The sysfs filesystem is a virtual filesystem that the kernel uses to export internal kernel objects, their attributes, and their relationships to one another. Users can use sysfs to ascertain useful information about the running kernel, such as the devices the kernel has discovered on each bus and which driver each is bound to. sysfs can also be used to tune devices and other kernel subsystems. Some system agents rely on the information in sysfs to operate. /sbin/hotplug uses device and object attributes in sysfs to assist in delegating policy decisions, like persistently naming devices. sysfs is currently used by the block subsystem to mount the root partition. If sysfs is disabled you must specify the boot device on the kernel boot command line via its major and minor numbers. For example, "root=03:01" for /dev/hda1. Designers of embedded systems may wish to say N here to conserve space.