PC begins to function normally. A similar problem can occur on Linux systems if the AHCI driver is compiled as a kernel module rather than built into the kernel image, as it may not be included in the initrd (initial RAM disk) created when the controller is configured to run in Legacy Mode. The solution is either to build a new initrd containing the AHCI module, or to build the AHCI driver into the kernel image. Power management Power management is handled by the Aggressive Link Power Management (ALPM) protocol. See also Open Host Controller Interface (OHCI) Universal Host Controller Interface (UHCI) Enhanced Host Controller Interface (EHCI) Extensible Host Controller Interface (XHCI) Wireless Host Controller Interface (WHCI) Host controller interface (USB, Firewire) References External links "AHCI Specification". Intel. "AHCI". OSDev Wiki Serial ATA