InformationWeek: Intel Sees A 32-Bit Hole In Itanium

[Anthony Naggs]

In article <20030426094135.GA970 at dhcp01.pn.xcllnt.net>, Marcel Moolenaar
<marcel at xcllnt.net> writes
>On Sat, Apr 26, 2003 at 12:33:34AM -0700, Kris Kennaway wrote:
>> IA-32 Execution Layer will take 32-bit code and convert it to 64-bit
>> code that the Itanium processor can run, an Intel spokeswoman
>> says.
>
>I wonder why the conversion if ia64 can already run ia32 applications.

Quite slow, and Intel need to address AMD64's (perceived) lower risk
migration for x86 users.  AIUI native IA-32 execution doesn't support
instruction extensions introduced on later Pentium models such as SSE,
(since Pentium III).

>Maybe Intel is planning to retire the ia32 execution unit early to
>make room for caches and additional functional units?

The IA-32 support takes little space at the moment, this would change
somewhat if Intel were pushed into including a Xeon with 4 (say) way
Hyper-Threading.  So removing IA-32 wont yield much die space, but it
means Intel don't have to keep taking more space to give IA-32 support
comparable to their higher spec Pentium family.  It also means Intel
aren't committed to including IA-32 execution forever more.

>> Is this something that FreeBSD can/should get involved with?
>
>I think it will be a waste of time. We already have ia32 support
>that we probably don't maintain enough. Something else only adds
>to the workload and it's not that we have people lining up :-)

There is little information about the IA-32 Execution Layer as yet so
one must speculate a little: Intel have committed a lot of development
effort to this, and so wont to let it out of their control (or e.g. to
let Transmeta see the source).  So including IA-32 EL will require
working through Non-Disclosure Agreements and around the need to only
(mostly) have executable code to include in FreeBSD.

Given all that, it seems like a very nice thing to have, (in the same
way as 'Linux compatibility'), and a safeguard against the day Intel
drop native IA-32 from Itaniums.

Writing a translator from IA-32 to reasonably optimized IA-64 would be
quite challenging.  Porting Intel's IA-32 EL should not be too hard,
given the opportunity.

>I think we should allocate our spare resources to work on native
>ia64 and native FreeBSD and make it a kick-ass server. If we get
>bored after that, we can always take on the battle with i386 and
>amd64 by adding compatibility layers and emulation fodder.
>
>Just my $0.02

If anyone has contacts at Intel perhaps they could try to find out if
access to IA-32 EL for porting to FreeBSD would be possible.


Tony