[CentOS-devel] Why does CentOS 5 claim to be i386 compatible when it's really not?
martin at rhm.de
Wed Dec 15 10:33:23 UTC 2010
On Tue, 14 Dec 2010 13:29:29 -0500 Jeff Johnson wrote:
> Sure there's an appealing symmetry with "x86" <-> "x86_64". The problem
> is that the names keep changing for marketing and technical reasons.
> Even "i686" and "i586" are mostly meaningless jargon. E.g. the linux
> kernel chose to start returning "i686" as a generic, not specific, and
> rely on precise details in /proc/cpuinfo years and years ago.
This could be because ever since the 1995 introduction of the i686
architecture with the Pentium Pro the core architecture hasn't changed
significantly. AMD's K7 is fully i686 compatible, the K8 is a K7 core
plus 64-bit features, and the K10 is an improved K8. At it's very core
(in terms of instruction set, not in terms of actual silicon
implementation) even the latest Phenom II X6 is still a fully i686
compatible K7. Intel tried a new architecture with the Pentium 4 but
failed spectacularly as we all know, and returned to an improvied i686
processor with its Pentium M (aka Banias), Core and Core 2 series. The
Core i7 is just like the Phenom II - a full i686 instruction set with 64-
Rieke Computersysteme GmbH
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