I recently started using postmarketOS again on my FP 5.
Initially, I struggled to flash it into slot B, but after switching to slot A, I was able to install it successfully using the Web Flasher.
I still buggy set up and thinking to flash it again, but before I’d like to learn and get better understanding about it
Could someone please explain:
What the purpose of the A/B slot system is?
When and why you’d choose to flash to slot A vs slot B?
Are there best practices for managing or switching between the two?
Seamless updates = Installing an OS update in the background on the inactive slot while the user can meanwhile continue to use the active slot. The mandatory reboot then just needs to switch the active slots.
Prior to this mechanism the whole installing of an OS update took place when rebooting, and thus for the user the phone was out of operation for a perhaps lengthy period of time.
There’s a fallback in case an OS update fails.
In case the update process discovers upon boot that booting the updated slot doesn’t work, it will revert to booting the other slot, where there should still be the functioning OS prior to the attempted update. Android rollback protection now prevents the user from doing this freely regardless of a perhaps older patch level on the other slot, but during the update process this mechanism is in full effect.
A new install from scratch should install both slots.
But in the end it doesn’t matter that much, the slots get switched around during OS updates anyway.
There shouldn’t be much to manage for the user, but if you want to play around, there are fastboot commands for the phone in fastboot mode (aka bootloader) to deal with the slots, easily findable in the internet (or in the forum) for everybody interested.
With a locked bootloader the possibilities might be limited, though.
This all is from the Android perspective.
I don’t know whether anything would be different when using postmarketOS.