yashsingh1/xdaforums huggingface dataset:
[Android General] pndwal:
No worries. Sorry if I upset you, I don't want to argue either, I just like clear, factual information and it's all a bit too contradictory for me.... Better keep your feet up for a while, and I'll get on with other things too. All best, PW.
[Android General] pndwal:
I found info on Mediatek chip Suffix convevtion I'll post for anyone interested - (From a Chinese Mediatek promotional article):

"T is enhanced version, [some say for 'turbo', but there isn't an MT6735T I know of], generally based on the standard version of the CPU to enhance the frequency or GPU frequency,

M is for the low frequency version, the same way, reduce the frequency of CPU or GPU.

P (this is not common) is the overall specification for castration, even weaker than the M version of the chicken." Chuckle. PW
[Android General] MotoJunkie01:
The "M" suffix is commonly referred to by OEMs and developers alike as "modem," since the mt6735m is in fact a comm-ready smartphone chipset (rarely ever used in tablets, WiFi only or otherwise). Although significantly underclocked in contrast to the base mt6735, it is no cheaper in price, perhaps because it ships with all needed comms, sockets and slots -- a full and true SoC, comparable spec-wise and by benchmarks to Qualcomm's Snapdragon 410 (msm8916).

Ironically, the LOS 14.1 ROM I have been porting to the 850F is based from a LAVA Iris smartphone with the mt6735t, a device which is considered a complete disaster by the unfortunate folks who bought it. The mt6735t has a reputation of thermal distress during instances of heavy core load and kernel panic. This is likely the very reason the mt6735t isn't used by many OEMs as a board platform.
[Android General] MotoJunkie01:
On a thread topic note, I've been as guilty as anybody for the rather lengthy colloquy of off topic material. I'll now work to veer this thread back to the topics of bootloader, TWRP & root related subject matter. This device does need a dedicated thread for Q & A and spec related topics. Moreover, and I will need to run this idea by a moderator to get a clear answer, but it does appear that the Lenovo Tab 3 8 has a dedicated device forum -- the Lenovo Thinkpad forums. While our device doesn't necessarily fit within that particular category technically speaking, our device does have threads posted within that forum, along with threads for the Tab 3 8 Plus, the Tab 4, Tab 4 Plus, etc. So I'll try and get an answer on this.
[Android General] MotoJunkie01:
[MENTION=7550078]pndwal[/MENTION] this week coming will be my busiest for work, but hopefully my last week out on overtime and away from home. I will have little time to check in on the threads, and I will be much obliged to you if you can assist members with their questions and issues in my abscence. Hopefully I'll be closer to home this time next week. Thanks as always for your dedication and assistance.
[Android General] pndwal:
No Problem.

Watch those 15 hour days don't kill you! - PW
[Android General] MotoJunkie01:
Thank you friend. Talk to you soon.
[Android General] comfortable:
Has anyone successfully added USB Mass Storage mode as an option to this tablet when hooking it up to PC? I simply cannot live with MTP and am amazed anyone can.
[Android General] RenaKunisaki:
I think most people deal with it by using ADB push/pull or removing the SD card and plugging that into the PC.
[Android General] MotoJunkie01:
Yes. USB Mass Storage is extremely unreliable and results in data corruption and data loss quite regularly. I've seen some real horror stories of data loss due to USB Mass Storage. This is exactly why the feature is no longer included in Android open source code and why MTP has taken its place.
[Android General] pndwal:
Actually, this tablet has it (stock). Called USB Storage. I can simply plug device into my set top box, and USB Storage option comes up (with note win XP is recommended) allowing STB to play MP4 files as it will from a USB stick, and record to SD in device too. (Not sure why you can't see it). Of course, it won't work if SD is formatted adoptive (F2FS and encrypted). I think FAT is required.

As has been noted, old bulk storage ability is no longer officially supported in android OS. (This happened due to problems when phone looses access to whole SD in this mode - phone retains access in mtp mode.) However, most Lenovo devices (up to M anyway) seem to have it enabled still.

