yashsingh1/xdaforums huggingface dataset:
[Android General] MotoJunkie01:
It does sound bricked. If you could achieve adb/fastboot communication with your PC, as you know, your device could likely be saved. Here is a link for the TB3-850F Stock Boot & Recovery Images. Also, I have included a copy of the Official Lenovo USB Drivers for the TB3-850F. It is the most current release, v1.21. Install this driver package on your PC. With your device powered off, try holding Volume + for 5 seconds and, while continuing to hold, insert the micro USB to your device from your PC connection. This will sometimes force adb/fastboot communication between your tablet and your PC. Should you succeed there, try flashing the stock recovery and/or boot images in the link via fastboot mode.

https://drive.google.com/folderview?id=0B7-zQU1VihD3T1Z4MzBjT2FhcGc
[Android General] kellogg9662:
I followed your suggestions and got it to boot into adb and then got it into fastboot. I flashed the stock boot and recovery but that didn't fix it. I found your stock system img in another thread and flashed that and then everything booted up ok. Thanks for the help!
[Android General] MotoJunkie01:
Very glad it worked out for you. Another Lenovo Tablet saved!! Sounds like your issue was with the /system partition. Out of curiosity, what method did you use to get adb working, and which method did you use to flash the /system image. ?
[Android General] kellogg9662:
Yeah, I'm not sure how I screwed it up but I'm glad it's working. In order to get into adb I tried the method you mentioned of holding the volume+ for 5 seconds and then plugging in the usb cable. From there I used adb to reboot into the bootloader. I tried flashing the boot and recovery images from there, but it didn't seem like they took. So then I used the fastboot boot command with the TWRP image, but it wouldn't let me access the data partition for some reason. I went to reboot and then all hell broke loose and it was just rebooting through TWRP failing with openscript and then rebooting again nonstop. I couldn't manage to shut it off completely even holding the power button for 30 seconds or so. I figured I was screwed, but held the volume up, volume down (and I think power?) at the same time and suddenly it actually launched TWRP. However, it couldn't access the data partition for some reason. I threw the stock boot, recovery, and system images on an SD card and then flashed them all and that finally got it working.

I've rooted other phones, but I've had hardly any experience with adb. Fortunately I feel like I did learn quite a bit from screwing up, which is always a plus.
[Android General] MotoJunkie01:
Great work. Sounds like a good learning experience for you also. These devices on a MediaTek platform are a horse of a different color indeed. I've bricked a good handful of these devices through trial & error myself. By the way, please be sure and hit the thanks button on the OP. [MENTION=6939319]Hemphiz[/MENTION] done an excellent job initiating TWRP & root for this great budget tablet.

I am currently working on a stock based 6.0.1 ROM for this device: rooted, deodexed, debloated & zip aligned. I'll add a few baked-in features like Substratum & Viper4Android. Also I'll add a couple of tunable governors & tweaks to the stock kernel. I'm terribly tied up at work, resulting in having to take a couple weeks break from Android, but I should be up & running again in 3 weeks or so.

Anyway, I'm very glad it worked out for you. Try this to iron out any bugs with booting TWRP. First, save a copy of the twrp.img to your internal storage or external micro SD card. Next, get your device into TWRP. Select INSTALL, then select the flash img option in the bottom right-hand corner. Navigate to the location of your TWRP.img, commence to install and select "RECOVERY" when prompted to do do. Once done, wipe Cache & Dalvik/ART. Reboot system. This should allow smooth booting of TWRP, with no loops or lags.
[Android General] somebody100:
i successfully rooted my lenovo tablet

thank you very much
[Android General] pndwal:
Very interesting. You've now overtaken my knowledge of boot.img. - I assumed the two would be the same. Does boot.img contain items other than kernel and ram-disk? Or are these simply packaged differently, with identifiers that only work with a specific ROM (eg. LOS)? PW.

---------- Post added at 07:49 AM ---------- Previous post was at 07:30 AM ----------

Could you post modified boot.img here for us? And, with your permission and credit to you, may I post it on Russian 4PDA Tab3_8 thread so others (including those who already tried LOS14.1 ROM on TB3-850F) can flash and trial this?

