[CentOS-devel] Re: CentOS-5 on i586

[Scott Silva]

on 4-7-2008 11:06 AM Manuel Tuthill spake the following:
>> It looks like the Geode is i586 but with cmov functionality.
>>
>> It strikes me as odd that AMD would build a 586 processor with cmov
>> instructions, but also build a 686 class without that instruction set.
>> Makes
>> me wonder if it was an engineering snafu that was too costly to fix for
>> the
>> quantity they expected to sell.
> 
> 
> Wow, that seems very odd. cmov was only part of the i686 instruction set so
> this still wouldn't work with a native i686 distribution right?
> 
> BTW it was VIA not AMD who made the "engineering snafu" on the VIA C3 class
> chips. Rather than being a "snafu" they interpreted the IA32 specifications
> a little to literary, the CMOV is an optional instruction, but as fair as I
> understand if it's optional it shouldn't be used at all (since there is no
> guarantee that it will be available to all i686 cpu's) but since every other
> i686 class cpu had the instruction when they were doing GCC it got left.

I totally forgot the timeline. VIA did make these chips long before the AMD 
buyout.

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