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mbn_utils

Utilities for Qualcomm mbn file are provided. A mbn file is mainly used to regulate comminucation methods and frequency bands in a cell phone running on a Qualcomm modem. The goal of this tool is to control behaviour of phone's modem by changing the mbn file and flashing into your phone by android fastboot command at your own risk. It is noted that the method to install the modified mbn file into an unlocked device (without root) will be an alternative to get root, open diag port and modify NV items by using QPST. In addition, this tool is inspired by EfsTools.

This tool is under development!

Currently, to change the behaviour by using this tool fails due to mismatch of the digest, which may be related to Qualcomm secure boot. The digest is included in the last item of the main segment, which corresponds to 32 bytes data ranging from index 79 (counts satrting from zero) in the last line of items.txt described below. When a successful match is acheieved in the near future, we can check the digest as /nv/item_files/mcfg/mcfg_sw_config_digest_version in modem EFS by using tools such as QPST. In addition, other digests may be important to make this tool available according to link, and the below table is the summary.

file localtion under image/modem_pr/mcfg/configs of NON-HLOS.bin EFS location
mcfg_sw/generic/(area)/(operator)/Commercial/mcfg_sw.mbn /nv/item_files/mcfg/mcfg_sw_config_digest_version
mcfg_sw/mbn_sw.dig /nv/item_files/mcfg/mcfg_rfs_sw_digest_version
mcfg_hw/mbn_hw.dig /nv/item_files/mcfg/mcfg_rfs_hw_digest_version

How to use

  1. Download this repository and install Ruby
  2. Parse a mbn file to be modified with repack.rb; for instance, the target file named mcfg_sw.mbn is parsed with the following command: 
    ./repack mcfg_sw.mbn
  3. The content of the parsed file is extracted in a directory like mcfg_sw.mbn.extracted.
  4. Edit the content. The most important file is mcfg_sw.mbn.extracted/items.txt, whose each line corresponds to each item of the content with its properties are described in fields separated by commas. The leading field in a line indicates the item type; 1, 2, 4, and 10 are NV, NV_FILE, FILE, and trailer, respectively. The other fields are summarized in the following table. You can not only modify the parsed items but also add or delete the items. If you add or delte files in the extracted directory, items.txt should be updated manually. Especially, do not forget to update the length located at the 7th filed of NV_FILE or FILE after a file item is modified.
    1st field type 2nd 3rd 4th 5th 6th 7th 8th
    1 NV attribute index magic hex byte data separated by spaces
    2 or 4 NV_FILE or FILE attribute file_name stored in the extratced directory magic1 magic2 magic3 length in file offset in file
    10 trailer attribute (N.A.) magic length hex byte data separated by spaces
  5. (Optional) to understand the NV items in items.txt, you can use nv_print.rb to generate human freindly item list: 
    ./nv_print.rb mcfg_sw.mbn.extracted/items.txt
  6. After items.txt and files are modified, rerun repack.rb to get the modified mbn file named as mcfg_sw.mbn.repacked. 
    ./repack mcfg_sw.mbn

Where to get a mbn file

The mbn file is included in a ROM image; for example, image/modem_pr/mcfg/configs/mcfg_sw/generic/(area)/(operator)/Commercial/mcfg_sw.mbn in EFS image named NON-HLOS.bin of a Xiaomi phone fastboot ROM. The content of EFS image is extracted with a LINUX machine by usiang a command like mount -o loop NON-HLOS.bin some_dir.