[Open-graphics] from the simulation front - bochs and system simulation

[Nicolas Boulay]

Be carefull with system wide simulation.

Bochs or qemu are near real speed software. around ~50% of the pc
speed, which is a real performance. A VHDL simulation are often 100
000 times slower than reality.

If you connect bochs to the OGD HDL code, you could wait hours before
the startup code ends.

If you want to write drivers, i think that we should use the software
model with the simplify PCI model of bochs. Then you only need one
more thin software layer for the real code to handle on real hardware.

So you could write 98% of the drivers and test it at near full speed.

Then you could extract the interraction with the pci bus model and use
it as test vector for testing the HDL code. The software model are
then used as "golden model".

2006/10/13, Attila Kinali <attila at kinali.ch>:
> Moin,
>
> I finaly had time to finish my check up of bochs.
> Unfortunately, the result is that we may not be
> able to use bochs for a system level simulation
> including the operating system. Bochs uses a
> too abstract model of the PCI bus (basicaly just
> read and write of arbitrary size data), so that we
> would need to rewrite quite some bit of bochs
> to extract those signals (or add a huge layer
> between bochs and our simulation). Synchronisation
> of both would be a whole other issue, which i
> didnt check.
>
> Currently i suggest either to stick with a pure
> functional verification in verilog and driver
> development using OGD1 or to write a low level
> PC simulator in a HDL.
>
> I could start one in VHDL, but with that we
> would have difficulties to interface it with
> verilog (or does someone have a OSS simulator
> capable of doing vhdl/verilog co-simulation?).
> Or someone could start one writing in verilog
> while i learn verilog myself. Well.. actually
> it doesn't really matter as the work in writting
> a full blown PC simulator, even a simplified
> one is a lot more work than writing a graphics
> card. Which in turn would make it more feasible
> to rewrite bochs in a way to fit our needs.
>
>                         Attila Kinali
>
> --
> egp ist vergleichbar mit einem ikea bausatz fuer flugzeugtraeger
>                         -- reeler in +kaosu
> _______________________________________________
> Open-graphics mailing list
> Open-graphics at duskglow.com
> http://lists.duskglow.com/mailman/listinfo/open-graphics
> List service provided by Duskglow Consulting, LLC (www.duskglow.com)
>