RaspberryPi Zero2 W missing kernel modules in repo

Installing and Using OpenWrt
1

Hello all!

Skipping a lot of yapping: im setting up a rpi zero2 w to be used in my car in tandem with a huawei e3772. Wifi was a royal pain in the rear but got it working, what i cant though is the USB lte dongle. The required package “kmod-usb-net-cdc-ether” is missing from the online repos.

Question is how i could make/get the missing package?

(Short story for those interested: car head unit not playing nice with the usb lte modem, and chose the rpiz2w so i can simply power it from the usb of the head unit.)

2

What version of OpenWrt are you running? kmods are kernel-version-specific, so if you're running a snapshot, they are deleted after a few weeks and you'll see symptoms like you're describing.

Your specific kmod is there on a week old snapshot...

$ apk list kmod-usb-net-c*
kmod-usb-net-cdc-eem-6.12.80-r1 x86_64 {feeds/base/kernel/linux} (GPL-2.0-only)
kmod-usb-net-cdc-ether-6.12.80-r1 x86_64 {feeds/base/kernel/linux} (GPL-2.0-only)
kmod-usb-net-cdc-mbim-6.12.80-r1 x86_64 {feeds/base/kernel/linux} (GPL-2.0-only)
kmod-usb-net-cdc-ncm-6.12.80-r1 x86_64 {feeds/base/kernel/linux} (GPL-2.0-only)
kmod-usb-net-cdc-subset-6.12.80-r1 x86_64 {feeds/base/kernel/linux} (GPL-2.0-only)
3

Oh, sorry about that. Looks like im a bit rusty:

/edit

Oh and before i forget, it has no internet because the wifi chip is occupied by acting as AP.

4

The kmod-usb-net-cdc-ether package should be available. I was using exactly the same solution on different OpenWrt versions.

The issue you might be facing is either a lack of access to the repositories, or, if access is available, an incorrect system time on OpenWrt, which breaks package signature verification.

I would suggest the following steps:

On the OpenWrt shell:

  • Stop the Wi-Fi.

  • Reconfigure Wi-Fi to act as a client of your smartphone (using smartphone tethering as temporary internet access during this process).

  • In the Openwrt command line, setup the wifi as a client of the wifi announced by the smartphone.

  • Set DNS to 9.9.9.9 or a similar resolver to ensure name resolution on OpenWrt. Be aware that depending on your setup, OpenWrt may overwrite /etc/resolv.conf, pointing it to 127.0.0.1. So if OpenWrt is failing to resolve domains, check /etc/resolv.conf.

  • Verify that the system date and time are correct on OpenWrt and synchronise it if necessary (you can do this via the UI or NTP).

  • Update package lists (opkg update).

  • Install kmod-usb-net-cdc-ether and any required dependencies.

  • Reboot.

Since no permanent changes are being made to the configuration (only temporary command-line changes), the Pi Zero 2 AP setup should be restored after reboot. Likewise, any temporary changes to /etc/resolv.conf will also be reverted.

From there, you should be able to configure the modem as an Ethernet device. Initially, it should appear in dmesg; you can also check lsusb.

I hope this helps.

5

Be aware that a Raspberry Pi (including the Pi Zero 2) acting as a Wi-Fi access point is a solid and valid solution, but it has a limit on the number of concurrent stations that can connect to it. I can’t remember the exact number, but it is relatively low. When you reach that limit, you may experience random Wi-Fi disconnections without any clear reason. I believe the limit is around 11 to 13 clients, though I can’t recall the exact figure.

6

If the Pi cannot get online while it is acting as the AP, the other clean route is to build the image with that kmod already included. Use the Firmware Selector custom packages field or ImageBuilder and add kmod-usb-net-cdc-ether there. I would avoid copying a kmod from some other build, because the kernel version has to match exactly. After boot, check dmesg/lsusb first so you know whether the dongle is really showing up as cdc_ether or needs mbim/ncm instead.