Now I am trying to recompile the kernel without the offending builtin driver. I'm using yocto, but I don't know what the best way is to figure out exactly where that driver is coming from, and remove it from the build.

Before trying to rebuild the kernel, I installed a new version of the driver as a loadable module, but was unable to load and bind the device to it because the builtin module had taken the name asix already.

I tried recompiling the driver with a new name asix_new and using a udev rule to disconnect the relevant device from the old builtin asix driver and connecting it to the axix_new loadable driver. This didn't work for more hazy reasons. My best guess is that the device didn't like being disconnected, but I can't tell for sure.

I am following the instructions on the docs to rebuild and flash the kernel to the VOXL 2.

I have also tried using:

$ bitbake linux-msm -c menuconfig
$ bitbake linux-msm -c diffconfig

then deselecting what I believe are the only two USB ethernet dongle drivers from Asix (CONFIG_USB_NET_AX8817X and CONFIG_USB_NET_AX88179_17A), moving the resulting .cfg file into meta-voxl2-bsp/recipes-kernel/linux-msm/files/fragments/ then adding that file to the meta-voxl2-bsp/recipes-kernel/linux-msm/linux-msm_4.19.bbappend file as described in the yocto docs. But when I rebuild the project and flash it to the board, I still get the error that asix is builtin:

$ modprobe -r asix    
modprobe: FATAL: Module asix is builtin.

I'll also add that modinfo provides no information here:

$ modinfo asix
modinfo: ERROR: Module asix not found.