1.\" $OpenBSD: ahci.4,v 1.7 2008/04/19 01:18:39 djm Exp $ 2.\" 3.\" Copyright (c) 2006 David Gwynne <dlg@openbsd.org> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" TORTIOUS ACTION, ARISING OUT OF 15.\" PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: April 19 2008 $ 18.Dt AHCI 4 19.Os 20.Sh NAME 21.Nm ahci 22.Nd Advanced Host Controller Interface for Serial ATA 23.Sh SYNOPSIS 24.Cd "ahci* at pci?" 25.Cd "ahci* at jmb?" 26.Cd "scsibus* at ahci?" 27.Sh DESCRIPTION 28The 29.Nm 30driver provides support for Serial ATA controllers conforming to the 31Advanced Host Controller Interface specification. 32.Pp 33Several AHCI capable controllers also provide a compatability mode that 34causes them to appear as a traditional ATA controller supported by 35.Xr pciide 4 . 36.Pp 37Although 38.Nm 39controllers are actual ATA controllers, the driver emulates SCSI via a 40translation layer. 41.Pp 42Setting the lowest bit (0x1) of the driver flags forces 43.Nm 44to negotiate SATA 1 (1.5 Gb/s) transfer speeds only. 45It may be useful where higher speeds are unstable. 46.Sh SEE ALSO 47.Xr intro 4 , 48.Xr jmb 4 , 49.Xr pci 4 , 50.Xr pciide 4 , 51.Xr scsi 4 52.Sh HISTORY 53The 54.Nm 55driver first appeared in 56.Ox 4.1 . 57.Sh AUTHORS 58.An -nosplit 59The 60.Nm 61driver was written by 62.An David Gwynne Aq dlg@openbsd.org 63and 64.An Christopher Pascoe Aq pascoe@openbsd.org . 65