[T-Mobile Samsung Galaxy S 4] Exel:
This thread was originally created by [MENTION=2288048]Hawke84[/MENTION] over in the i9505 forums. A lot of people are unaware of KNOX or have no idea how exactly it works so I thought we should have a thread like this in our forum as well. I have sent [MENTION=2288048]Hawke84[/MENTION] a PM and would like to let everyone know I take no credit for this idea. Huge thanks goes out to [MENTION=2288048]Hawke84[/MENTION].

Please feel free to ask any question here and i'll do my best to answer it but hopefully some of the other members who know a bit more will also join in and help answer some of the questions people have.

What we know so far:

1. Upgrading to newer 4.3 Samsung firmware will most likely upgrade the bootloader to knox bootloader. This will give an additional 2 lines in download mode about knox status.

2. If the Knox Warranty Void line says 0x1 then you cannot use KNOX Software on your device. Your device has also been flagged as insecure. This means that if your workplace / company supports bring your own device to work for corporate emails, etc. and they use KNOX, your device will not allow this.

3. If the KNOX Warranty Void line says 0x0, KNOX will work and your warranty is still valid.

4. With the new KNOX Bootloader, root will work. However, rooting with CF Auto-Root will trip the KNOX flag. Someone else has developed a way to root without triggering the KNOX flag. (Root de la Vega)

5. If you try to downgrade to an earlier firmware / bootloader it will set the KNOX flag to 0x1 (Void)

6. Once the KNOX flag gets set to 0x1, there is no way to set it back. (Yet!)

Let me clarify some things. The KNOX processes and functions are already on the stock ROM, most devs remove them, though. So many of you with custom ROMs haven't seen anything related to KNOX.

What the new T-Mobile update (when it gets pushed out) is most likely to come with is a "KNOX Bootloader" which will introduce a thing called "KNOX Flag" which is similar to the old counter we're all used to. This is the counter that [MENTION=631273]Chainfire[/MENTION] was successful in resetting with his app, Triangle Away.

Unfortunately, [MENTION=631273]Chainfire[/MENTION] or anyone else for that matter, has not been able to reset the KNOX flag.

The KNOX flags is this:

0x0 = You have not tripped the KNOX flag.

0x1 = You have tripped the KNOX flag.

Again, once you trip that flag, rooting, flashing a custom recovery, etc.. there is NO way to reset it as of now. And any KNOX functionality on your phone will not work. But the worst part is Samsung will refuse warranty on your device if they see a 0x1 in your bootloader.

Another thing.. on the new bootloader, if you try to downgrade, even with an official Samsung firmware, it will fail and you will trip the KNOX flag.

So once you're on the new bootloader, there's no going back.

There's been speculation that there's an eFuse at play here.

Anyway, for this reason.. I am suggesting you all disable OTA updates and wait until a ROM is built without the new bootloader and all the functions (Wifi, MMS, etc.) are working.

Useful links:

[Q&A][i9505] Knox Q&A / Discussion Thread - ask questions here!

[RESEARCH] Samsung Knox: Warranty Void Behavior

Everything KNOX...