Discussion on question by Roy Hinkley: Fastboot failing with error: FAILED (remote: unknown command)

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07:34

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Q: Fastboot failing with error: FAILED (remote: unknown command)

I am trying to run the following command against a Samsung Galaxy Tab A7 SM-T505 (2020): > fastboot flash vbmeta vbmeta.img target reported max download size of 797411328 bytes sending 'vbmeta' (9 KB)... FAILED (remote: unknown command) finished. total time: 0.016s But as you can see, it fails w...

alecxs

fastboot getvar is-userspace

Robert

AFAIK Samsung devices usually don't provide flashing in fastboot mode. Flashing of Samsung device need to be done via Odin/Heimdall.

Andrew T.

If I'm not mistaken, Fastboot on Samsung devices is only a non-functional stub. Instead, Samsung uses the Download mode.

Roy Hinkley

@Robert - You're both probably right and that Odin is required, but still looking for a way to flash to vbmeta partition.

@AndrewT. Just a matter of determining how to use Odin to perform this task.

@alecxs >fastboot getvar is-userspace is-userspace: no finished. total time: 0.009s

alecxs

that's indeed fastboot (and not recovery fastbootd) guess it's a leftover then they forgot to disable. you can tar boot + vbmeta, patch that tar file with magisk and flash tar file from Odin AP slot

Roy Hinkley

07:34

@alecxs Thank you for the guidance. I will look into your approach.

@alecxs Please see my edit in the post. I don't think I am understanding your instructions. I ran each as separate files boot.tar which worked, and vbmeta.tar which as you can see didn't with no boot image found. Are these files to be combined?

alecxs

both files into one tar file forum.xda-developers.com/data/video/4311/…

Roy Hinkley

@alecxs I am curious about using the AP slot for this flash - after boot, now I'm tripping Knox fuse and geting the Not running Samsung offical software boot window. vbmeta is on its own partition on this tablet. AP partition is for the Android Package, shouldn't it be applied to with BL slot?

alecxs

these slots aren't partitions

topjohnwu.github.io/Magisk/install.html#instructions

Roy Hinkley

@alecxs I have performed all of those items in Magisk instructions. I am now trying to update vbmeta to disable Knox and boot with unofficial ROM. Those instructions say nothing about Knox bypass.

alecxs

I am not sure what you mean with knox bypass. knox is already disabled when you unlocked bootloader. the link describes all partitions belong to the AP slot (you can unpack AP_[device_model_sw_ver].tar.md5 and check vbmeta is in there)

Roy Hinkley

07:34

@alecxs I have added a background section to the post so that you can see the whole picture. Attempting to update vbmeta partition is my effort to disable Knox. If it should be done differently, please provide some guidance. Thank you.

alecxs

I see the Odin log and I see the picture, and it all looks fine. what's your issue, does it not boot?

Roy Hinkley

@alecxs What's my issue? - it's stuck on the Not running Samsung official software boot window. It will stay there until I shut the tablet down or it runs out of power. It's not a very useful tablet in that mode.

alecxs

start from scratch with stock ROM and try again. after step 2, repeat step 1. there is nothing wrong.

Roy Hinkley

@alecxs I have literally repeated the entire process 3 times. Always the same result. Perhaps it's a region issue? I am using BTU. I have tried other CSC regions, but no others work.

alecxs

just to clarify, you have enabled OEM unlocking, unlocked bootloader from download mode, rebooted and finished the initial setup, connected wifi, then enabled OEM unlocking (again) to disable vaultkeeper? okay then I don't know.

Roy Hinkley

07:34

@alecxs As I have illustrated in my post I have done all that, but the last part (step 7) of connect to wifi, enable OEM unlock again, etc. That I cannot do cuz Not running Samsung official software screen prevents any further progress. I don't know how I can explain it any other way. See step 7 for details.

alecxs

In your question and in the tutorial, I read nothing about vaultkeeper (step 3 = repeat step 1) that's why I asked for clarity. sorry about that.

Roy Hinkley

@alecxs No worries, I appreciate your help. I have added screens to illustrate that yes vaultlocker was indeed disabled. I kind of glossed over those details because that part went very smoothly. For the record, the bootloader is unlocked message appears on every boot now. So I am confident that part is all good.

alecxs

08:44

@RoyHinkley with which options you have patched the AP_[device_model_sw_ver].tar.md5

alecxs

09:06

@RoyHinkley I have an idea you can try. first, extract all the files from the stock ROM with 7zip, extract the vbmeta_samsung.img (with LZ4), rename it vbmeta.img, and put together with (extracted) boot.img in tar archive. Let magisk patch it, make sure to disable the vbmeta checkbox. then extract the magisk_patched.tar and rename the patched file back to vbmeta_samsung.img. repeat this for the real vbmeta.img, now you have three patched files boot.img, vbmeta.img, vbmeta_samsung.img.

pack these files back into stock ROM, flash the whole ROM together with BL AP CP CSC.

