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