* All credit goes to Chinese developer Cofface *
This should be the easiest way to root the i9500 (yes, the so called 8-core one) by now.
Tested on FW I9500ZCUAMDG and should be working on others.
1. Based on CWM 126.96.36.199 (Thanks CM Team!)
2. ROOT your phone
Just download the recovery and unzip it, flash the cofface_I9500_cwm_recovery_en_new.tar as PDA in Odin.
Then turn off the phone and enter recovery by pressing Vol Up+Home+Power keys, and select ROOT YOUR PHONE, reboot, DONE.
Download: Hotfile Dropbox
update: Some Russian FW users reported this will not work, i've inform the developer Cofface and will update later if he fixed this. And here is a way to root Russian FW.
update2: I've talked to Cofface and he is on vacation now but if you need further helps, feel free to contact with him via Gtalk: email@example.com
update3: Here is a video tutorial by ashwin123, thanks!