Note: Before You can flash any GSI, You have to unlock Your bootloader. To do that, simply type: fastboot oem unlock . Just remember that it will wipe Your data!
Important: Flash 5.1.6 or above before flashing v20. It looks like 5.1.6 fixed Treble problems. Files have been updated to: 5.1.7
Step 1: Download any GSI rom You want, in this guide I'll be using Phh Treble latest build: Phh Treble A/B v20 with GApps and SU
(Make sure to extract it before flashing. You can do that with 7zip)
Step 2: Download this zip. It contains stock VBMETA as well as stock boot image, just in case if Your device is rooted. Link: Treble OP6 Files 5.1.7
Step 3: Extract those files on Your desktop for example and open terminal/cmd in the same folder as Your files. (Before You can do that, You should download latest minimal ADB and Fastboot available here: ADB & Fastboot XDA Thread Link ) Now. Copy and paste those commands:
fastboot --disable-verity --disable-verification flash vbmeta vbmeta.img
This command will let You boot non OOS roms, like Phh Treble or any other Treble GSI.
fastboot flash boot_a boot.img
fastboot flash boot_b boot.img
Those commands will flash stock non rooted boot image to both of Your boot partitions (Treble roms need slightly different root that's why we need to use stock boot image for now)
fastboot flash system_a system-arm64-ab-gapps-su.img
fastboot -w flash system_b system-arm64-ab-gapps-su.img
Okay, these commands will flash Phh GSI to both of Your partitions. The only difference is that second command will wipe Your data partition which is most likely required to have a bug free boot. So backup Your data before!
Aaand that's it! Enjoy Your new GSI rom.
Thanks to Dewang Rocker for making a tutorial video! Make sure to like and subscribe
And one more Thanks to @AxM2 for posting my guide on Github!
OnePlus 6 Treble Github Page
Q: Does this method work for all GSI images?
Yes! It should work fine, as long as Your GSI supports A/B partitioning. Most Devs build A/B GSIs so no worries.
Stock camera has problems with focus, but if You install OOS camera it works fine.
Notch is covering screen a little.
Q: I want to see some screenshots!
Phhusson for Wonderful GSI!
FunkWizard for latest firmware!
@dylanneve1 for being an awesome friend and helping me with many of my projects.
OnePlus for OP6 and releasing updates that are actually useful!
James Muir for Pixel 2 Guide on Github.
Google for creating Treble for us.