The Advanced Host Controller Interface (AHCI) is an application programming interface defined by Intel which defines the operation of Serial ATA host bus adapters in a non-implementation-specific manner. The specification describes a system memory structure for computer hardware vendors to exchange data between host system memory and attached storage devices. As of June 2008, the current version of the specification is v. 1.3.[1] AHCI gives software developers and hardware designers a standard method for detecting, configuring, and programming SATA/AHCI adapters. AHCI is separate from the SATA 3Gb/s standard, although it exposes SATA's advanced capabilities (such as hot-plugging and native command queuing) such that host systems can utilize them.
Many SATA controllers offer selectable modes of operation: legacy Parallel ATA emulation, standard AHCI mode, or vendor-specific RAID. Intel recommends choosing RAID mode on their motherboards (which also enables AHCI) rather than the plain AHCI/SATA mode for maximum flexibility, due to the issues caused when the mode is switched once an operating system has already been installed.[2] Legacy mode is a software backward-compatibility mechanism intended to allow the SATA controller to run in legacy operating systems which are not SATA-aware or where a driver does not exist to make the operating systems SATA-aware.
AHCI is fully supported out of the box for Windows Vista and Linux operating systems from kernel 2.6.19, as well as later operating systems such as Windows 7. NetBSD also supports drivers in AHCI mode out of the box in certain versions. OpenBSD has had an AHCI driver starting with OpenBSD 4.1. DragonFlyBSD based its AHCI implementation on OpenBSD's and added extended features such as port multiplier support. FreeBSD supports AHCI as well. Solaris 10 introduced AHCI support in the 8/07 release [3]. Older operating systems require hardware-specific drivers to support AHCI.
   | Official webpage - AHCI Specification for Serial ATA |
| | Microsoft Knowledge Base article 922976 - Error message when you start a Windows Vista-based computer after you change the SATA mode of the boot drive: "STOP 0x0000007B INACCESSABLE_BOOT_DEVICE" |
| | SATA optical drives are not available after you start a Windows Vista-based computer - SATA optical drives are not available after you start a Windows Vista-based computer |
| | Intel Matrix Storage Technology - Changing and/or choosing Serial ATA Modes - Intel® Matrix Storage Manager - How to configure the BIOS for RAID or AHCI |
| | an unsupported method to enable AHCI on ICH9 - How to enable AHCI on Intel ICH9 under XP - MSFN Forums |
| | Serial ATA (SATA) Linux hardware/driver status report - Dunvegan Media - Serial ATA (SATA) Linux hardware/driver status report |
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