Add Support for EFS/RemoteFS Partitions
qzed opened this issue · comments
Currently, the EFS/RemoteFS partitions are not accessible to us. Due to this we need to use dummy files for the Remote FS service (rmtfs).
On the Lenovo Flex 5G and presumably other SC8180X devices, these partitions can be found on the UFS. Unfortunately, the Pro X does not seem to have a UFS module. The current theory is that they might instead be provided via a QSPI flash. Digging through the Windows drivers should tell us more (e.g. there seems to be a "Qualcomm SoC partition driver", which might fit this).
The Windows remote-fs driver seems to create modem.fs1 and modem.fs2 files in its driver directory. I assume that these are writable copies, which would indicate that the original sources are read-only.
I do no longer believe that a QSPI flash is used directly by the OS. It might be used indirectly somehow maybe by UEFI or some other Qualcomm platform service, however, it looks like if there is a QSPI flash, it's not supposed to be used by the OS directly. There is no indication of it in ACPI and there don't seem to be any drivers for it.
The Windows remote-fs driver seems to create modem.fs1 and modem.fs2 files in its driver directory. I assume that these are writable copies, which would indicate that the original sources are read-only.
They are part of a driver (qcremotefs8180.inf_arm64_8a629fd5db8bab22) and they get copied over like that (bootmodem_fs1 -> /boot/modem_fs1 and bootmodem_fs2 -> /boot/modem_fs2).
I don't know where the other files are fetched from, but it seems like the driver needs them as well (but leaving them empty as we do is fine).
I've tried replacing those files, but I don't see any particular difference. Specifically, my Wi-Fi card is still capped at ~ 11 Mbps despite my regulatory domain is set.
I'll create a new issue specifically to this point (slow Wi-Fi speed), but I don't think it's rmtfs related - although I'm not an expert on this topic.