http://mail-index.netbsd.org/tech-kern/2003/09/25/0006.html
This adds a device (atabus) between IDE controllers and wd or atapibus, to
have each ATA channel show up in the device tree. Later there will be atabus
devices in /dev, so that we can do IOCTL on them.
Each atabus has its own kernel thread, to handle operations that needs polling,
e.g. reset and others.
Device probing on each bus it defered to the atabus thread creation.
This allows to do the reset and basic device probes in parallel, which reduce
boot time on systems with several pciide controllers.
Such RAID controllers are actually just IDE controllers with a BIOS that
can create RAID volumes and write the configuration info to config blocks
on the disks. The BIOS can do I/O to these volumes, and the OS must
understand the config blocks and implement RAID in software in order to be
able to use these volumes.
Only SPAN (simple concatenation) and RAID0 are supported at this time,
and writing back config blocks is also not supported at this time. Currently,
only the Promise configuration scheme is supported, although supporting
the Highpoint scheme should not be too difficult.
In any case, this is sufficient to use the Promise RAID0 volume (thus
preserving the win2k AS installation) on this new Intel server I have.
Thanks to Soren Schmidt for doing the work in FreeBSD; it made this
task much easier. The config block parsing code is adapted from his
work.
now lives in dev/ic, wd now lives in dev/ata. there's now a 'ata'
interface attribute defined in conf/files, but wdc can't go there
yet because some ports still use private versions based on the old
ISA version.
bouyer