Draft: modem/rmtfs: add rmtfs-copy-files

Howdy!

This MR causes changes the modem makes to it's partitions actually persist across reboots. They're aren't actually written back to the partitions (this could potentially cause issues with Android), but instead we make a copy of the partitions during boot (if one doesn't already exist) and write back the changes to that.

This might (seriously I have no idea) help with some specific issues people are facing where the modem behaves inconsistently across boots. The EFS partition is a black box for now, and doing a diff before/after the modem writes back it's changes doesn't reveal much (almost every byte has changed, so clearly some encryption/obfuscation).

In addition, this adds a bunch of additional "firmware" files that the modem uses for the OnePlus 6. These contain region/carrier specific configuration data which is associated with VoLTE (and potentially others features?). So far the modem only attempts to read one of these on my device (the high level mcfg_sw.dig file), so these change should be a noop. It should at least make it easier for folks experimenting with VoLTE stuff by having more things be already in the right place.

Unless someone can consistently reproduce an issue and proves that this MR fixes it, we will never know for sure if this helps. But nonetheless I would be really curious to know if anyone who uses pmOS regularly can tell a difference with this MR.

Testing

Hey testing team, please give this a go with mrtest, no special instructions just install the packages applicable to your device and reboot.

• Qualcomm Snapdragon 845/850 (SDM845/SDM850):
  • oneplus-enchilada (@Breakfastisready, @CarbonatedCaffeine, @Susurrus, @antonok, @crowdtier, @panzersajt, @retourmy)
  • oneplus-fajita (@Susurrus, @fdlamotte)
  • shift-axolotl (@Antoniomaciej)
  • xiaomi-beryllium (@anjandev, @panzersajt)