[LG G8 Guides, News, & Discussion] kevin_bouchard:
Thanks for the lead, I talked to vl48 and confirmed that we can flash over it. However you will loose fastboot unless you nuke the laf partition. He recommended keeping either Pie/engineering bootloader on the inactive slot or Android 10 rooted on both slots.

One caution, do not run a non-rooted/exploitable rom in your active slot. If you get an OTA update writes to the inactive slot/engineering boot loader than you lose fastboot and the ability to exploit and say good bye to custom roms!

If however you are always running a rooted rom(or exploitable), even if your phone takes an update, you just need to switch back to previous slot and can continue on.

Ideally we would want to completely break OTA so we can completely avoid this. There are a few debloating guides around so I'll take a look at those in the coming days.

Courtesy of vl48, Nuking laf dd command:

dd if=/dev/zero of=/dev/block/bootdevice/by-name/laf_a

or _b for b slot...

Really too bad we cant crossflash a kdz from another phone and use just fastboot. We wouldn't have to worry about getting updated as we could just reflash with the kdz and then use fastboot to load recovery/our backup/custom rom(all assuming BL is already unlocked).

I've included out telegram conversation if anyone is curious.

Kevin Bouchard, [07.06.20 15:58]

Hi vl48, I asked the question if the engineering bootloader had to remain on the G8 after being BL unlocked and dm verify disabled. siulmagic suggested I ask you, do you know? My thoughts were it would be nice to have one slot for rom testing and the other for daily use(though factory resets seem to be needed so maybe its usefulness is very limited). Also I was told that fastboot would also disappear without it. Had me thinking though that if the OTA app isnt blocked in some way, it would overwrite the information in the inactive slot and replace the bootloader at the same time (maybe not all updates replace the bootloader).

vl48, [07.06.20 15:59]

Hi Kevin! Firstly can you share which version of G8 you are using?

Kevin Bouchard, [07.06.20 16:00]

I\m using the sprint version

Kevin Bouchard, [07.06.20 16:00]

gm820u I think

vl48, [07.06.20 16:00]

Oh...

vl48, [07.06.20 16:00]

Well with Sprint you need to have always one slot on Pie with engineering boot

vl48, [07.06.20 16:01]

Or 2 rooted Android 10 slots...

vl48, [07.06.20 16:01]

One should have LAF nuked so fastboot is enabled...

Kevin Bouchard, [07.06.20 16:01]

right I read something about nuking LAF

vl48, [07.06.20 16:02]

Yep zeroing LAF will bring you fastboot

Kevin Bouchard, [07.06.20 16:03]

so say your active slot is rooted, and an OTA gets pushed and overwrites the engineering bootloader and then switches the slots, do you think it would brick. Or is it just a matter of switching slots back (before the next update), get back into root, then reflash the engineering bootloader with DD and back to the same state as before LG pushed the update?

Kevin Bouchard, [07.06.20 16:04]

my main concerns is LG pushing an OTA as I know that even disabling them in the app, LG still downloads and writes it to the inactive slot, it just doesnt switch the active slot till you say yes to install.

vl48, [07.06.20 16:04]

Engineering bootloader can be flashed only on Pie slots

Kevin Bouchard, [07.06.20 16:05]

really? I thought the root guide only had me flash the bootloader and I had android 10 on the inactive slot

Kevin Bouchard, [07.06.20 16:05]

though I never booted the slot, just went straight to fastboot

vl48, [07.06.20 16:07]

Engineeriong abl we are using is from Pie and will never boot anything else from Pie, again the boot is from V50 so touch will not work on G8

Kevin Bouchard, [07.06.20 16:08]

ok this is starting to connect the dots, explains why touch wouldnt work. also explains why the guide just had us flashing xbl, xbl_config, abl and laf from pie and thne the bootloader. Dont need the system partitions are we just using fastboot

Kevin Bouchard, [07.06.20 16:09]

so once bl and dm verify is disabled, if the engineering bootloader is overwritten, it just means we loose fastboot (unless laf is nuked), is that correct?

Kevin Bouchard, [07.06.20 16:10]

or is there some other weird signature check that I'm not tracking that requires the files in the inactive slot to stay on pie/engineering bootloader so the other slot can still boot?

Kevin Bouchard, [07.06.20 16:11]

man, a firehose file would make all these questions moot. one can dream eh

vl48, [07.06.20 16:12]

Yeah... with firehose things will become much more easier... sadly it is not yet avaliable

Kevin Bouchard, [07.06.20 16:19]

and maybe never will ;( . I guess you answered my question by about the engineering bootloader when you said two android 10 rooted slots as that would require replacing the engineering bootloader. The biggest risk then would be using the phone without root and having an OTA applied which would effectively lock you out of getting root back. Safest being like you said, both rooted or one staying on PIE/engineering. Thanks for the insight!

Kevin Bouchard, [07.06.20 16:27]

do you mind if I copy/paste our conversation to XDA?

vl48, [07.06.20 16:30]

no of course

vl48, [07.06.20 16:32]

Nuking laf dd command:

dd if=/dev/zero of=/dev/block/bootdevice/by-name/laf_a

or _b for b slot...

Kevin Bouchard, [07.06.20 19:47]

awesome thanks for the laf nuking command and thanks!