On 2007/05/14 11:50, Jeff Simmons wrote:
> Is there any documentation on the exact functions of the flags that can be
> passed to WD via config?
yes, in wd(4), surprisingly enough.
The flags are used only with controllers that support DMA operations and
mode settings (like some pciide(4) controllers). The lowest order
(rightmost) nibble of the flags define the PIO mode to use. The next
four bits indicate the DMA mode and the third nibble 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
UltraDMA, 0xf (1111) means ``disable''. For example, a flags value of
0x0fac (1111 1010 1100) means ``use PIO mode 4, DMA mode 2, disable
UltraDMA''. The special setting 0x0000 means ``use whatever the drive
claims to support''.
