This is specifically the Galaxy s3. Out of curiosity what are these partitions exactly. Are they part of the android OS or something lower level than that? If I were to delete everything in these partitions will I brick the phone even after a complete factory restore from "Download mode"? If these are not in fact android partitions why do some ROMs flash them? What is the difference between /firmware and /efs and are these flashed with most ROMS?

I've been googling the partition structure of my device and these things are not clear. Please help me clear them up :)

2 Answers 2


According to this linky here this is what it has to say

What is EFS? It is a place that stores your Android smartphone important data like Wi-Fi, Bluetooth MAC address and IMEI (nv_data.bin).

After reading the above linky, it would be prudent to make a backup of that partition otherwise well and truly hosed! :)

As for /firmware I am guessing that is where the original stock firmware goes into when updating via the official route a lá Kies.

If anyone has a better insight feel free to comment, and I will gladly amend this accordingly :)

  • I read that link before posting here. I do not have an IMEI as I use a CDMA phone. There are a lot of "nv items" I can edit through a tool called QXDM however I'm not sure if they are reading from the same EFS partition. Is this partition completely separate of the Android OS and actually a separate NVRAM chip that holds radio information?
    – user974896
    Commented Aug 10, 2012 at 0:54
  • There's some partitions that are "best left alone" even though I can understand your curiousity! :) That partition - actually do this - enter this from adb shell, enter mount, does it show up in the list, if not, they are "hidden" from Android OS itself. :) TIL - CDMA does not have an IMEI... never knew that! Hah! Learnt something there! :)
    – t0mm13b
    Commented Aug 10, 2012 at 0:57
  • 1
    CDMA phones use ESNs instead. The concept is pretty much equivalent, though, so I wouldn't be surprised if the /efs partition will have your ESN on a CDMA device. Commented Aug 10, 2012 at 2:15


Modem's firmware mount point .Store the firmware of the modem same as the modem.bin in the odin tar.md5 flasheable firmware. I see it in Fat16


Stores the wifi and Bluetooth mac adress, some network data , IMEI data (In some samsung phones, not in all models).

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