Roy Hinkley

14:31

I am kind of stuck now. Ever since I used Odin to flash the boot and vbmeta images, I cannot get Odin to reinstall anything now, nor can I install any apks. So, at the moment, the tablet is kind of bricked, but not totally, perhaps recoverable.

Okay, was able to flash back to stock ROM. Question on the extract the vbmeta_samsung.img (with LZ4), rename it vbmeta.img - I have already extracted all of the stock rom files from before, and there are 2 vbmeta.lz4 files --> vbmeta.lz4 and vbmeta_samsung.lz4. Is this considered in your suggestion?

Correction on the names of the files, the extracted files referenced are vbmeta.img.lz4 and vbmeta_samsung.img.lz4

alecxs

15:09

@RoyHinkley yes, my suggestion is, let magisk patch vbmeta_samsung.img as it were vbmeta.img, because I am not sure vbmeta_samsung.img is handled by magisk at all

Roy Hinkley

18:01

Okay, I performed the following:
1 - copy vbmeta_samsung.img.lz4 and rename vbmeta.img.lz4 replacing original vbmeta.img.lz4
2 - archive extracted ROM files including replaced vbmeta.img.lz4 into new tar file
3 - push tar to tablet
4 - Use Magisk to patch the tar file
magisk failed:
- Device platform: arm64-v8a
- Installing: 25.2 (25200)
- Processing tar file
-- Copying: Users/Me/Documents/Android_OS_Imaging/temp/taba7-image/
-- Copying: Users/Me/Documents/Android_OS_Imaging/temp/taba7-image/boot.img.1z4

@alecxs The tar contains a boot.img.lz4, so I am unsure why it's complaining about it missing.

alecxs

18:23

@RoyHinkley you must unpack the three files with LZ4 first (boot vbmeta vbmeta_samsung). only patch the three files. this is done on two steps as you can only patch one vbmeta.img at time. when done, unpack the tar files, rename the vbmeta.img back to vbmeta_samsung.img then repack the images with LZ4. now you have to replace three files in stock AP.tar

alecxs

19:09

...

<ID:0/007> vbmeta.img

<ID:0/007> blgrd.mbn

<ID:0/007> grd_fw.img

<ID:0/007> vaultkeeper.mbn

<ID:0/007> recovery.img

<ID:0/007> dtbo.img

<ID:0/007> super.img

<ID:0/007> userdata.img

<ID:0/007> metadata.img

<ID:0/007> vbmeta.img

<ID:0/007> vbmeta_samsung.img

...

alecxs

19:36

it seems vbmeta is flashed two times. hopefully the patched one is flashed last?

Roy Hinkley

20:49

@alecxs I just want to make sure I understand the directive.
1 - Use lz4 to extract boot.img.lz4, vbmeta_samsung.img.lz4
2 - make copy of extracted vbmeta_samsung.img and rename it to vbmeta.img
3 - tar boot.img vbmeta.img together into 1 file.
4 - tar boot.img vbmeta_samsung.img together into 1 file.
5 - push both tar files to tablet
6 - use Magisk to patch each file
7 - pull patched files from tablet
8 - Use Odin to flash each patched file using the AP slot

Do I understand correctly?

@alecxs Forgot to ask, is there an order to which you see these files should be flashed?

alecxs

21:51

@RoyHinkley yes, but 3. and 4. should contain identical file names (for different files)

vbmeta.img + boot.img = vbmeta.tar

vbmeta_samsung.img -> vbmeta.img + boot.img = vbmeta_samsung.tar

Roy Hinkley

22:05

@alecxs Roger that. How about flashing order? Assuming vbmeta_patch then samsung_patch - not filenames just conceptual.

alecxs

after patching both tar files like in the video, extract both tar files and rename the incognito vbmeta.img back to vbmeta_samsung.img (that one from formerly vbmeta_samsung.tar, don't mix up these two)

You have three patched files now. pack all three files together into one tar for flashing. there is no order to keep as each file has back its own name.

boot.img + vbmeta.img + vbmeta_samsung.img = patched.tar

Roy Hinkley

22:26

@alecxs Magisk cannot process either file

magisk failed:
- Device platform: arm64-v8a
- Installing: 25.2 (25200)
- Processing tar file
- Copying: PaxHeader/boot.img
- Copying: GNUSparseFile.O/boot.img Patching: vbmeta.img
-- Writing: vbmeta.img ! No boot image found
! No boot image found
! Process error
! Installation failed

Hey I really do appreciate your help on this. But I have some administrative duties to take care of and will not be working on this over the weekend. I will likely pick back up on Monday. Again, thanks for your help. :)

alecxs

22:52

@RoyHinkley seems you have used some incompatible GNU tar options. try with busybox tar.

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