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acd (4)
>> acd (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
ataaracdadafdast
- generic ATA/ATAPI disk controller driver
SYNOPSIS
For ISA based ATA/ATAPI support:
device isadevice ata
In
/boot/device.hints
hint.ata.0.at=isahint.ata.0.port=0x1f0hint.ata.0.irq=14hint.ata.1.at=isahint.ata.1.port=0x170hint.ata.1.irq=15
For PC98 based ATA/ATAPI support:
device isadevice ata
In
/boot/device.hints
hint.atacbus.0.at=isahint.atacbus.0.port=0x640hint.atacbus.0.irq=9
For PCI based ATA/ATAPI support:
device pcidevice ata
To support ATA compliant disk drives:
device atadisk
To support ATA software RAID's:
device ataraid
To support ATAPI CDROM, DVD and CD/DVD burner drives:
device atapicd
To support ATAPI floppy drives:
device atapifd
To support ATAPI tape drives:
device atapist
The following tunables are settable from the loader:
hw.ata.ata_dma
set to 1 for DMA access, 0 for PIO (default is DMA).
hw.ata.ata_dma_check_80pin
set to 0 to disable the 80pin cable check (default is 1, check the cable)
hw.ata.atapi_dma
set to 1 for DMA access, 0 for PIO (default is DMA).
hw.ata.wc
set to 1 to enable Write Caching, 0 to disable (default is enabled).
WARNING
can cause data loss on power failures and crashes.
DESCRIPTION
The
driver provides access to ATA (IDE) and SerialATA disk drives,
ATAPI CDROM/DVD drives, ZIP/LS120 ATAPI drives and ATAPI tape drives
connected to controllers according to the ATA/ATAPI standards.
The currently supported ATA/SATA controller chips are:
Unknown ATA chipsets are supported in PIO modes, and if the standard
busmaster DMA registers are present and contain valid setup, DMA is
also enabled, although the max mode is limited to UDMA33, as it is
not known what the chipset can do and how to program it.
The
driver can change the transfer mode and various other parameters
when the system is up and running.
See
atacontrol(8).
The
driver sets the maximum transfer mode supported by the hardware as default.
However the
driver sometimes warns:
``DMA limited to UDMA33, non-ATA66 cable or device.
''
This means that
the
driver has detected that the required 80 conductor cable is not present
or could not be detected properly,
or that one of the devices on the channel only accepts up
to UDMA2/ATA33.
The
hw.ata.ata_dma_check_80pin
tunable can be set to 0 to disable this check.
Unknown ATAPI devices are initialized to DMA mode if the
hw.ata.atapi_dma
tunable is set to 1 and they support at least UDMA33 transfers.
Otherwise they are set to PIO mode because severe DMA problems are
common even if the device capabilities indicate support.
You can always try to set DMA mode on an ATAPI device using
atacontrol(8),
but be aware that your hardware might
not
support it and can potentially
hang
the entire system causing data loss.
FILES
/dev/ad*
ATA disk device nodes
/dev/ar*
ATA RAID device nodes
/dev/acd*
ATAPI CD-ROM device nodes
/dev/afd*
ATAPI floppy drive device nodes
/dev/ast*
ATAPI tape drive device nodes
/sys/i386/conf/GENERIC
sample generic kernel config file for
based systems
NOTES
Please remember that in order to use UDMA4/ATA66 and above modes you
must
use 80 conductor cables.
Please assure that ribbon cables are no longer than 45cm.
In case of rounded ATA cables, the length depends on the
quality of the cables.
SATA cables can be up to 1m long according to the specification.
Static device numbering
(enabled with the
ATA_STATIC_ID
kernel option)
reserves a number for each possibly connected disk,
even when not present.
This is useful in hotswap scenarios
where disks should always show up as the same numbered device,
and not depend on attach order.
Native Command Queuing (NCQ) on SATA drives is not yet supported.