Re: [Qemu-devel] [PATCH]: add leon target

[Tristan Gingold]

On Jan 7, 2009, at 6:03 PM, Blue Swirl wrote:

> On 1/7/09, Tristan Gingold <address@hidden> wrote:
> > Hi,
> >
> > this patch adds a new target: leon which is an open source sparc v8  
> > variant.
>
> Thanks for the patch. Is there any way to test the system, rom images
> etc? Any system level docs?

I can send an image if you need one.  I can also send the sources but  
I suppose it would be useless to you
as this is Ada code.

For docs, see:
http://www.atmel.com/dyn/products/product_card.asp?part_id=3178

or www.gaisler.com

(Don't forget leon is open-source.  You can get VHDL files if you need).

> Do you think it would be useful to port OpenBIOS to the system?

Usually this chip is used in space engine: no disk and no ethernet.  I  
doubt OpenBIOS would be useful.
Gaisler Research provides a monitor but I didn't test it on qemu (and  
I am not sure it is freely available).
Also there is a port of Linux.  I once made it running on qemu (maybe  
4 years ago).  It should be the
easiest way to test the system.

> > The cpu itself implements the v8 architecture so there is nothing  
> > to change.
> > However the devices are different and in particular the interrupt  
> > controller.
> >
> > To handle different interrupt controllers, I added a new field in
> > CPUSPARCState like it is done on PowerPC.
>
> I have a feeling that this should be handled some other way but I
> don't know how yet. CPU emulation should not know about boards.

I have the same feeling too.  I am ready to improve the code but I  
need a few advices.
As currently implemented CPU emulation know about interrupt  
controller.  Wether interrupt controller
belongs to CPU or to the board is an open question :-)
Do you simply prefer to have hooks in CPUSPARCState ?

The same question applies to the MMU.  Most of early SPARC models do  
not have an integrated MMU.
Leon2 MMU is optional too.

> > Comments are welcome,
> > Tristan.
>
> Maybe the leon.c should be split, each device in a separate file.
> Though I guess the devices are so unique that they won't be used
> elsewhere.

Yes, they are so unique that it would create a lot of small files.  I  
am not sure we want to go that way.

> > +
> > +    switch (env->intctl) {
> > +    case intctl_sun4c:
> > +    case intctl_sun4m:
> > +#if !defined(CONFIG_USER_ONLY)
> > +      cpu_check_irqs(env);
> > +#endif
> > +      break;
> > +    case intctl_leon2:
> > +      if ((intno & ~15) == TT_EXTINT)
> > +       leon2_intctl_ack (env, intno);
>
> This breaks linux-user compilation, the whole switch should be  
> enclosed in
> #if !defined(CONFIG_USER_ONLY)
> #endif

Oops, sorry.  I will fix that.

> For extra bonus, you could implement the following:
> - register device reset methods
> - savevm/loadvm support
> - pic_info, irq_info support

Ok.

Tristan.