We make backup EFS / IMEI:
1 - download nexus_4_backup_efs.zip;
2 - put it on the phone;
3 - boot into CWM / TWRP recovery;
4 - flashing this zip (no need to do wipes, just boot into the system);
5 - a zip will be created (efsbackupflashable.zip) in the same place where your recovery file stores a backup (for cwm this is data / media / EFS_Backup; for twpr - in / SDCARD / EFS_Backup);
6 is a backup of three blocks (M9KEFS1.img, M9kefs2.img, M9kefs3.img) in the format of RAW images (each 780 KB);
7 - Save this folder on your computer, in the cloud (for greater security).
for those,
Who has a file system in ext4(stock and most customs);
for those,
Who has a file system in F2FS.
Restore EFS / IMEI from backup:
Sew this backup from CWM / TWRP.
If you lost the zip firmware, you can restore efs img from
adb shellor
Android Terminal Emulator:
if used CWM
DD if = / Data / Media / EFS_BACKUP / M9KEFS1.img of = / dev / block / mmcblk0p8
DD if = / data / media / efs_backup / m9kefs2.img of = / dev / block / mmcblk0p9
DD If = / Data / Media / EFS_BACKUP / M9KEFS3.img of = / dev / block / mmcblk0p10
and if done through TWRP
DD if = / sdcard / efs_backup / m9kefs1.img of = / dev / block / mmcblk0p8
dd if = / sdcard / efs_backup / m9kefs2.img of = / dev / block / mmcblk0p9
dd if = / sdcard / efs_backup / m9kefs3.img of = / dev / block / mmcblk0p10
Attention: this backup is unique (only for the device on which it was made)! Do not try to flash backup from another phone!topic on
XDA.
Why do I need a backup EFS / IMEI
Each phone has a section containing data related to your IMEI, radio settings, data profiles, etc. .. This, in particular, is famous for the Samsung devices that have root / efs and which are very recommended to create a backup copy before the firmware of any custom firmware . However, there is a common misconception that there is no EFS section for Nexus, as there is no this folder and everything is contained in common dev / blocks. On Nexus 4 IMEI information is stored in three M9KEFS1 blocks (/ dev / block / mmcblk0p8) M9KEFS2 (/ dev / block / mmcblk0p9) M9KEFS3 (/ dev / block / mmcblk0p10). These blocks contain all IMEI information related to the phone. They are unique for each device, which means: Each device has a different data in each block, in contrast to the blocks for recovery, loading, which are common to all. Since the EFS / IMEI of your device is unique, therefore you need to make a backup of your EFS.
Why make backup EFS?
1) Some points were explained above (unique for each device, important data).
2) Sometimes during the firmware or simply when used, a bad block appears in a section that breaks part of the EFS / IMEI section and then you will remain without mobile communication. Then you need to return to the radio version 0.27 (this radio seems magical, as it is still able to read damaged data) and Android 4.2. 2.
Post has been editedDemotion - 28.11.14, 19:33