Recovery Recovery is the reverse process of backup, that is, the backup data stored in FLASH is restored to the corresponding NV item in EFS.
Mentioned before, Qualcomm's NV is stored as a single file in EFS, and the file name of each file is the serial number of the NV item, so we can directly call the read function nv_read of EFS to read The value of a particular NV item. Regarding the software, whether it is to use the final tester, or Qualcomm's QPST, QXDM tools to modify the NV items, the function to write NV will be called at the end: nvdiag_write(), we can create a backup logo file in this function, and click When the secondary system starts, read whether this file exists to determine whether to make a backup. This process will modify some RF-related NV items, which is the NV we need to back up. Generally, a machine must be calibrated and tested with a final tester before leaving the factory. For example, the 10th item NV may have 2 values, 0x11, 0x22, and the format of its storage in FLASH is:Ġa 00 00 00 02 00 00 00 11 22 -(here Item number, The content size is UINT32 type). View Image Each Item is stored in the form of Item number + content size (Byte) + content. The backup area stores data in a certain organizational format (as shown in the figure): Backup area Since there are not many NV items that need to be backed up (usually dozens of items), we can open up an area on FLASH specifically for storing NV backup data. After the creation is successful, the next time you start the computer, it will not be restored. Recovery: Also judge whether there is a recovery logo file in EFS every time you boot up, if it does not exist, restore NV, and then create this logo file. Once the modification to the NV item is detected, a logo file is created in EFS and judged every time it is turned on This marks whether the file exists and whether to perform a backup. Backup: first determine which items of NV need to be backed up (usually RF-related).
Why backup and restore the NV NV value requires calibration and final test to make the mobile phone hardware reach the best working condition, especially the RF-related NV items, after calibration and final test, these NV values of each mobile phone Basically it is different, plus the NV data is stored in EFS, and EFS data is likely to be destroyed (such as: re-programming version), then the NV data will also be destroyed, the previous calibration and final test The subsequent NV data will also not be able to be restored, making the mobile phone face a recalibration and final test production process. For the 60X0 platform, NV has nearly 5,000 items. It is saved in EFS in the form of a single file, but users cannot access it at will, only through QXDM To read and write. Qualcomm platform NV? It saves some parameter values that may be used by each module during system operation. Version 1. platform read and write nv summary Nothing in these materials is an offer to sell any of the components or devices referenced herein. Materials that are as of a specific date, including but not limited to press releases, presentations, blog posts and webcasts, may have been superseded by subsequent events or disclosures.
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