The Advanced Host Controller Interface (AHCI) is a hardware mechanism that allows software to communicate with Serial ATA (SATA) devices such as host bus adapters which are designed to offer features not offered by Parallel ATA (PATA) controllers besides higher speeds, such as hot-plugging and native command queuing. The specification details a system memory structure for computer hardware vendors in order to transfer data between system memory and the device. The current version of the specification is, as of July 2007, v1.2.^[1] SATA redirects here. ... ATA connector on the left, with two motherboard ATA connectors on the right. ... Hot swapping or hot plugging is the ability to remove and replace components of a machine, usually a computer, while it is operating. ... Native Command Queuing (NCQ) is a technology designed to increase performance of SATA hard disks by allowing the individual hard disk to receive more than one I/O request at a time and dynamically change the order in which they are applied. ...

Many SATA controllers can enable AHCI either separately or in conjunction with RAID support. Intel recommends choosing the RAID mode (which also enables AHCI) on their motherboards rather than the AHCI/SATA mode.^[2] For other uses, see Raid. ... A motherboard is the central or primary circuit board making up a complex electronic system, such as a modern computer. ...

AHCI is fully supported in Microsoft Windows Vista and the Linux operating system from kernel 2.6.19. Support for AHCI is also featured in Windows XP Media Center Edition (the only version of XP to support it), prompting many manufacturers to ship with this version despite the hardware not supporting the multimedia features of this version (an example being the Dell Dimension 5150C). Older operating systems require drivers written by the host bus adapter vendor in order to support AHCI. Windows Vista is a line of graphical operating systems used on personal computers, including home and business desktops, notebook computers, Tablet PCs, and media centers. ... This article is about operating systems that use the Linux kernel. ... An operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources. ... The Linux kernel is a Unix-like operating system kernel. ... A typical Windows XP MCE 2005 Menu Windows XP Media Center Edition (MCE) is a version of Windows XP designed to serve as a home-entertainment hub. ... This article is about the corporation Dell, Inc. ...

Common problems switching to AHCI under Windows

• Enabling AHCI in a system BIOS will cause a 0x7B Blue Screen of Death STOP error (INACCESSIBLE_BOOT_DEVICE) on installations of Windows XP where AHCI/RAID drivers for that system's chipset are not installed. Switching to AHCI mode requires installing new drivers before changing the BIOS settings.
• When attempting to install Microsoft Windows XP or a previous version on an AHCI-enabled system will cause the setup to fail with the error message "set up could not detect hard disk drive...". This problem can only be corrected by either using a floppy disk with the appropriate drivers, by slipstreaming the appropriate drivers into the Windows XP installation CD or by turning on IDE emulation in the BIOS settings if available.
• Enabling AHCI in a system BIOS with Windows Vista already installed will result in a BSoD if SATA has been running in IDE mode during Vista's installation. Before enabling AHCI in the BIOS, users must first follow the instructions found at Microsoft Knowledge Base article 922976.
• Enabling AHCI in a system BIOS on installations of Windows XP or Windows Vista, will cause SATA Optical drives to disappear. A Hotfix for Windows Vista is available under the title: "SATA optical drives are not available after you start a Windows Vista-based computer."^[3]

For other uses, see Bios. ... A blue screen of death as seen in Windows XP and Vista. ... Windows XP is a line of operating systems developed by Microsoft for use on general-purpose computer systems, including home and business desktops, notebook computers, and media centers. ... A floppy disk is a data storage device that is composed of a disk of thin, flexible (floppy) magnetic storage medium encased in a square or rectangular plastic shell. ... In computer slang, to slipstream is to integrate files from a hotfix or service pack into the original installation media. ... Windows Vista is a line of graphical operating systems used on personal computers, including home and business desktops, notebook computers, Tablet PCs, and media centers. ... A blue screen of death as seen in Windows XP and Vista. ...

Common problems switching to AHCI under Linux

• AHCI controller does not work on AMD/ATI RS400-200 and RS480 HBA when MSI is enabled due to a hardware error. In order for AHCI to work users must provide the "pci=nomsi" kernel boot parameter. With MSI disabled in this way, the PCIe bus can only act as a faster PCI bus with hotplug capabilities. This is also true of the Nvidia nForce 560 chipset.
• AHCI controller on AMD/ATI SB600 HBA can't do 64bit DMA transfers. 64-bit addressing is optional in AHCI 1.1 and the chip claims it can do them, but in reality it can't, so it is disabled. After that it will be forced to do 32bit DMA transfers. Thus DMA transfers will occur at the lower 4GB region of the memory, and bounce buffers must be used sometimes if there is more than 4GB of RAM.

Message Signaled Interrupts, in PCI 2. ...

External links

• Official webpage
• Version 1.2 specification

References