Would it be possible for a phone to have a bootloader where you can select a previous patch, in case the latest has issues?
I don’t know the details of Android/AOSP, but since it’s Linux at the core and desktop OS have these features, why not?
Or do these patches (like 15.15.2 that’s currently bricking FP4s) include blackbox bytecode for the broadband processor?
Well, even if it were possible
- it hadn’t helped with 15.15.2 as the phones showing the problem are virtually “dead”. So you’re not able to start fastboot mode, so no switching to anything else anyway
- with the two slots there’s already a similar mechanism: if the device fails to boot several times after an applied patch it reverts to the previous version
“Currently bricking FP4s” is IMHO a little bit stretched as the patch has been redrawn days ago so I don’t see how it could still brick a device “currently”.
There are bricked FP4 devices, which worked prior to 15.15.2 and are currently bricked by 15.15.2 being installed on them. The updated being withdrawn from deployment doesn’t change that.