Section 9.1. Module-Specific Options

9.1. Module-Specific Options

In addition to the options listed in this chapter, parameters for modules that are built in to the kernel can also be passed on the command line. (Dynamically loaded modules, of course, are not in memory when the kernel boots and therefore cannot be passed as parameters at boot time.) The syntax for passing parameters consists of the module name followed by a dot (.) and the parameter.

For example, the usbcore module accepts the parameter blinkenlights to display flashing lights on all supported USB 2.0 hubs (don't ever say the kernel developers don't have a sense of humor). To set this parameter when loading the module dynamically, you would enter:

 $ modprobe usbcore blinkenlights=1 

But if the usbcore module is built into the kernel, you achieve the same effect by invoking the kernel with the following option:

 usbcore.blinkenlights=1 

Most module options for modules that are built into the kernel can also be changed at runtime by writing to files in the subdirectory named after the module under the /sys/module directory. Thus, the blinkenlights option is represented by the file /sys/module/usbcore/blinkenlights.