What is the difference and why is it a big concern?
Why does iPlus talk so much about this?
very noob i know but i want a unlocked iphone and want to know everything first and choose best route mainly iPlus vs. ZiPhone.
Right now there are 4 different Bootloaders, [yes you read right 4]. These are:
1. Bootloader 3.9
2. Bootloader 4.6
3. Bootloader 3.9 Fakeblank
4. Bootloader 3.8 (Recent appearance)
Now, I'll explain a bit more on these different bootloaders.
Bootloader 3.9 was the first bootloader to be used on iPhones that were made on week 45 or earlier in 2007. This Bootloader [3.9] allows the iPhone SimFree (IPSF) paid unlock aswell as GeHot's IPSF-like free unlock. Also, this bootloader allows you to downgrade your Baseband (which controls your Wi-Fi, EDGE and Calls) firmware. Downgrading baseband is useful when you updated by mistake or/and want to go back down to a previous iPhone firmware. Bootloader 3.9 does not allow bootloader update
Bootloader 4.6 is the current bootloader being placed on iPhones as of Week 45 and later iPhones of 2007 and all 2008 iPhones. This bootloader does not allow your baseband to be downgraded, so once you updated, you are stuck there. Also, this bootloader does not allow the IPSF unlock. As you may remember this bootloader caused many problems when it was reviewed by the Dev-Team to look for a software unlock. Now, thanks to GeoHot, this bootloader [4.6] can be unlocked. One important exploit in this bootloader is that it can allow you to downgrade itself to the earlier 3.9 which is good if you want to downgrade baseband or apply IPSF-like unlock.
Bootloader 3.9 Fakeblank (BL 3.9FB) is a modified bootloader created by Geohot and the Dev-Team. It has all the capabilites bootloader 3.9 has, but has one great exception. This bootloader, since it's modified, can allow you to updgrade back to bootloader 4.6. One big flaw of it, is that if you downgrade your firmware to 1.1.1 or earlier the bootloader seems to disappear and a new bootloader appears (more on that next).
Bootloader 3.8 is very, very new. This bootloader is a mistake made by the iPhone when installing firmware 1.1.1 or earlier on a BL 3.9FB. Since, its new not many information is known, but here are some things. This bootloader occurs because 1.1.1 or earlier firmware thinks there is no bootloader (BL 3.9FB makes it look as though there is no actual bootloader). So the strongest suggestion is not to downgrade to 1.1.1 or earlier when using BL 3.9FB until the mistake is corrected. The greatest worry of this Bootloader is the fact it has all the exploits of 3.9, which means no bootloader upgrade. After this info, not much is really known of bootloader 3.8.
=== Hope this helps you inquiries. ===
Why is it possible to do a software downgrade from 4.6 to 3.9 but not possible to do a software upgrade reversely?! (I have heard of some hardware method for this!!)
Having said that the beauty of this is that if you have used iPlus/iLiberty that you can go back to 4.6 before you update although you would lose the unlock again so that would only work if you have an official iPhone contract again!
Basically your right!
4.6 can be unlocked but only with the 1.1.2 baseband (the baseband is the phone modem basically) - which means features such as locate me in google maps won't work - in addition to having the wrong baseband for the firmware - which although isn't a huge problem isn't great!
Independence (on Mac) and iLiberty+ if you DON'T check the bootloader downgrade option can do this for you.
IF you want the lastest firmware unlocked with the correct baseband then you can ONLY do that if you have bootloader 3.9.
ZiPhone downgrades it and it can't be put back to 4.6.
iLiberty+ downgrades it to a hacked version that CAN be put back to 4.6.
Having said all this if you have not already unlocked your phone wait for PWNED to come out later today (if its not already out when you read this) as it appears that may be a method that makes your bootloader not matter anymore!
Im getting my iPhone tomorrow and since i don't live in US i have to jailbreak it.
Jailbreaking is 3rd party apps
Unlocking is using any SIM other than ATT.
Jailbreaking is 3rd party apps
Unlocking is using any SIM other than ATT.
You cannot unlock it without jailbreaking it first.
You WILL Be able to upgrade without any issues to the new firmware.
Ironically enough iPlus/iLiberty users may have issues however!
Let me explain!
3.9 came on all original US models - so the 2.0 firmware will work as it does now.
Obviously if your not on an official iPhone contract then you won't be able to activate the phone unless it is jailbreaked.
It seems very likely that within hours of it coming out a jailbreak method will be released as the dev teams have already got into the beta.
However if you used iPlus/iLiberty to UNLOCK (and your phone was 1.1.2 or newer out the box)- then you will have the 3.9FB bootloader. IF Apple includes other bootloader files with the firmware update then there is a chance that it will mess up the phone in someway as is happening with restoring to 1.0.0 and 1.1.1 firmwares now (ie going from 3.9 to 3.8).
Having said that the beauty of this is that if you have used iPlus/iLiberty that you can go back to 4.6 before you update although you would lose the unlock again so that would only work if you have an official iPhone contract again!
Of course if there is no older bootloader files in 2.0 then there is no reason why you can't upgrade to 2.0 - although again unless your on an official contract yourl be locked out!
However this whole argument seems pretty redundant as a news article on iPhone atlas from yesterday seems to suggest you can upgrade and keep your existing unlock if you use the devteam method!
http://www.iphoneatlas.com/2008/03/26/iphone-os-20-may-leak-publicly-soon/
I think the point here is that its best to wait for a dev team release before upgrading simply because even if you have an official iPhone contract you may as well jailbreak and unlock if possible at the same time as upgrading! as it seems that the DevTeams are hot on it!
However if you used iPlus/iLiberty to UNLOCK (and your phone was 1.1.2 or newer out the box)- then you will have the 3.9FB bootloader. IF Apple includes other bootloader files with the firmware update then there is a chance that it will mess up the phone in someway as is happening with restoring to 1.0.0 and 1.1.1 firmwares now (ie going from 3.9 to 3.8).