.\" Copyright (c) 2009 Alexander Motin .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .\" $FreeBSD: src/share/man/man4/ahci.4,v 1.2.2.5.4.1 2010/12/21 17:09:25 kensmith Exp $ .\" .Dd January 28, 2010 .Dt AHCI 4 .Os .Sh NAME .Nm ahci .Nd Serial ATA Advanced Host Controller Interface driver .Sh SYNOPSIS To compile this driver into the kernel, place the following lines in your kernel configuration file: .Bd -ragged -offset indent .Cd "device pci" .Cd "device scbus" .Cd "device ahci" .Ed .Pp Alternatively, to load the driver as a module at boot time, place the following line in .Xr loader.conf 5 : .Bd -literal -offset indent ahci_load="YES" .Ed .Pp The following tunables are settable from the .Xr loader 8 : .Bl -ohang .It Va hint.ahci. Ns Ar X Ns Va .msi controls Message Signaled Interrupts (MSI) usage by the specified controller .Bl -tag -compact .It 0 MSI disabled; .It 1 single MSI vector used, if supported (default); .It 2 multiple MSI vectors used, if supported; .El .It Va hint.ahci. Ns Ar X Ns Va .ccc controls Command Completion Coalescing (CCC) usage by the specified controller. Non-zero value enables CCC and defines maximum time (in ms), request can wait for interrupt, if there are some more requests present on controller queue. CCC reduces number of context switches on systems with many parallel requests, but it can decrease disk performance on some workloads due to additional command latency. .It Va hint.ahcich. Ns Ar X Ns Va .pm_level controls SATA interface Power Management for the specified channel, allowing some power to be saved at the cost of additional command latency. Possible values: .Bl -tag -compact .It 0 interface Power Management is disabled (default); .It 1 device is allowed to initiate PM state change, host is passive; .It 2 host initiates PARTIAL PM state transition every time port becomes idle; .It 3 host initiates SLUMBER PM state transition every time port becomes idle. .It 4 driver initiates PARTIAL PM state transition 1ms after port becomes idle; .It 5 driver initiates SLUMBER PM state transition 125ms after port becomes idle. .El Some controllers, such as ICH8, do not implement modes 2 and 3 with NCQ used. Because of artificial entering latency, performance degradation in modes 4 and 5 is much smaller then in modes 2 and 3. .Pp Note that interface Power Management is not compatible with device presence detection. A manual bus reset is needed on device hot-plug. .It Va hint.ahcich. Ns Ar X Ns Va .sata_rev setting to nonzero value limits maximum SATA revision (speed). Values 1, 2 and 3 are respectively 1.5, 3 and 6Gbps. .El .Sh DESCRIPTION This driver provides the .Xr CAM 4 subsystem with native access to the .Tn SATA ports of AHCI-compatible controllers. Each SATA port found is represented to CAM as a separate bus with one target, or, if HBA supports Port Multipliers, 16 targets. Most of the bus-management details are handled by the SATA-specific transport of CAM. Connected ATA disks are handled by the ATA protocol disk peripheral driver .Xr ada 4 . ATAPI devices are handled by the SCSI protocol peripheral drivers .Xr cd 4 , .Xr da 4 , .Xr sa 4 , etc. .Pp Driver features include support for Serial ATA and ATAPI devices, Port Multipliers (including FIS-based switching, when supported), hardware command queues (up to 32 commands per port), Native Command Queuing, SATA interface Power Management, device hot-plug and Message Signaled Interrupts. .Pp AHCI hardware is also supported by ataahci driver from .Xr ata 4 subsystem. If both drivers are loaded at the same time, this one will be given precedence as the more functional of the two. .Sh HARDWARE The .Nm driver supports AHCI compatible controllers having PCI class 1 (mass storage), subclass 6 (SATA) and programming interface 1 (AHCI). .Pp Also, in cooperation with atamarvell and atajmicron drivers of ata(4), it supports AHCI part of legacy-PATA + AHCI-SATA combined controllers, such as JMicron JMB36x and Marvell 88SX61xx. .Sh SEE ALSO .Xr ada 4 , .Xr ata 4 , .Xr cam 4 , .Xr cd 4 , .Xr da 4 , .Xr sa 4 .Sh HISTORY The .Nm driver first appeared in .Fx 8.0 . .Sh AUTHORS .An Alexander Motin Aq mav@FreeBSD.org .