A signature error occurred "module verification failed: signature and/or required key missing - tainting kernel"
Module signature verification is a kernel feature, which needs to be enabled through the Linux kernel compilation.
Solution 1: When compiling the kernel, add CONFIG_MODULE_SIG=n.
Solution 2: Sign the kernel module with the certificate, as shown below:
/usr/src/linux-4.9.61/scripts/sign-file sha512/usr/src/linux-4.9.61/certs/signing_key.pem /usr/src/linux-4.9.61/certs/signing_key.x509 toa.ko
The /lib/modules directory is missing during compilation
This error is often associated with the following situations:
The kernel package is not installed.
When the directory is modified, you need to correct it by yourself.
When the kernel does not have the build directory, you need to manually create a soft link to the exact version of the kernel header.
cd /lib/modules/4.9.0-13-amd64 && ln -s /usr/src/linux-headers-4.9.0-13-amd64 build