Many thanks for your skilful efforts. PW.
[Android General] wezroot2k:
Yes i will post the modified boot.img for sure and go ahead and Post on Russian 4pda. Anything that can help get us a proper lineage 14.1 port for the 850F. So just go ahead and do what you must.:good:
[Android General] wezroot2k:
re TAB3-850F -mod_boot.img

OK PW here's the boot.img and could you just give a big shout and thank you al_rus for is tremendous work on the 850m LOS 14.1 ROM:good:
[Android General] wezroot2k:
OK people so i tried to do some porting last night and it was a no go, there was no error in flashing ROM but it boot-looped and by that i mean it did not to boot to OS but it did not freeze or restart but just would not past the boot animation screen was on the screen for a while I try to wipe dalvik and cache and it still would not past boot animation screen so I'm gonna try again from scratch and see if i can get it to boot OK.

PS: PW seems like you and I are on the same wavelength in terms of posting the mod 850f boot.img i was considering talking to you about doing same thing until i saw your post and i am very happy that i could post it for everyone.

Thanks man

---------- Post added at 05:20 PM ---------- Previous post was at 05:00 PM ----------

Yes they do. when i extracted it the file were as follows: initrd folder, bootinfo.txt, cpiolist.txt a boot-old.img,kernel .zip and ramdisk.zip.

here's the info from the boot info text file

base:0x40078000

ramdisk_addr:0x44000000

second_addr:0x40f78000

tags_addr:0x4e000000

page_size:0x800

name:1472186745

cmdline:bootopt=64S3,32N2,64N2 androidboot.selinux=permissive buildvariant=userdebug

padding_size:0x800

the above info in is from the modded boot.img

also the initrd folder there is file ueventd.rc that when porting will help with boot-loops.
[Android General] pndwal:
What porting changes resulted in bootloop?

Many thanks for your continued efforts with this, and for your comprehensive answers and keeping us up to speed! Hope you keep on with porting efforts. :) PW

And thankyou too

I'll post it today.

Thanks for this info.

Is LOS booting with SELinux=permissive??? This is concerning - its enforcing in stock. PW

---------- Post added at 09:24 PM ---------- Previous post was at 09:21 PM ----------

Thanks, and sure, yes, I'll post and thank al_rus today. PW
[Android General] wezroot2k:
could you explain why is this concerning? but i can confirm this, in the settings of the device about emulated device under phone status it says SElinux status Permissive.
[Android General] pndwal:
It has serious security implications, and can cause saftey-net check, and I think Magisk hide to fail (can't use android pay, etc). Many apps got around security in past using permissive, but Google made enforcing mandatory to close security gaps / protect from malicious code, and most Devs have now made their apps and mods run in enforcing SELinux environment (it was largely root permitted apps that previously took advantage of the same security gaps to work, with permissive set) - for example, I once needed permissive to run Viper Audio (with Neon and ARISE), but these have now been fixed to work with enforcing. Further, many apps (banking etc) now require enforcing to work.

I think permissive environment can be easily changed to enforcing with SELinux Toggler and other root apps, but proper kernel setting would be more ideal. PW
[Android General] wezroot2k:
well nothing i could pinpoint right off the bat build during the porting process all did was to replace certain folder eg: xbin etc and so fourth so i can't say if it is a particular file or folder or lack thereof. but it not first this as happen before in terms of not booting to OS.

PW remember when you suggested i test stock 850f build.prop functionality with the 850m boot.img the exact same boot-loop happened just stayed on boot animation screen and not booting to OS. So my hunch is that that while porting

the build.prop needs to bee edited and ported also.

what do you guys think?
[Android General] pndwal:
I think so too. I read somewhere re boot.img containing build.prop info which may account for failure with 850f one, so seems build.prop entries are often critical. PW
[Android General] pndwal:
Posted TB3850F_MOD_boot.zip and thanks to al_rus at Russian 4PDA site http://4pda.ru/forum/index.php?showtopic=764969 post #1202 and #1204. Google translate to Russian just adequate.

Big shout and thank you [MENTION=8548258]wezroot2k[/MENTION] for tremendous work on the TB3-850F LOS 14.1 ROM too. :good: PW
[Android General] wezroot2k:
just view the post over Russian 4PDA just wanna says thanks again and will continue to do anything to help with this port.

also i gonna try and do some porting and tests over the next couples of days and keep you guys posted

okay:good:
[Android General] pndwal:
News Flash for users of TB3-850F!

We now have stable LOS14.1 for TB3-850F! :)

Simply flash TB3-850M LOS 14.1 ROM from [MENTION=5968730]al_rus[/MENTION] of Russian 4PDA, then flash TB3850F_MOD_boot.img from zip file from [MENTION=8548258]wezroot2k[/MENTION] (of XDA) to cure bootloops and instability on TB3-850F.Enjoy!

Reading: Details of efforts with this on the last two pages here.

