Got any sources on that? 
The AvB specifications I linked above are directly by Google, and they specifically mention that the rollback index should be cleared.
Would be strange for Google to offer a bootloader that violates their own directive ā¦
If you donāt lock your bootloader, none of this matters and you can install as many different operating systems as you want without bricking your phone.
The rollback index only comes into effect once the bootloader is locked.
As I understand it, Itās the same anti-rollback mechanism as used on Google phones since Pixel 6, which uses the eFuse feature of the Snapdragon SoC:
https://www.xda-developers.com/google-pixel-6-series-android-13-anti-rollback-bootloader-version/
The rollback protection on the Google Pixel 6, Pixel 6 Pro, and the Pixel 6a is materialized through electronic fuses (eFuses). An eFuse is like a write-once flash. Once you flip those bits by writing something into them, thereās no going back. After āblowingā an eFuse, itāll stay written with that value forever.
Thatās reassuring if this is true. However, what initially worried me was Murenaās website here:
https://doc.e.foundation/devices/FP4/install
(see ācautionā section in red, and examples)
This section is after you have unlocked the bootloader. There is no mention of re-locking it in the steps up to that point. Yet they still warn that if the anti-rollback is triggered, you will brick your phone.
Well, if thatās the case, that really sucks, but it certainly would explain why itās not working as itās supposed to 
Iām gonna give Fairphone the benefit of the doubt here, never attribute to malice ā¦ etc., but if they donāt explain it / fix it, the outcome is basically the same.
You will, if you trigger it (and OEM unlocking is deactivated), but itās not active unless you lock the bootloader and if you check fastboot flashing get_unlock_ability before locking it, you can usually unlock it again even if you triggered it.
Beware, thatās the case for the FP4, other phones might even check the rollback index in an unlocked state, itās up to the manufacturer to decide.
Interesting to see them used in that context. As I understand the article, the eFuse āonlyā prevents going back to Android 12 when you updated you Pixel phone already to Android 13 once. It doesnāt sound like it affects the rollback protection in general. I personally havenāt tried to go back to Android 12, but I would assume that we had heard already of some cases if this would be impossible.
The variable mentioned in the article isnāt even set in my case (iodĆ©OS with Android 13):
(bootloader) version-bootloader:
But as āThe Snapdragon processors have a OTP fuse bank region referred to as eFuses (QFPROM) which can be used to store disk encryption keys.ā, it doesnāt sound like they would run out of space for single bits quickly. I havenāt found any statements regarding the size, though (searched not too deeply).
In /e/OS OEM unlocking is active (I mean you can always move the slider from enabled to disabled and vice versa) even if the bootloader is unlocked.
I meant anti rollback protection isnāt active, unless the bootloader is locked 
I just want to mention that the fact that this whole eFuse thing even exists is unacceptable imo.
Itās āyours to open, yours to keepā and itās also my goddamn right to install any crappy old Android version I want on it without my phone - that I bought and I am responsible for - destroying itself. If I get hacked then thats my problem, but itās not Googleās (or anyone elseās) job to patronise me about what I do with my devices.
What you can do is down to the device, and given the complexity of the chips and how they are made for a global audience itās unrealistic to think you can do what you like.
A ridiculous example is : given the value and cost It still doesnāt toast bread but then my oil filled radiator doesnāt either.
However my old parabolic one bar heater can, be used to boil water and make toast, I can even use the mirror suntan 
It seems that had I had toasting in mind I would not have bought a radiator, but I did, well actually I didnāt ~ I use a wood stove for heating and cooking in the winter and solar in the summer, neither of which provide me with toastā¦
So maybe some mods can be done to the phone or maybe trade in in for one that you can install A4 on.
There are no rights, just privileges and there are limits to what the user has.
Er, WTF?
I paid for this thing. More than that: I bought a āFairphoneā. The whole āraisin dāetreā of fairphone is to avoid landfill, but if they sell phones which brick themselves, it completely defeats that.
Itās a bit like buying what you thought was a freehold house, only to find out itās leasehold, and you are beholden to some landlord. And if you paint the walls the wrong colour, they will evict you, and not even refund your money.
Just because itās a ācomplicated chipā shouldnāt mean that it has a self-destruct mechanism on it controlled by some third-partyā¦ Iām sure youāve tripped BitLocker on Windows once or twice because you installed a different RAM module or SSD. But your CPU doesnāt fry itself when you do that, it just erases the data (or rather, the encryption keys), which is what you told it to do when you enabled BitLocker. But if someone (say, Apple) sold a PC that rendered itself useless if the wrong software was installed, they would be taken to court. Especially if they had advertised it as āgood for the planetā or somethingā¦
I would strongly disagree . .
