WD(4)							   BSD Kernel Interfaces Manual 						     WD(4)

NAME

     wd -- WD100x compatible hard disk driver

SYNOPSIS

     wd* at atabus? drive ? flags 0x0000
     wd* at umass?
     options WD_SOFTBADSECT

DESCRIPTION

     The wd driver supports hard disks that emulate the Western Digital WD100x.  This includes standard MFM, RLL, ESDI, IDE, EIDE, and SATA
     drives.

     The flags are used only with controllers that support DMA operations and mode settings (like some pciide controllers).  The lowest order nib-
     ble (rightmost digit) of the flags defines the PIO mode, the next four bits define the DMA mode and the third nibble defines the UltraDMA
     mode.  For each set of four bits, the 3 lower bits define the mode to use and the last bit must be set to 1 for this setting to be used.  For
     DMA and UDMA, 0xf (1111) means 'disable'.	For example, a flags value of 0x0fac (1111 1010 1100) means 'use PIO mode 4, DMA mode 2, disable
     UltraDMA'.  0x0000 means "use whatever the drive claims to support."

     The kernel configuration option ``options WD_SOFTBADSECT'' enables a software managed bad-sector list which will prevent further accesses to
     sectors where an unrecoverable read error occurred.  A user interface is provided by dkctl(8).  Unlike the (historical) mechanisms provided
     by bad144(8) and badsect(8) the software list does neither support sector replacement nor is it saved across reboots.

SEE ALSO

     ata(4), intro(4), pciide(4), scsi(4), umass(4), wdc(4), atactl(8), dkctl(8)

BUGS

     The optional software bad sector list does not interoperate well with sector remapping features of modern disks.  To let the disk remap a
     sector internally, the software bad sector list must be flushed or disabled before.

BSD
								  August 30, 2004							       BSD