Quick question about jailbreaking before upgrading

[Cameron08]

I have an Iphone 3GS, old bootrom and running version 3.1.2

I want to upgrade to 4.0 and be able to jailbreak. I read the Dev Team website and it looks like all I gotta do is update all the way to 4.0 but I want to make sure it will work.

Do I need to back any files or ispw files or anything up before upgrading to 4.0 then re jail breaking?


Kind regards,
Cameron

 

[Applejuiced]

No, you read wrong or didnt read carefully.
You dont update to official 4.0 and then JB.
You update to custom IPSW created with pwnage tool from your already JB iphone on 3.1.2 with the early bootloader.

Read:
These are instructions on how to jailbreak your iPhone 3GS on iOS 4.0 using PwnageTool for Mac.

Currently, PwnageTool only works on previously jailbroken 3GS devices with the old bootrom.

● If you have a Jailbroken iPhone 3GS with the OLD BOOTROM and you DID NOT use Spirit to jailbreak then you can create the ipsw with PwnageTool 4.0 and restore with your jailbroken recovery mode.
● If you have an iPhone 3GS with the NEW BOOTROM this is NOT supported by PwnageTool 4.0. Please don't use this tutorial

Follow this:
http://www.iclarified.com/entry/index.php?enid=10217

 

[Cameron08]

Thank you for clearing it up! I feel more confident now.

Cameron