[Mageia-dev] i686 must be Pentium II ?

Sun Sep 26 13:05:18 CEST 2010

Giuseppe Ghibò skrev 26.9.2010 02:09:
+
+> Not exactly. I'm not talking in just using -march=<something> but in
+> also pushing -mfpmath=sse -msse (and maybe -msse2) , which should be
+> much more than JUST 1-2% (1-2% is usually the benchmark
+> tolerance)...
+
+Well, here is a simple fact.
+
+Yes, going for i686 + SSE2 would/could give some benefits,
+
+BUT
+
+It would close support for all theese:
+- Intel i586 (all)
+- Intel Pentium Pro
+- Intel Pentium II
+- Intel Pentium III (Including some Pentium D)
+- 32-bit AMD Athlon
+- AMD Geode
+- VIA C3
+- Transmeta Crusoe
+
+So, thats not an option.
+
+
+Now what about only i686 + SSE then?
+It would still close support for all theese:
+- Intel i586 (all)
+- Some Intel Pentium D
+- 32-bit AMD Athlon < XP/MP
+- AMD Geode < NX
+- VIA C3 (Samuel* and Ezra)
+- Transmeta Crusoe
+
+So, still not an option.
+
+
+Now what about only i686 then?
+It would still close support for all theese:
+- Intel i586 (all)
+- Some Intel Pentium D
+- AMD Geode < NX
+- VIA C3 (Samuel* and Ezra)
+- Transmeta Crusoe
+
+So, still not an option.
+
+
+And then to point out some other facts:
+
+Some of the benefits are already accounted for like you noted earlier:
+"Of course we shouldn't forget that the MDV had already a system for 
+providing optimized (look at /usr/lib/sse2 for instance) version of 
+libraries according to instruction set supported."
+
+And many applications capable of utilizing sse2 and other instruction 
+sets already have runtime detection support, so no problem there.
+
+
+So, where does that leave us?
+
+Simple.
+For 32bit installs, we will still support i586 as base.
+For 64bit installs, it's simple as x86_64 is SSE2 by default.
+
+
+Now, _if_ the Mageia community gets enough developers to think of _and_ 
+support a "light netbook/legacy edition", then maybe we can think of 
+doing a i586/i686 split, but for now we will use i586 as base.
+
+
+And many of the users wanting i686/sse2 already have hardware capable of 
+running x86_64, so that's what they should do, as there is where the 
+future is.
+
+--
+Thomas
+