> What bothers me is maintaining shim drivers which just shuttle opaque > messages between user space and firmware. One of which definitely is, > and the other may well be, proprietary. This is an open source project, > users are supposed to be able to meaningfully change the behavior of > the system. libqmi is an open source library under the LGPL; so all the messages that are passed between e.g. ModemManager and the modem firmware can be easily inspected by anyone. It is true, though, that libqmi may also allow passing "unknown" messages between other proprietary third party applications and the firmware, but that is very much like any other modem control port that we already have; be it a plain tty, or a ttyUSB or a ttyACM or a cdc-wdm port. The kernel drivers are passing unknown stuff between modem firmware and userspace; I don't see how the kernel driver would be interested in any other thing really. QMI and MBIM are just 2 binary protocols (and we have libqmi and libmbim), and there's a generic 3GPP AT command set, but every vendor then has its own interpretation of that AT command set, and vendor-specific AT commands, and what not. From my point of view, it's not like the kernel should know or have much to say on what's being passed to the modem. > > What bothers me is that we have 3 WWAN vendors all doing their own > thing and no common Linux API for WWAN. It may have been fine 10 years > ago, but WWAN is increasingly complex and important. > A WWAN modem is nowadays a complete Linux system itself with tons of features, and if there is sometime a generic WWAN system in the kernel providing API/ABI for generic features (e.g. data connection), that API/ABI should anyway provide access to pass messages (be it binary, or text AT commands) between firmware and userspace, for all the other side features for which no generic API/ABI is provided by that hypothetical generic WWAN system. Unless we don't want any of those side features... like Voice call management, SMS, USSD, GNSS, SAR, OMA-DM, carrier config selection, multi-SIM setups... -- Aleksander
