Librem 5 - LTE Bands support for US


#22

What about this modem ? Would this work ? https://www.sierrawireless.com/products-and-solutions/embedded-solutions/products/em7455/

And it seems to be registered with US carriers too

50 bucks on amazon and made in vietnam


#23

The Quectel EM06 would have been my preferred modem choice but I guess some off brand Chinese junk will have to do for now. The Quectel EM06 would carry the US certifications assuming they finish development.


#24

As much as Gemalto can sub for Gemalto (PLS8-E or US), one cannot mix Gemalto and Broadmi. Former is MBIM and latter (Broadmi) is QMI. The use of Gmobi is required for the first and needs removal for wwan to be enabled and functional for QMI Qualcomm service function.
MBIM is general modem used and QMI is neweer standard, the two incompatible to load to one system. See: https://openwrt.org/docs/guide-user/network/wan/wwan/ltedonglehttps://openwrt.org/docs/guide-user/network/wan/wwan/ltedongle


#25

soooo how are both an option then?


#26

Not sure if you understood what I said. They will offer one of these 2 to be shipped with - not both.
And I also don’t understand what do you mean by “incompatible”. Are you talking about having them work - installed at the same time ?


#27

Two different libraries (incompatible to load to one system) for talking to WWAN modems and devices on Debian Linux:

  1. Mobile Broadband Interface Model (MBIM) specification from Microsoft = libmbim-glib4/libmbim-proxy
  2. Qualcomm MSM Interface (QMI) protocol = libqmi-glib5/libqmi-proxy

Meaning you do not need to have both of them installed, as I understood above intention, but certainly appropriate ones that belong to either Gemalto or BroadMobi modem. It is quite simple and useful (good to know) remark from @MJKPJ1050.


#28

Of course Makes sense. I don’t think that anyone here was implying or trying to have 2 of these modems used at the same time.


#29

I did not make myself clear, for which I am sorry.
If only a single modem is utilized, it may be reasonable to know that a simple hardware swap may be insufficient should the Librem 5 owner seek to go from a MBIM to a QMI modem or to make the change in the opposite direction. Without altering the software of the Linux subsystem, the modem will be inoperable. Merely adding wwam to the system is insufficient as the modem address system previously used, mgobi, needs removal for QMI and the opposite for the alternative direction.
More problematic, jockeying between 2 M.2cards is likely to be easy only if MBIM to MBIM or QMI to QMI as all sorts of software defaults may be problematic with frequent interchange of software systems for competing standards is required for alternating modem standard selection in operation.


#30

Please don’t confuse people. It is pretty standard for Linux to include drivers for basically all supported hardware. The appropriate driver, and with it the protocol used by the device, is selected automatically.
Should there be any additional per device settings, somebody will think of a way to save them per device.


#31

Yes, thank you. But even if this issue is for some of us self-explanatory we could still have people here that are coming from Microsoft Windows world and try to understand how this works within Linux. Anyway, I like to be self-confused but not ignorant to other people concerns (within this community).


#32

I do not address drivers here. Rather, I am addressing modem protocol rules which perhaps, if I am mistaken in the matter, I may owe apology. I would request that you read the following and perhaps you can tell me where I may have gone off track: https://gist.github.com/Juul/e42c5b6ec71ce11923526b36d3f1cb2c


#33

I would note that the protocols have differing library packages that need to be installed for MBIM or for QMI modems respectively. It may well be possible that the libraries can be kept side by side without need to uninstall, but the protocols have, at the minimum, if I am correct, to be inactivated by commenting out their usage in some modem initiation file should incompatible modems be alternated.


#35

From what I recall, in a private convo the rep told me that switching them should be easy as pie. I think they figured that out.


#36

Well, QMI is not newer as you say, but Qualcomm specific per your document. As none of the modems offered are by Qualcomm, I’d assume all are using MBIM. But even if a modem would support both and you select a mode unsupported by a different device, that other device should be unaffected, as the protocol preference is either the responsibility of the driver or the firmware, which are different for different devices.
Just because a DIY guide on the topic explains how to change stuff when you build you own thing should not lead you to assume that you need to manually configure stuff on a ready made product that you pay for to just work.
Now, not everything will work day one, but this doesn’t seem to be one of those things.


#37

Though extremely difficult to find, I request that you seek out this webpage for the BM818 manual:
https://fccid.io/2AON8-BM818/Users-Manual/BM818-Coperation-manual-V1-4-4107101.
Even here there is no clear documentation of the QMI.
HOWEVER if you go to:
https://lkml.org/lkml/2019/7/24/605
There you will see that the site says: “The BroadMobi BM818 M.2 card uses the QMI protocol”.
Broadmi is likely licensing an older Qualcomm chip.
The situation of problems only accrues if going from a different manufacturer, such as the MBIM device of Gemalto and seek to swap it for the BMI without a reload. Please do note this is not that I know, but what I can ‘dope out’ from the meager literature that I have at hand.


#38

Given other literature that I have seen with Angus’ name, I suspect that lkml.org is part of Librem and that this is some now possibly publicized semi-internal document that I managed to find.


#39

Again, physical swap out is fine. Perhaps software libraries and protocols do not matter. See my reply to Caligra and the site I noted for him: The BroadMobi BM818 M.2 card uses the QMI protocol


#40

Please see: https://lkml.org/lkml/2019/7/24/605 should this message not be hidden/censored or labelled spam, whichever the story may be.


#41

I thank you for your open mind. My concern is rapid swapping if someone commutes between Europe and US and expects differing modem standards to work without re-configuring them. Simply expecting M.2 card to function akin to Plug and Play may be incorrect. Broadmi BM818 is QMI (https://lkml.org/lkml/2019/7/24/605) while the Gemalto is MBIM and the two have differing libraries and protocols. I have read that MBIM protocol needs removal or at least inactivation for QMI to work properly.
I will admit that I am no expert here and perhaps even misled, but my intention is honest.


#42

This is what allows Linux to boot and run entirely from a USB. Distros are developer just for that purpose.