Files:

TB3-850M LOS 14.1 ROM: https://yadi.sk/d/FKiFjn9x3Rp4MU

TB3850F_MOD_boot.zip: https://xdaforums.com/attachment.php?attachmentid=4698911&d=1549212166

A big Thank You to [MENTION=5968730]al_rus[/MENTION] (4PDA, TB3-850M firmware thread, http://4pda.ru/forum/index.php?showtopic=764969) for his tremendous work on TB3-850M LOS 14.1 ROM.

Also, Kudos to [MENTION=8548258]wezroot2k[/MENTION] (upcoming XDA developer) for TB3850F_MOD_boot.img (kernel and ramdisk port) and for continuing to make adjustments to LOS14.1 to streamline it for TB3-850F. :) PW

- Similar message (without file links) posted in following XDA TB3-850F threads:

- https://xdaforums.com/android/help/lenovo-tab-3-8-tb3-850f-unbrick-root-t3598727

- https://xdaforums.com/android/general/rom-lenovo-tab-3-8-tb3-850f-t3617594

- https://xdaforums.com/android/help/qa-lenovo-tab-3-8-tb3-850f-t3700868

- https://xdaforums.com/thinkpad-tablet/development/rom-stock-android-6-0-rom-lenovo-tab-3-t3825165

- https://xdaforums.com/android/general/rom-lenovo-tab-3-8-tb3-850f-android-6-0-t3593043

- https://xdaforums.com/android/help/lenovo-tab3-8-2016-custom-recovery-t3483454
[Android General] pndwal:
News Flash for users of TB3-850F!

We now have stable LOS14.1 for TB3-850F! :)

See post above. Regards, PW.

Alerting:

[MENTION=6939319]Hemphiz[/MENTION]

[MENTION=5273366]Lister Of Smeg[/MENTION]

[MENTION=1662557]mtpc[/MENTION]

[MENTION=5003632]stonedpsycho[/MENTION]

[MENTION=1533335]fran89[/MENTION]

[MENTION=8243079]r&xp[/MENTION]

[MENTION=5366561]john3voltas[/MENTION]

[MENTION=9503475]Garcy23[/MENTION]

[MENTION=6379827]voland34[/MENTION]

[MENTION=7942469]DeblaGaming[/MENTION]

[MENTION=3886927]sorun343[/MENTION]

[MENTION=5522475]limited_imagination[/MENTION]
[Android General] TheAppSwitch:
Thanks for this, imma try it for now
[Android General] voland34:
Stuck! help is appreciated

Hi. Happy to hear this finally. So i just went ahead, did full wipe and installed LOS rom plus afterwards MOD_boot.img. Then rebooted, it went fine but setup wizrd keeps crashing after entering Wifi settings, it says the setup app cant start, and gets me in a loop. only options are power off and restart (but keeps on smae process ending in setup loop). I cant get it to go twrp with button combo (i remember it was tricky), so i'm stuck at this point in this loop...any help?

Update: i skipped wifi setup and it moved ahead.

So priblem solved. It seems fine so far.
[Android General] wezroot2k:
Ok voland34 and PW here's the thing sorry for not mentioning about the setup crashing because of the wifi setup, but i did not expect people to be testing so soon but i am happy to know this.

Voland34 and PW it just a minor bug that does not make this LOS port unstable what so ever or unbootable so don't worry.

The solution is simple and want everybody to read this, all that needs to done especially for Voland34 is he need to go to the wifi settings and forget the network he is connected to and then continue setup by skipping the options when it boots to the OS then you can go ahead and connect back to the your wifi network:good::good:

For everyone else considering installing this LOS port just remember do not try to connect to wifi during the initial setup but you must boot to the OS first then connect to the WIFI.

Thank you all.:good::good::good:

---------- Post added at 02:34 PM ---------- Previous post was at 02:32 PM ----------

I"m gonna try and see what causes the WIFI to crash during initial setup and keep you guys posted
[Android General] pndwal:
Good to hear this.

[MENTION=8548258]wezroot2k[/MENTION] has it running "flawlessly" (meaning its stable but will have bugs), but I'm yet to flash. Just getting the word out.

See my post #66 in [MENTION=5273366]Lister Of Smeg[/MENTION]'s thread: https://xdaforums.com/android/help/lenovo-tab3-8-2016-custom-recovery-t3483454 for instructions including TWRP button combo.

Posts #69 & 71 are useful too.

Regards, PW.
[Android General] voland34:
Yes, i managed to figured that out, so now it works great so far. I cant seem to get spanish evnen if i change language (only russian and english) but i can live with that.