On devices without out-of-the-box support, it can usually be enabled using Universal USB Mass Storage enabler, here:

https://xdaforums.com/android/apps-games/app-universal-mass-storage-enabler-beta-t3240097

This requires SELinux set permissive, but it takes care of this itself after requesting permission. However, you should already have mass storage (with enforcing SELinux) out-of-the-box as I mentioned. PW.
[Android General] MotoJunkie01:
This device certainly does have USB Mass Storage, and it's not part of the Android 6.0 open source code, but rather a specific feature added by Lenovo to this device (and most Lenovo tablets running Android 5.1 and later). In other words, vanilla Android 6.0 does not have a USB Mass Storage option. It was deprecated sometime around Android 4.4.2 KitKat. Here's a detailed discussion on Reddit as to why USB Mass Storage was a horrible idea with the Android OS. https://amp-reddit-com.cdn.ampproje...y_do_new_versions_of_android_not_support_usb/

There are confirmed cases (in the extreme) where the /userdata partition of an Android device became completely destroyed (corrupt filesystem) due to the way Windows mounted the partition (and failed to properly unmount during filesystem handover). I would urge any Android user to never use the USB Mass Storage protocol (or the synonymous"USB Storage" on our device), but rather the much improved and infinitely safer MTP or PTP protocols. [MENTION=7550078]pndwal[/MENTION] I'm sure you have probably seen too, firsthand, the negative issues of the older storage protocols.
[Android General] comfortable:
Edit: so it turns out I got the model number incorrect! I have the 8703F. Sorry guys. It's been a while since I used it precisely because of the MTP-only nature of the tablet

----

Deleted most of post.

Summary:

Always found MTP to be unreliable (files not showing up, slower file transfers, less compatibility) and USB Mass Storage reliable and flexible (any app can write to a real drive letter and I can connect 2 tablets together with an OTG cable and enable Mass Storage mode to share files fast without a brain-frying wifi app filled with analytics). And so on. Haven't had a corruption issue despite years of weekly usage on multiple devices.
[Android General] pndwal:
But this is also MTK processor.

What is your firmware revision? Mine is TB3-850F_S100031_171010_ROW.

Are you sure SD is formatted as portable? Have you tried another SD freshly formatted?

Some files not showing up with mt protocol is because, as I mentioned, phone retains access to filesystem in mtp mode, and may not have handed off access to that file as a phone app or phone system is still accessing it. This solves problems when phone looses access to whole SD in mass storage mode, but can be annoying figuring out why a particular file or folder is not showing.

Like you, I used mass storage for years without problems, but an understanding of the differences in transfer protocols allows you to see the potential problems with mass storage. Probably most disastrous problems occur with PC connection. Windows often detects problems with a 'drive' when there aren't any and may offer to scan and fix for example, and I've seen this corrupt mass storage, so you can appreciate concerns many (like [MENTION=7383447]MotoJunkie01[/MENTION]) have regarding mass / bulk storage. And these problems are eliminated with the selective hand off of access used by MTP (which has the added benefit of still being able to display internal user data partition despite being formatted in faster Ext4 / F2FS etc, as well as SD cards formatted with F2FS, Ie adoptive). PW

---------- Post added at 01:56 AM ---------- Previous post was at 01:53 AM ----------

Well there you go! Hope you find a solution for that device also.

Regarding UMS enabler, the OP said:

My guess is that the absence of kernel support is why it's not working for you.

All the best, PW
[Android General] comfortable:
Thank you for the detailed reply, pndwal. I wish Android models were more consistent. Some have this, some don't, etc. Often you don't know until you buy it. Despite some advantages, MTP still doesn't add up for me because of its disadvantages, so I hope I find a solution.

Thanks again.
[Android General] pndwal:
No worries.

Seems Android policy itself is pretty consistent - only MTP support since 4.x. But OEMs like Lenovo seem to have resisted the change. Perhaps they see the benefits of supporting mass storage as you do, and kept it alive at least in K, L & M. - (Although this may only be on MediaTek devices as you noted.)

With the new adoptive formatting ability (most with low end speced devices really appreciate this), MTP transfer is just plumb necessary, so my personal feeling is that MTP adoption as an across the board solution is a good decision.

Please let us know if you find a solution, but sounds like you may need to find or wait for a custom ROM / kernel for your device with kernel support to make it work. Many have faced the same issues, and have reluctantly admitted defeat and adopted alternative methods.