The Fair is about the miners and factory workers welfare
Yes thatās why I donāt use solicitors for such, I read the detail for weeks.
Donāt misinterpret my arguments for me thinking the FP is a good phone in terms of user experience, I wouldnāt recommend it to anyone.
But I made a choice to support Fair (wages etc.) and thereās no going back on that.
Then why do they make replaceable modules ? I thought the main point was about repairability, and that āfairtradeā was a secondary āvalueā.
Our core value of longevity is designed directly into our smartphones. We created the Fairphone 3 to last ā both in its original design and in making the repair as easy as possible. This made it the only smartphone in the world to be awarded a perfect iFixit score for repairability.
I guess they didnāt create the Fairphone 4 to lastā¦
Thereās honesty for you. 
Iām sure there are other ways of supporting wages for poor Cambodians/Guyanans/etc than paying them a better wage to go down a mineshaft, thoughā¦ 
The company set out to source fairer traded minerals and then decided a phone would be a good place to use them and promote the idea start and that lead to wages . . .
Page 1 of About us https://fairphone.com/en/story
From the earth to your pocket, a smartphoneās journey is filled with unfair practices. We believe a fairer electronics industry is possible.
Fairphone builds a deeper understanding between people and their products, driving conversations about what āfairā really means.
Then it degrades into more general waffle
By creating a more sustainable smartphone, weāre demonstrating the endless possibilities for a fairer future ā for everyone.
Just be happy that you can be nice, each of us has choice over the things āweā do.
It seems repairability and sustainability are the buzz words and thatās what you heard, the buzz ~ the buzz of the āmore money making machineā
Not if itās to install the software we want on the phone we bought, apparently.
The real āmoney making machineā is Google, of course. And it seems that nobody can escape their monopolistic reach.
Just one of many and thatās the default licence on the phone, mess with the phone and you mess with Google
You should keep in mind that we donāt even know yet if the FP bootloader is even using this āfeatureā and if so, how many times one could update the phone before this is even getting a problem.
At least at the moment, itās very unlikely that the option is active, since Google activated it on itās newer Android 13 versions and the FP4 just received Android 12.
This is not a Fairphone thing ā itās an Android thing, and provision of these efuses is a requirement for a SoC to be able to run Android 13 (at least) at all. The fuses are not blown on every update: theyāre blown on every security vulnerability fixed in the bootloader, which would allow a complete bypass of signed boot etc. These are rare: I think there have only been something like three or four total so far in the entire history of Android. Itās just that one of them was fixed in the run-up to Android 13, so downgrading is impossible.
ā¦ well, except that this massively pissed off developers who were only trying to test their apps on Android 13 while using Android 12 themselves, and were rather unhappy when switching back after testing permabricked their expensive Pixel phones ā so now Google provides an AOSP release of Android 13 for testing which does not blow the fuses. It attests itself as for testing only, though, so things like banking apps are unlikely to work with it. Itās not updated often either.
(Personally I loathe all this stuff too, but itās not Fairphoneās fault and they canāt avoid it unless they want to stop using Android altogether. Blame monopoly operating system provision by megacorps that donāt care about freedom.)
^
But I guess the main thing that I am pissed at -fairphone- for, is this stuff:
āInstall now to control when your device updatesā ??? (giving the illusion of control, but giving no choice)
This basically forces me to install a potentially poisoned update (from the point of view of my eFuses and being able to revert my Android version) whether I like it or not. I really do not like getting updates forced down my throat, especially if itās impossible to revert those updates if I donāt like them, and especially if they also have the potential to damage the device and make it unable to run some software in future.
And requiring a code from their server to unlock the bootloader is something I find on obnoxious from fairphone, too.
You can just press the home button and the popup goes away. I did this almost for an entire year until LineageOS came out last month.
Regarding the bootloader: Iām completely with you on that one, but the problem is that FP probably wonāt be certified by Google if they shipped the phones with an unlocked bootloader (like they did with the FP1 iirc), which would prevent them to preinstall Google apps on them and while I think that that would be amazing, >90% of the customers unfortunately want to have those apps, so FP could just as well close down if they didnāt do it.
Fairphone targets a wide audience and so forcing security updates is probably a good decision to prevent a lot of unpatched devices and unusable apps. You have always to keep in mind that the default Fairphone user just wants to make a fair choice regarding hardware and doesnāt want to lose the comfort of the Android ecosystem.
If you feel advanced enough to decide to not install security updates to fix known vulnerabilities, you can simply disable the update mechanism. Like @nickalcock explained, the number of āunburntā eFuses will likely not become a problem in this century.