Another question i have is if though its a rooted rom, it might be interesting to flash magisk 18.0 ...any idea? Its just about flashing magisk at twrp or that might be wrong and better leave it alone?

Thanks a lot
[Android General] wezroot2k:
Hey Voland34 about booting Twrp with the buttons i know it kinda tricky

My suggestion though is that don't try to press the buttons all at once but try and press the vol up and down button together after the after the short vibration and logo screen or better when it boots to the boot animations press the power until it power down and immediately press vol up and down button at the same only letting go quckly after logo appears:good:

hope this helps every one:good:
[Android General] pndwal:
Close, but not quite. See my post above :) PW

---------- Post added at 03:54 PM ---------- Previous post was at 03:48 PM ----------

I'd try flashing Magisk from TWRP. I've flashed this over prerooted custom ROM on my Huawei Y550 phone with no problems. Magisk generally handles any cleanup well, and has now overtaken the functionality of SuperSU. PW
[Android General] wezroot2k:
OK PW see what you mean gonna try it right away:good:

maybe you need re-post it here.:good:

BTW PW Thanks you for sending the word outabout LOS port for me i've seen the posts and i even got a PM inbox so thanks again

---------- Post added at 03:31 PM ---------- Previous post was at 02:59 PM ----------

yes its a rooted ROM comes with a su addon that ca be activated in developer options, but you can go ahead try Magisk 18.0 or Chainfire Super SU.

the first time i flashed LOS 14.1 rom i had flashed magisk 18.0 with no problems or conflicts but i do remember magisk

havingan error at the google security check option i think.
[Android General] voland34:
Done: opengapps pico + magisk 18.0, so far so good.

By the way: titanium BU not qorking correctly.
[Android General] wezroot2k:
how do mean not working correctly?

just DL it from Playstore it only crashed once and reopened it booted up and displayed a message about SU and suggesting i install chainfire su or magisks.
[Android General] voland34:
It installs and gets open but doesnt restore user apps, only data. It hasnt happened to me ever before...
[Android General] pndwal:
In developer options in LOS14.1, do you have "advanced restart" to reboot to recovery, bootloader, soft reboot? (I'm still on stock).

You can reboot to recovery, bootloader or soft reboot from kernel adiutor too: select Recovery, select TWRP, hit circular icon.

Also, I edited info "To Enter TWRP":

After powering down wait at least 5 seconds after vibration, then press power, wait between 0.5 & 1 sec, then hold both vol up & down also (all 3 buttons) until vibrates. This timing is critical, bit will boot to TWRP every time once you get it right.

PW
[Android General] wezroot2k:
Yes PW there is an "advanced restart" in developer options
[Android General] limited_imagination:
Awesome work guys, congratulations.

I had not been following this thread for a while, after running into multiple roadblocks in trying to build an 850f kernel from source. I have kind of given up that project for the moment, but perhaps inspiration will strike again...

Reading the last couple of pages of this thread, it looks like the way you have got LOS 14.1 working, is by replacing the kernel of the LOS 14.1 850m port with the stock kernel of the 850f.

My own peculiar interest is to make it possible to load serial port drivers (or other device drivers), that were not included in the stock kernel.

I was able to compile a loadable kernel module of the FTDI serial port driver for the 850f, but the stock kernel of the 850f does not appear to be configured to allow an LKM to be used.

So it looked to me like an entirely new kernel would have to be compiled from source code to add any new device drivers, which would have to be loaded during the boot process . And if I had been successful in doing that, I would have configured the kernel to allow any subsequent LKM as well.

So correct me if I am wrong, but I suspect that even though you have LOS 14.1 running on the 850f, you still would not be able to add any device drivers that were not originally configured in the stock kernel.

Or are there bells and whistles in LOS 14.1 that would let you load new device drivers, irrespective of using the stock 850f kernel? That would be FANTASTIC if so!
[Android General] wezroot2k:
ok LI here's the thing i cannot give a definite answer in-terms of the drivers but i can give you an idea interms of what the structure of the files in the boot.img (where the kernel is) when i extracted the boot.img there was this folder called initrd which also contain folders of which majority of which was empty except for sbin folder which contained two files adbd and healthd so all did was just copy the kernel and ramdisk files from 850f to 850m boot.img but i think there is room within LOS for other device drivers remember this LOS 14.1 is not a hugh ROM so maybe with a little work we could get a full custom for the 850F with some improvements to kernel worth a try. if you want i could send you PM with the folder of the extracted boot rom for you to examine.