Bit more on why Google did it:

Happy hunting :) PW
[Android General] MotoJunkie01:
Great points. The big corporate apple does play a huge part due to filesystem patents.
[Android General] pndwal:
Yeah - read somewhere it was about $5 per device for OEM, I assume for using FAT internally. (I'm guessing they wouldn't have a levy just to allow FAT SD use, but who knows...) PW
[Android General] MotoJunkie01:
Yeah I've read the same figure of about $5 per device, so that's probably accurate (it is also reported that Microsoft allowed manufacturers of various mobile electronics to use FAT at 25¢ per royalty, with a cap of $250,000). I've wondered the same thing as you -- why is FAT/ FAT32 not a micro SD filesystem standard by patent or levy underwritten by Microsoft? I'm sure it would have been a lucrative move. On eMMC protocols, I'm partial to an EXT4 system partition and F2FS userdata partition, like Motorola Mobility uses on many of its smartphones. But, on the downside, that combination has created a huge issue known as the loopback bug. Magisk offers a module as a workaround until Motorola fixes the bug by way of kernel commits. (Ironically, in 2010, Microsoft filed suit against Motorola Mobility over alleged infringement regarding the FAT filesystem protocol). VFAT, also patented by Microsoft, is extremely popular within the Android GPT, and writers of Android source code have implemented a type of coding to somehow circumvent adherence to copyright laws in using VFAT on eMMC storage.

Anyway I'm rambling and thinking out loud. I'm coming home Tuesday by the way [MENTION=7550078]pndwal[/MENTION]. I'm eager to jump back in where I left off.
[Android General] pndwal:
Could be off topic, but since you don't seem to mind: seems most LOS iterations use EXT4 system partition and F2FS userdata and cache partitions also. I assumed there was just some difficulty with F2FS system. What's loopback issue? PW
[Android General] MotoJunkie01:
In a nutshell, kernels on Android devices which have a F2FS formatted /userdata partition have an inherent bug that prevents loopback devices (.img files) from being mounted as R/W. With systemless root on.such devices, a huge problem ensues (Magisk systemless root relies on a magisk.img scheme). So, as a workaround, the patch moves magisk.img to the /cache partition (EXT4) and linking it to its actual location, /data/adb/magisk.img. The patch fix also recreates magisk_merge.img upon every reboot and utilizes it exactly like it would magisk.img.

This is the only way most Motorola devices can have systemless root and mods without recompiling the entire kernel.

A bit off topic, but moderators don't mind too much as long as it's not a super long dialogue. Loopback is arguably worth mentioning here, since the Tab 3 8 is technically a Motorola device (Moto/Lenovo/IBM/Google...there's been a lot of acquisitions and mergers the last 10 years). Though, our /userdata partition is formatted EXT4. So any members contemplating the re-formatting of /userdata to F2FS would be strongly discouraged from doing so on these grounds.
[Android General] pndwal:
That's very interesting.

As I mentioned, seems most LOS iterations use EXT4 system partition and F2FS userdata and cache partitions as does my Huawei Ascend Y550 on LOS14.1, but I remember F2FS formatting was not possible in the early days. Certainly no problems now with magisk, nor is extra module needed, so guess kernels for custom ROMs must generally now be compiled with bug fix for F2FS. (Just as well as the module trick wouldn't work with F2FS cache either.)

Will you be interested to try to include this fix in LOS 14.1 kernel for our device, to enable formatting userdata and cache partitions to faster F2FS? - Guess it may even have this from original port already. :) PW
[Android General] MotoJunkie01:
Correct. Specific maintainers of LOS must patch the kernel for the EXT4/F2FS protocol on devices which are configured this way. The LOS 14.1 for the 850M, which I'm porting to the 850F, was originally ported from a Lava Iris device with a universal EXT4 filesystem on all relevant partitions. So, no -- I didn't have to patch the kernel for the F2FS /userdata scheme.

There are several utilities available that will allow you to format /userdata (and/or /cache) to F2FS on the 850F. In fact our TWRP build will likely do it (Go to Wipe>Advanced Wipe, select Data or Cache, and Repair or Change Filesystem. Now select Change File System and select F2FS from the menu). But, I wouldn't recommend doing so. Again, LOS 14.1 for the 850F has a kernel configured for a standard EXT4 /userdata partition (as does our stock ROM). Also, although F2FS certainly performs better in benchmark results over its EXT4 counterpart, implementing this change to the /userdata partition just wouldn't be worth the trouble. There are kernel tweaks such as custom I/O schedulers (noop, bfq, deadline, etc) and entropy mods which will improve benchmarks to EXT4 /userdata -- comparable to those of F2FS. This is also much less invasive. As you undoubtedly know with your experience with Android, it's damn hard to rebuild an eMMC partition table once it has been corrupted or loses filesystem integrity.
[Android General] pndwal:
Thanks for detailed information.

