J710f | Efs File

The /efs partition contains that are written once during manufacturing. Without a valid EFS, the device becomes a "network island"—unable to register on any cellular network, losing IMEI, baseband version, and Bluetooth/Wi-Fi MAC addresses. 2. Critical Contents of /efs (SM-J710F) | File/Directory | Purpose | |----------------|---------| | /efs/imei/imei | Binary file storing the device's 15-digit IMEI (and second IMEI for dual-SIM J710F/DS). | | /efs/imei/mps_code.dat | Sales/product code (e.g., INU, XME, INS) for region-specific CSC behavior. | | /efs/wifi/.mac.info | Wi-Fi MAC address in plaintext. | | /efs/bluetooth/bt_addr | Bluetooth MAC address. | | /efs/nv_data.bin | Most important file —encrypted binary blob containing RF calibration parameters, NV items (like QCN on Qualcomm), and IMEI checksums. | | /efs/nv_data.bin.md5 | MD5 hash of nv_data.bin used for integrity verification. | | /efs/FactoryApp/factorymode | Flag indicating whether factory mode is active (can affect network locks). | | /efs/FactoryApp/serial_no | Device serial number. | | /efs/carrier/ | Operator-specific configuration (e.g., hidden menus, APN overrides). |

1. What is the EFS Partition? The EFS (Encrypted File System) is a dedicated partition found on Samsung Exynos and Qualcomm Snapdragon devices, including the SM-J710F (which uses the Exynos 7870 SoC). It is not part of the user data partition ( /data ) or system partition ( /system ). Instead, it exists as a separate logical volume—typically /dev/block/mmcblk0p13 or similar (exact index varies by firmware version). j710f efs file