thank you
[Android General] pndwal:
Yeah, this would be a bit over my head, but hope you get help with it. PW.
[Android General] AeonFlux1603:
I am by no means an expert on this type of thing, but from what I'm reading, and in following your amazing efforts, I believe you would benefit from researching possible utilization of the FIsH Hijack exploit for Android which, among other things, will allow you to boot a custom ROM (even a ROM of a higher version) using simply the stock boot image. This exploit was used by the Russian developers on their port of LOS 14.1 and Resurrection Remix (Android 7.1.2) to the TB3-850M variant of the Tab 3.
[Android General] wezroot2k:
thanks for that info didn't know about Flsh Hijack exploit mightbe just what we are looking for.

do have a link?
[Android General] pndwal:
Our OP-gone-AWOL mentioned he was using this in the LOS port he produced but never published. He said:

https://xdaforums.com/thinkpad-tabl...k-android-6-0-rom-lenovo-tab-3-t3825165/page3 post#24. See also post #257 this thread.

I never heard any more about it. PW
[Android General] AeonFlux1603:
I'm fairly certain it will be possible for you to boot LOS 14.1 using the stock Linux 3.18.19 boot image for the current build of stock Android 6.0. [MENTION=7550078]pndwal[/MENTION] posted the exact links I was looking for. Thanks [MENTION=7550078]pndwal[/MENTION]; I'm in hopes that FIsH will be beneficial here. Another advantage of FIsH is that all your requisite hardware blobs and drivers stay in place.
[Android General] AeonFlux1603:
I'm hearing over at Android Central that the Russian Devs have a functional LOS 14.1 for the 850F. It is also reported that the original OP for this thread built a stable LOS 14.1 for 850F, but it was never posted on XDA. I'm jumping through hoops trying to locate a download link for an 850F Nougat ROM, but I can't seem to find anyone willing to share a source. It's pretty well certain that a Nougat build exists for this device, but finding it is proving to be tumultuous to say the least.

If one of you guys can give me a link for the base LOS 14.1 for the 850M, I'll give it the old college try with the FIsH Hijack exploit. I've decompiled the stock Linux 3.18.19 boot image for the 850F (on the most recent 6.0 build), and I have a FIsH porting guide for a Nougat based build. I can try but again, you guys are the experts. I can try however.

Update. Ok I feel really dumb now. It looks like you guys already have a working LOS 14.1. Am I correct that flashing the 850M LOS 14.1 with the patched mod boot image will boot the 14.1 ROM on 850F?

It seems I'm guilty of being a Noob in the 1st Degree, punishable by public ridicule and a swift kick in the ass. But, to be clear, now that you guys have a working LOS 14.1, what is it exactly that you're stuck on now? I've missed something (because I'm a Noob).
[Android General] pndwal:
Ha ha ha :) - don't beat yourself up over it - your advice is helpful and valuable!

The base ROM is the very same as [MENTION=7383447]MotoJunkie01[/MENTION] successfully ported, and [MENTION=8548258]wezroot2k[/MENTION] successfully patched for TB3-850F. Its TB3-850M from 4PDA. Link: post 697 http://4pda.ru/forum/index.php?showtopic=764969

About firmware:

1. This is a port with ARK-Impulse-P2, created by chipa76

2. In the firmware all the basic functions work

3. Route is built-in, turn on the menu "For developers"

4. Kernel and communication module from the latest at the moment the 36th firmware.(stock M)

[MENTION=7383447]MotoJunkie01[/MENTION] while offering untold support and help to members over several years, especially in his 35 or so threads, basically spat the dummy, took offence and abused members here. Each time the threads were cleaned by mods, but were full of colourful language. The last time he swore not to release LOS port though complete (Posts 339, 341) because of one member, and account was shut down swiftly anyway.

[MENTION=8548258]wezroot2k[/MENTION] has taken up the baton and succeeded with kernel and ramdisk port to 850F for us, unlike [MENTION=7383447]MotoJunkie01[/MENTION]who rebuilt kernel for 850F, and used FiSH in port. I've searched for it too, but seems [MENTION=7383447]MotoJunkie01[/MENTION] has been true to his word and hasn't posted it despite stringing us along for so long, so expect you won't find link, but you have 850M one above.

Android Central reports that the Russian Devs have a functional LOS 14.1 for the 850F may refer to [MENTION=8548258]wezroot2k[/MENTION]'s efforts which I posted on 4PDA, or may really be regarding 850M.

[MENTION=8548258]wezroot2k[/MENTION] continues to debug and can use any help. Thanks & regards, PW.