Galaxy Nexus has got UNOFFICIAL Marshmallow ROM update, here it goes:
Galaxy Nexus ZMod Marshmallow ROM
WARNING:
Installing custom ROM requires a custom recovery to be installed on your device, which may VOID your warranty and may delete all your data.
Before proceeding further you may consider backing up your all data.
Please visit the Disclaimer page below to agree with the risks involved and proceed before flashing this ROM to your phone:
ROM Disclaimer link
Installing custom ROM requires a custom recovery to be installed on your device, which may VOID your warranty and may delete all your data.
Before proceeding further you may consider backing up your all data.
Please visit the Disclaimer page below to agree with the risks involved and proceed before flashing this ROM to your phone:
ROM Disclaimer link
Installing CyanogenMod 12 on Galaxy Nexus:
Make sure that you have the the bootloader unlocked and installed a custom recovery. If you don't have a custom recovery then follow the below link:Installing custom recovery for Any Nexus phone.
Then you have to get the CyanogenMod 12 ROM zip file over here:
CyanogenMod 12 ROM download link
SuperSU ROOTing package v2.27 by chainfire
This ROM does not contain Google applications like Gmail, drive, maps etc. so download the below GApps zip package.
Google Apps download link
It is recommended to install either NANO or PICO version of GApps from the above link.
Consider taking a backup of your OLD ROM before installing this new ROM.
STEP 1:
Copy the ROM, GApps and SuperuserSU package to your phone. STEP 2:
Enter into the custom recovery. Do a Factory Reset/Wipe Data and Cache partition.
STEP 3:
Install the ROM, Gapps and superuser recovery flashable zip packages using the custom recovery. STEP 4:
Reboot your phone to enjoy the ROOTed CyanogenMod 12 ROM on your Galaxy Nexus phone. Source:
Xda-Developers