KitKat to Marshmallow update diary, kept apps and settings, rooted

I managed to upgrade my Nexus 7 2013 LTE from KitKat to Marshmallow using factory images yesterday and took some notes. All apps and settings kept (or at least I haven't noticed any issues other than no Xposed) and rooted. I figured someone might find this useful.

So, short version: upgrading directly from 4.4.4 to 6.0 with factory images didn't work without wiping data and where's the fun in that? So I took a longer route and went 4.4.4->5.02->5.1.1->6.0.0. It's possible I could've gone from 5.0.2 to 6.0 or 4.4.4 to 5.1.1 directly but I'm not going to try and see if that's the case. Enjoying Marshmallow now.

Basically, I did the same thing for all three update steps:

1. Unpacked factory image, rebooted to bootloader, flashed bootloader, radio, system.img, boot.img, cache.img. I rebooted to bootloader after flashing bootloader and again after flashing radio, same thing the flashall.bat does. Don't know if it matters.


2. Booted to TWRP recovery, flashed supersu zip and renamed /system/recovery-from-boot.p to keep TWRP.


3. Booted system and grew some gray hairs while the boot animation went on and on until it finally got to the long "optimizing apps" phase.

For 6.0 I flashed a modified kernel and supersu beta 2.52.

So, enjoying Marshmallow now. No issues so far. Root cloak detectors seem to be becoming a plague and I've only used an Xposed module for that.