[arch-dev-public] i686 and SSE2

[Allan McRae]

This goes beyond just adding SSE2 support.

Years ago, Arch Linux was "optimised for modern processors".  These were
the days when every other distro was using i386 and we had a blazingly
fast i686 port.  Now every other distro uses i686 while we have sat
still.  Even major software developments are starting to require SSE2.
It is time we moved forward.

How can we achieve this?  I see several options:

1) Do "nothing".  Add a hook to the filesystem package that detects
whether a system has SSE2 support and blocks installation of certain
packages.

2) Add SSE2 to our optimisations and require "i686 + SSE2"

3) Move our minimum CPU to something less than 20 years old  (even i786
would get us SSE2+3 instructions and is 15 years old)

4) We add more modern CPU builds  (and set them automatically building
once the base architecture is updated).


I am in favour of #3 for our 32-bit support.  And that would be end of
line as far as 32 bit support in this distribution goes.


(We may want to consider #4 for our x86_64, but that is another
conversation).

Allan