freebsd-skq/share/man/man4/ahci.4

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Separate the parallel scsi knowledge out of the core of the XPT, and modularize it so that new transports can be created. Add a transport for SATA Add a periph+protocol layer for ATA Add a driver for AHCI-compliant hardware. Add a maxio field to CAM so that drivers can advertise their max I/O capability. Modify various drivers so that they are insulated from the value of MAXPHYS. The new ATA/SATA code supports AHCI-compliant hardware, and will override the classic ATA driver if it is loaded as a module at boot time or compiled into the kernel. The stack now support NCQ (tagged queueing) for increased performance on modern SATA drives. It also supports port multipliers. ATA drives are accessed via 'ada' device nodes. ATAPI drives are accessed via 'cd' device nodes. They can all be enumerated and manipulated via camcontrol, just like SCSI drives. SCSI commands are not translated to their ATA equivalents; ATA native commands are used throughout the entire stack, including camcontrol. See the camcontrol manpage for further details. Testing this code may require that you update your fstab, and possibly modify your BIOS to enable AHCI functionality, if available. This code is very experimental at the moment. The userland ABI/API has changed, so applications will need to be recompiled. It may change further in the near future. The 'ada' device name may also change as more infrastructure is completed in this project. The goal is to eventually put all CAM busses and devices until newbus, allowing for interesting topology and management options. Few functional changes will be seen with existing SCSI/SAS/FC drivers, though the userland ABI has still changed. In the future, transports specific modules for SAS and FC may appear in order to better support the topologies and capabilities of these technologies. The modularization of CAM and the addition of the ATA/SATA modules is meant to break CAM out of the mold of being specific to SCSI, letting it grow to be a framework for arbitrary transports and protocols. It also allows drivers to be written to support discrete hardware without jeopardizing the stability of non-related hardware. While only an AHCI driver is provided now, a Silicon Image driver is also in the works. Drivers for ICH1-4, ICH5-6, PIIX, classic IDE, and any other hardware is possible and encouraged. Help with new transports is also encouraged. Submitted by: scottl, mav Approved by: re
2009-07-10 08:18:08 +00:00
.\" Copyright (c) 2009 Alexander Motin <mav@FreeBSD.org>
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.Dd June 26, 2009
.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 loader:
.Bl -ohang
.It Va hint.ahci.X.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.ahcich.X.pm_level
controls SATA interface Power Management for 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.
.El
Note that interface Power Management is not compatible with
device presence detection.
You will have to reset bus manually on device hot-plug.
.It Va hint.ahcich.X.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 CAM 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, 15 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, hardware command queues (up to 32 commands per port),
Native Command Queuing, SATA interface Power Management, device hot-plug
and Message Signaled Interrupts.
.Pp
The Port Multiplier FIS Based Switching feature added in the AHCI 1.2
specification, which is required for effective parallel operation of devices
behind Port Multipliers, is not yet supported.
.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).
.Sh SEE ALSO
.Xr ada 4 ,
.Xr cd 4 ,
.Xr da 4 ,
.Xr sa 4 ,
.Xr scsi 4 ,
.Xr ata 4
.Sh HISTORY
The
.Nm
driver first appeared in
.Fx 8.0 .
.Sh AUTHORS
.An Alexander Motin Aq mav@FreeBSD.org .