New AMD64 owner

[David O'Brien]

On Thu, Jan 29, 2004 at 09:10:35AM -0600, James Van Artsdalen wrote:
> The AMD64 processors start up in an Intel x86 compatible mode.
> If nobody puts it in 64-bit mode then it will stay x86 compatible.

Not quite, unless you call the Intel i386 (and Pentium's) as x86
compatible.  All this is simply operating modes: 16-bit real mode,
32-bit real mode (used by the BIOS), 32-bit protected mode; and now added
to the list is 64-bit protected mode.


> Yes, either work, and as an x86 it is as fast as any Intel x86.

Faster.  8-)
 
> A lot of AMD64 architecture tradeoffs are best understood by realizing
> that AMD64 is focused squarely on Intel's 32-bit market, with any
> 64-bit/server wins icing on the cake but not the site of the real
> battle for a profit.

Not quite -- AMD definitely wants to penetrate the 64-bit data center
market.  BUT, AMD isn't walking away from the markets Athlon already
plays in.

> Nowhere that I know of has AMD sacrificed 32-bit
> functionality or performance to get even one iota of 64-bit advantage.

Correct.


> Win9x is probably booting in compatibility mode.  There is some magic
> called the Real Mode Mapper that switches the processor back to real
> mode, does BIOS calls in real mode, and then switches back to
> protected mode.  In any case, testing Win9x in this way doesn't really
> tell you anything about a disk controller with an option ROM unless
> you look carefully to see how Win9x is accessing the drive.

Correct.  If you try to install MS-Win64, you'd have to go find an Si3114
driver.  Win 9x "cheats" as it is still a 16-bit OS that can do BIOS
calls at the very lowest core.


> I think Peter has said he has no plans to try to do an upgrade-in-place
> from a 32-bit to 64-bit FreeBSD environment.

It all depends on what someone commits to the 'make world' mechanism.  It
is all of our choice to make this work as is anything else in
FreeBSD'ville.  The question is who has the "itch" and will spend the
effort to "scratch" it.

-- 
-- David  (obrien at FreeBSD.org)