So with universal EXT4, I would have thought LOS flash would give errors / wouldn't see /data if formatted to F2FS in any case. I'm pretty sure that was the case with my Y550 until kernel gained support. Or are you saying F2FS might work?

Also, I used TWRP advanced wipe, repair, as you mentioned, to format from EXT4 to F2FS and vice versa in order to test - works fine. PW
[Android General] MotoJunkie01:
Let me clarify. You shouldn't have any trouble at all running F2FS /userdata on a stock or custom ROM (such as LOS). Any ROM is going to "see," or recognize, the F2FS /userdata filesystem. Problems only arise when the OS is required to mount a loopback protocol (.img file) as read/write. Unless the kernel is supportive for loopback operability, systemless modifications such as Magisk root are not going to function correctly. Reiterating, Magisk systemless root requires the path of /data/adb/magisk.img, which will not mount r /w on F2FS without kernel support. That is where the loopback bug workaround comes into light. It will use the /cache partition (must be EXT4) to create a type of symlink to the original path of magisk.img. The workaround will also regenerate merge_,magisk.img subsequent to each reboot, and will utilize it synonymous to magisk.img. This workaround allows you to have systemless root on a F2FS /userdata schemed device WITHOUT the need of a custom or modified kernel.

So as it stands, your device will function fine on LOS 14.1 (with F2FS /userdata). However, because the kernel does not support loopback devices, the loopback bug workaround must accompany systemless root or any other systemless mods.

By the way thanks for testing the TWRP re-format function. That is good to know. If you plan on trying F2FS /userdata, let me know if you see any significant differences in read/write speed and overall performance. I have implemented preset I/O schedulers and entropy tweaks into the LOS kernel to improve responsiveness and take advantage of the full capabilities of our EXT4 internal storage config. If you don't mind, perhaps I can talk you into some benchmarking tests, comparing EXT4 & F2FS read/write results with AnTuTu. Let me know either way. I'll find time if you cannot. Thanks
[Android General] pndwal:
Thanks for the extra detail. My Y550 must have the requisite kernel support. I thought F2FS data and cache didn't work before this, but may have been formatting system as F2FS that caused failed flash - its a while ago now.

I always use TWRP for formatting. In days when using link2sd / apps2sd I had many problems after formatting SD (for FAT/EXT4/Swap partitions) on PC too. Had to fiddle with block sizes, etc. No such problems when doing this from TWRP though.

Wasn't planning on trying F2FS /userdata without properly configured kernel support, but I guess I could if you want benchmark results. I've only flashed partitions before clean flash in past - I imagine format swapping erases data and I'd need to backup and restore data to do this. (Tricky with adopted SD, but I guess I could just backup and restore internal data and not touch SD, and SD should still work as encryption key is generally restored with internal data - would save this manually too just in case of problems.)

I have spare Y550 phones too (SD410), and could more easily run tests on two devices with identical LOS 14.1, one with EXT4 system partition and F2FS userdata and cache partitions, and one with all EXT4. Let me know if it would help. Regards, PW.
[Android General] pndwal:
Well.

Guess there will be no answer to this now. And no LOS14.1 port either. Other issues were of more importance, and now we have no OP. No OP for some 35 threads incl. threads for Tb3-850F, Moto E, Moto G and others.

He was a casualty in what can only be described as a train wreck. Nerves were stepped on, tempers flared, and the rest is history. Its all history.

I hope he'll be back to drive the train, but I'm not holding my breath.

I'm very disappointed it's come to this. Especially after hoping and looking forward to LOS ports arrival for some time, and knowing the initial release has been completed.

Thank you [MENTION=7383447]MotoJunkie01[/MENTION], for your efforts with our shared devices, and for the help, support and edification you offered to so many over the last couple of years. Hope you will recuperate and return, but wish you all the best anyway.

