modules.dep
also: modules.dep.bin, dependency file
A kernel configuration file that maps module dependencies, telling modprobe which kernel modules must be loaded before others. It's automatically generated by depmod and read by the module loader.
modules.dep is a dependency map file located in /lib/modules/$(uname -r)/ that lists which kernel modules depend on other modules. When you try to load a module, the system consults this file to automatically load any required dependencies first.
The file is generated by the depmod command, which scans all compiled kernel modules and analyzes their symbol requirements. Each line lists a module followed by its dependencies. For example: kernel/drivers/usb/host/xhci-pci.ko: kernel/drivers/usb/host/xhci-hcd.ko
Without modules.dep, tools like modprobe wouldn't know which modules to load automatically, and you'd have to manually load dependencies in the correct order using insmod. The file is typically regenerated when kernels are updated or modules are rebuilt.