i386/x86_64 segment register issuses

Ross Ridge rridge@csclub.uwaterloo.ca
Wed Mar 30 16:37:00 GMT 2005


> Given that it is specified for x86_64, it will be very strange that
> the future Intel ia32 processors are different from the future Intel
> x86_64 processors in this regard.

Regardless of what you might believe to be strange, the guarantee you're
assuming you have does not in fact exist.

> As for non-Intel processors, they aren't Pentium Pro compatible if
>they are different.

Even Intel doesn't claim any of its processors are Pentium Pro compatable.

Like it or not, the fact is that if a register operand is the destination
of a segment register move instruction then the value placed in the
upper 16-bit of registers is architecturally undefined.

						Ross Ridge

-- 
 l/  //	  Ross Ridge -- The Great HTMU
[oo][oo]  rridge@csclub.uwaterloo.ca
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