Features/ArchitectureSupport - changing what we build for

[Bill Nottingham]

Toshio Kuratomi (a.badger at gmail.com) said: 
> >> * 32-bit x86 would be built for i686 by default. 586-compatible processors
> >> would no longer be supported.  
> > [...]
> >> * i386: -march=i586 -mtune=generic 
> > 
> > Should the latter be -march=i686?
> > 
> I was wondering this too but in the opposite direction -- why build
> everything for i686 by default if we're only updating the compiler flags
> to i586?
> 
> Jakub's email sparking this Feature listed the major benefit from
> getting new instructions with -march=i486.  He then listed additional
> helpful instructions when using -march=i586.  Nothing listed for
> -march=i686.

The idea is that RPMs are built for i686, ergo, they will get
-march=i686 explicitly passed to the compiler. The default compiler
flags for 32-bit will be -march=i586, which will allow people to
build i586-compatible code if they so desire.

Bill