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Re: x86-64 on i386 (was Re: Promoting i386 version over x86_64?)



On 12/14/2009 01:56 AM, Jon Masters wrote:
On Sun, 2009-12-13 at 16:19 -0600, Chris Adams wrote:
Once upon a time, Jon Masters<jonathan jonmasters org>  said:
Indeed. Paul, take a look at the Intel 64 ISA and you'll see it's a very
different beast. Intel fixed a lot of the issues with the (more than 20
year old really x86 ISA)

That would be AMD that fixed it, not Intel.  Intel tried to push
everybody to a new architecture (Itanium), while AMD revised and
extended i386 to 64 bits.  After Itanium failed to catch on in the
marketplace, Intel had to copy AMD's work.

That's presumptuous and unfair. Sure, without AMD and others we'd likely
be on Itanium (which I actually quite like as an architecture) but Intel
64 isn't just some copy-and-paste effort either.

I thought Intel adopted AMD 64-bit extensions pretty much wholesale. No shame in that---they were well-designed and well engineered. We the CPU consumers should be thankful for how well this was executed by both Intel and AMD. Kudos to Intel for acting in the best interest of their customers especially since they had so much invested in Itanium, both financially and in term of company pride.

While Itanium (aka Itanic :) was well-intentioned and looked good on paper, Intel/HP run into practical problems with the extent to which VLIW can be exploited by compilers, and with the hardware implementations, so that the actual performance is underwhelming. The Itanium siren song contributed to demise of SGI and wobbliness of HP so let's not be too nostalgic about it.


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