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WD(4)                   NetBSD 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, and EIDE drives.

     The flags are used only with controllers that support DMA operations and
     mode settings (like some pciide controllers).  The lowest order nibble
     (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 occured.  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 sec-
     tor internally, the software bad sector list must be flushed or disabled
     before.

NetBSD 5.2                      August 30, 2004                     NetBSD 5.2