Right. You'd have to flash the firmware to the other slot first before being able to boot that slot, as you mentioned in an earlier, very informative post
. But as I understand it, if you got into a bootloop and the device tries to revert to the inactive slot, it would be able to boot into that slot because the firmware had been previously flashed to that slot? Or is this incorrect? Seems I remember (at least I think I do in my old age, lol) some people mentioning that after a bootloop (it has to bootloop 3 times in a row to do this if I remember correctly?) the device reverted to the other slot and was able to boot into that other slot (they noticed they were on an older firmware version afterwards). Maybe when the device does this it does something (AVB related or writes the system_other image?) to make it able to boot to that other slot under these circumstances?
Just to be clear,
Let's say I'm on A and A is bootable
I flash factory to B
B is bootable and now active.
I never tested forcing B to become unbootable and checking if the system switches to A and boots fine.
My guess is that it won't work for sure, because A's system is overwritten by that fact that I flashed to B.
So I did two different tests
1- Restore a backup of system to A, and switch slot to A (making sure that bootctl reported slot usable), A was still not bootable, the system would try 3 times and eventually mark it unbootable and revert to B
2- I deleted system_other from the factory image before flashing B, B was bootable, and I switched to A, this time A's system was untouched, so I expected it to boot, but it still failed because of AVB (on newer devices) but passed on older Pixel XL