Re: [Qemu-devel] SMB for DOS ?

[John R. Hogerhuis]

On Sat, 2004-12-18 at 10:32, Paul Brook wrote:
> > > I hope you will not forget us poor mac users. Optimizing x86 on ppc
> > > performance would make a number of people very happy, I'd say.
> >
> > performance on ppc can become very good because
> > there are much more registers available for emulating
> > the x86 stuff ...
> 
> The really slow bit tends to be MMU emulation, and more host registers 
> doesn't 
> help here. Mapping all guest registers directly onto host registers probably 
> doesn't make all that much difference as the values will tend to be in L1 
> cache anyway.
> 
> Paul
> 

This raises an interesting question in my mind, given the existence of
"reconfigurable computing" where you have a PCI card containing an FPGA
loaded onto your machine (such things do exist, and I expect in the
future to start seeing these things standard on motherboards). Certainly
an MMU can be created in FPGA code. There is an interesting article on
reconfigurable computing in this month's Linux Journal, btw.

What kinds of generic hardware based support would really speed up
emulation of other CPUs? Of course, one could also ask the question of
what would be an ideal CPU instruction set for emulating other CPUs. But
if one narrowed the focus to things that could be accomplished by an
FPGA hooked to the bus, it could actually be implemented by anyone with
the interest to do it, whereas making a new CPU is an expensive
undertaking.

Might be an interesting project for a graduate student.

-- John.