Re: [Qemu-devel] Removal of some target CPU macros

[Paul Brook <paul@nowt.org>]

On Wednesday 07 November 2007, Bernhard Fischer wrote:
> On Wed, Nov 07, 2007 at 11:55:26PM +0100, Fabrice Bellard wrote:
> >Why not adding a new CPU type such as "PPC970 with hypervisor" and keep
> >the current PPC970 implementation as it is without the hypervisor mode.
> >I don't see the problem in replacing the ifdefs with a new CPU model !
> >You cannot reasonnably tell that it is uglier than the current code.
>
> IMHO same for i386sx. Without an FPU there is just no FPU. Without
> 486-specific instructions (or i586 etc. for that matter), the machine is
> just constrained to the one requested by the user.
>
> The fact that usually too many non ISA-imposed features are available
> without explicit user choice is very, very unfortunate, IMO.
> As always, features are or may be nice, iff and only if you are not
> forced to have or use them..

The i386 emulation always enables all features because noone's bothered to 
teach it which ones are optional.

I have local ARM patches (hopefully will be merged into CVS soon) that 
implement 5+ different ISA variants, 3 different FPUs, a SIMD vector unit and 
2 completely different exception models. All in the same binary, and all of 
which can be turned off if for emulating cpus that don't implement a 
particular feature.

Paul