New AMD64 owner

[Brian Tao]

    First time posting to this list, although I've been running
FreeBSD since the 1.1.5.1/2.0 days.  After four years without a decent
workstation at home, I finally took delivery of a dual Opteron 244
Tyan Tiger K8W system.  I've got a few questions that I think I have
the answers to, but wanted to confirm I'm going down the right path,
since this architecture is still pretty new.

    AMD64 CPU's are supposed to have "seamless" backwards
compatibility with 32-bit x86 code... I've confirmed this by watching
Windows 98 boot up on my new system (it was what the integrator had
installed to do some burn-in testing, presumably).  If this is the
case, why am I seeing references to broken ia32 compatibility?
Shouldn't that "just work"?  Or is this a kernel/loader issue with a
64-bit aware install?

    Related to the previous question:  should I be able to install
either freebsd-i386 or freebsd-amd64, and both will work?  Obviously
the i386 install will run in 32-bit mode, but at least it will run
(and act as a really fast Intel box, I'm hoping).  Or is there
something inherent in the kernel or boot process that forces me to run
freebsd-amd64, and cannot utilize the 32-bit compatibility of the CPU?

    The Tyan motherboard has an onboard Silicon Image 3114 S-ATA
adapter.  I have two WD Raptor drives attached.  The aforementioned
Windows 98 appears to boot and recognize the drives just fine (this is
only booting to the command prompt, so there are no third-party
drivers being loaded, AFAICT).  This leads me to believe that the BIOS
or the S-ATA adapter itself is able to dumb itself down to look like a
normal IDE drive.  However, when I tried to boot the 5.2-RELEASE
installer, it was not able to find any drives.  I noticed that Soren
recently committed a change to support the 3114's, but that doesn't
help me if I can't get FreeBSD on the damn disks in the first place.  ;-)

    So I popped over to current.freebsd.org to see if I could grab a
newer ISO (post-Jan 17) with the right SATA drivers.  Latest
successful build is Jan 24, so I'm hoping that will work.  I don't see
an amd64 directory tree there though, which goes back to my earlier
question about doing an i386 binary install on an amd64 platform.  Is
it possible to subsequently do a source build upgrade to amd64?  Or do
we not have the tools to do that yet?

    Thanks for your patience... I'm looking forward to helping improve
freebsd-amd64!
-- 
Brian Tao (BT300, taob at risc.org)
"Though this be madness, yet there is method in't"