Sincerely, PW.
[Android General] Never_Sm1le:
From what you said, and his disabled account, could it be the worst has happened to him? I just felt weird when his account was disabled since he is one of the most helpful person on xda until I read your post.
[Android General] pndwal:
Hope not. Among other things, before account was disabled, he wrote:

So I guess he may surface again (here or elsewhere) or make contact, but I'm not holding my breath. He certainly was helpful to many at XDA but. PW.
[Android General] fender_gr:
thanks for the guide, i'm waiting to give me access to download the software to proceed.. thx
[Android General] pndwal:
Doubt you'll get it since OP is gone. Let us know if you do. PW
[Android General] Hemphiz:
Not sure if this is the file your looking for but here's a link anyhow

Twrp-flashable-TB3-850F_S100031_171010_ROW.zip

https://drive.google.com/file/d/1f271tqJXL3d2thSnDa-lcNlrwMwDZxQy/view?usp=drivesdk
[Android General] pndwal:
Hey [MENTION=4032180]fender_gr[/MENTION] - Looks like [MENTION=6939319]Hemphiz[/MENTION] found a working link to 850F ROM for you! (Twrp-flashable-TB3-850F_S100031_171010_ROW.zip). See his post above. Please give him kudos. (I shouldn't have doubted.)

Hope it does the trick. Regards, PW
[Android General] neobuddy89:
Can someone please upload twrp recovery for lenovo yt850? Link in OP not accessible.
[Android General] pndwal:
This is not Yoga tablet. Its TB3-850F.

For TB3-850F, go to https://xdaforums.com/android/help/lenovo-tab3-8-2016-custom-recovery-t3483454

Instructions, post #66.

Use TWRP from TB3-850M thread on Russian 4PDA site. Link in post #67. (To create 4PDA login, see post #69)

Alternative working links for TWRP, SU, instructions, post #71.

Relevant notes from Russian archive:

Important!

- Before installing the advanced recovery, you must perform the steps to unlock the bootloader.

Attention!

- After unlocking(bootloader), the system will be completely cleared of your data and settings!

- After installing the recovery, you must immediately reboot into it, otherwise there will be stock recovery again.

- After installing the recovery, subject to the permission of changes in the system, it is mandatory to install SuperSU, otherwise the system will not boot.

Regards, PW.
[Android General] neobuddy89:
Would you have 850M TWRP link?

Looks like it's expired on Russian page.
[Android General] pndwal:
Its not expired, but you need to log in to get 4PDA hosted files, and learn some Russian longhand numbers to enter capcha code. Check link I provided.

You'll notice I also provided alternative download link to save you the trouble with login. This works fine.

Be careful with TWRP made for different device. (Assuming you want it for yt850). You can easily brick device as partition tables etc will be different even if device uses same processor. I wouldn't do it. PW.
[Android General] neobuddy89:
EDIT: Thanks.
[Android General] Mufrad:
you sir are a life saver. thanks for the link, i was searching for a flashable rom for this tab for a while, all the motojunkie links are dead.
[Android General] RatzLord3125:
My lenovo tab3 8 model number is TB3-850M instead of TB3-850F. Do I need to add/modify any step that you have mentioned??
[Android General] pndwal:
TWRP was originally made for 850M, so you can use this. Can also use latest Magisk for root.

However, 850M / 850F use different firmware and have different processors, hardware blobs etc. We only have stock ROM / modified stock for 850F, whereas LOS14.1 and RR Rom are available for your 850M. PW
[Android General] wezroot2k:
so i just now took the risk of flashing the ported version of lineage os 14.1 for tne tab3-850m and here what

happen

the rom was successfully flashed but upon restarting i think i am caught a boot loop

so gonna try and see if i canget to boot to os wish me luck and any advise will be appreciated

update: the rom actually boot after some time not long and i must looks quite good but i turned off my device

and it bootlooped again so keeping an eye on to see what happens next so i will keep you guys posted.

UPDATE: OK so I think after a reboot or shut down the device will restart a few time before actually booting to the OS so i sat its good to go. Gonna test a few more stuff and let you guys know what going on Thank you

---------- Post added at 08:38 PM ---------- Previous post was at 08:16 PM ----------

UPDATE: LINEAGE OS 14.1 NOUGAT FLASHING

Ok as stated in the above post if the device is restarted or shutdown upon powering the device

it will restart a few times before actually booting to the OS (don't know y:confused:) so any suggestion will be

appreciated. also i find this is a useful upgrade for this device for me so any help to stablize this port will also be appreciated thank you
[Android General] pndwal:
Can we take it you are flashing to TB3-850M device, not TB3-850F? PW