try to reboot the tablet (before I've even attempted flashing a magisk-patched boot image), the tablet appears to just switch off after the splash screen. It does eventually reset to the splash screen, but then switches off again for a while and so on. So kind of like a bootloop, but not your typical "fast" reboot cycle.

Any help would be appreciated!

Create a custom-stock vbmeta (same flag as stock, no swapped keys) then flash that and see if the tablets accepts it.
Some models reject any vbmeta with a different flag so you best start with custom stock then make one change at a time
compare your created vbmeta with stock vbmeta using

Code:

python avbtool.py info_image --image vbmeta.img

where vbmeta.img is the vbmeta file name

This post was last modified: 11-07-2022, 01:16 PM by hovatek.

Learn MediaTek, Unisoc / Spreadtrum (SPD) and Qualcomm Software Repairs @ https://www.hovatek.com/training
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gigiline
Enthusiastic Member

5

16-08-2022, 11:41 PM

#6

python avbtool make_vbmeta_image --key rsa4096_vbmeta.pem --algorithm SHA256_RSA4096 --flag 0 --chain_partition boot:1:key/key_boot.bin --chain_partition dtbo:6:key/key_dtbo.bin --chain_partition socko:13:key/key_socko.bin --chain_partition odmko:14:key/key_odmko.bin --chain_partition vbmeta_system:2:key/key_vbmeta_system.bin --chain_partition vbmeta_system_ext:3:key/key_vbmeta_system_ext.bin --chain_partition vbmeta_vendor:4:key/key_vbmeta_vendor.bin --chain_partition vbmeta_product:5:key/key_vbmeta_product.bin --chain_partition l_modem:7:key/key_modem.bin --chain_partition l_ldsp:8:key/key_ldsp.bin --chain_partition l_gdsp:9:key/key_gdsp.bin --chain_partition pm_sys:10:key/key_pm_sys.bin --chain_partition l_agdsp:11:key/key_agdsp.bin --chain_partition l_cdsp:12:key/key_cdsp.bin --padding_size 20480 --output vbmeta-sign-custom.img

Same for me, i have create vbmeta custom (stock img flash without with this command: fastboot flash vbmeta_a vbmeta.img) but with this not flash, is stock on WRITING:, i have see dimension of custom vbmeta and is 20kb, the stock is 1mb, i think the problem is this, any solution?

Gargoyle
Contributor

577

17-08-2022, 04:51 PM

#7

(16-08-2022, 11:41 PM)gigiline ... i have see dimension of custom vbmeta and is 20kb, the stock is 1mb, i think the problem is this, any solution?

python vbmeta_pad.py

gigiline
Enthusiastic Member

5

17-08-2022, 05:53 PM

#8

(17-08-2022, 04:51 PM)Gargoyle
(16-08-2022, 11:41 PM)gigiline ... i have see dimension of custom vbmeta and is 20kb, the stock is 1mb, i think the problem is this, any solution?

python vbmeta_pad.py

now get this error

Attached Files

Immagine 2022-08-17 185332.jpg
Size: 80.33 KB / Downloads: 49

Gargoyle
Contributor

577

18-08-2022, 08:21 AM

#9

(17-08-2022, 05:53 PM)gigiline
(17-08-2022, 04:51 PM)Gargoyle
(16-08-2022, 11:41 PM)gigiline ... i have see dimension of custom vbmeta and is 20kb, the stock is 1mb, i think the problem is this, any solution?

python vbmeta_pad.py

now get this error

Reboot device to fastbootd,
adb reboot fastboot

ganapathid26
Newbie

1

16-09-2022, 06:06 AM

#10

(08-07-2022, 08:58 PM)jazzk
(08-07-2022, 08:51 PM)Gargoyle magisk-patched boot must be signed, you can use rsa4096_vbmeta.pem key, then extract rsa4096_vbmeta.pem to .bin and replace boot_key.bin , must be written to vbmeta, don't change --flag 2, leave --flag 0

Thanks, appreciate the response but the problem is really with my custom vbmeta. I can't get the tablet to boot after flashing that (so haven't even got to magisk-patched boot yet)

I'm also facing same issue after flashing my custom vbmeta. Have you resolved your issue? if yes, please share the details.

Thanks

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