Where are kernel modules installed? I am trying to find Linux kernel modules on my nitrogen board.
I have unpacked kernel config from /proc/config.gz and I see kernel was compiled with a lot of modules.
I see only one in /vendor/lib/modules, zero in /system/lib/modules.
Can somebody explain where modules installed, what is procedure to install modules?
There are two ways Linux kernel modules are built: 1. as a part of kernel executable binary (compressed image) i.e. with CONFIG_*=y options at build time, or 2. as separate kernel object (.ko) files that can be loaded and unloaded with some conditions i.e. built with CONFIG_*=m options.
In second case the .ko files are placed on some standard location(s), usually /lib/modules/ on Linux and its equivalent on Android /system/lib/modules/ or /vendor/lib/modules/. These paths are hard-coded in binaries that load them e.g. insmod, modprobe.

On pre-Pie releases (1), by-default Android kernel is built without option CONFIG_MODULES=y, so there are no kernel modules built as .ko files which can be loaded or unloaded with insmod, modprobe or rmmod as is the case with standard Linux distros. Nor they are exposed through /proc/modules from where lsmod reads information. However each kernel component that can be built as a module has an entry in /sys/module.  

Now those modules which are compiled and loaded as .ko file has a corresponding /sys/module/&lt;module&gt;/initstate file, others don't have. You can confirm this way if there are any loaded modules:

~$ ls /sys/module/*/initstate