I've been working with hard drive diagnostic test developement under
DOS/Windows environment for past years.   Currenlty, I am try to do the same
operations under FreeBSD.  I've been searching under web, found a lot of
info.   I also look at the source code directory for ATA (ata-all.h
ata-all.c ata-disk.c ata-disk.h, etc...)  But I don't seem to be able to put
the puzzle together.   If you can have sometimes and point me to right
directory.  The operations I am try to do is be able talk directly to
ide/scsi hard drive (ide mainly) so that I can issue ATA commands, get SMART
attributes, drive vendor, firmware version, cycliner, head, sector, read,
write, seek sector off the hard drive.   I find a code of atactl.c.   It
used opendisk (only in NetBSD and OpenBS), I cannot figure out how to use it
under FreeBSD.    This function will open drive and return a handle.   This
will be helpful if I can get a handle of drive under FreeBSD.    Also, under
kernel source code ATA.   Are there anyway I can use some of code to create
tools or utility.   I can seem to get around #include <sys/systm.h>
statement.  And the header file for "opt_global.h" "opt_ata.h" is defining
at top of file, I dont understand where these two files come from.  It must
be build during compile kernel.  Always, report errors.   The ata
directory's source are all kernel ata driver.   I really like to know to use
those function and can access hard drive directory like the kernel ata
driver. 

Thanks in advance
sonny