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

[Tristan Gingold]

> >

Hi,


> > 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 ?
>
> From my experience, interrupt controllers are usually not considered  
> to
> be part of the CPU.

(What about LAPIC/LSAPIC ?)

> Regarding the leon interrupt controller, I had a quick look at the  
> vhdl and
> AFAICT there is no need for any special tricks in the sparc cpu model.
> What you need is to handle accesses to the interrupt clear register,  
> in your
> code you seem to call it ITC and your io_writel does not handle it.
> This is the place to hook in calls to mask off bits from the pending
> interrupt reg.
>
> Your leon software should be writing to this register when acking
> interrupts.

No.  You have missed (p19):

When the IU acknowledges the interrupt, the corresponding pending bit  
will
automatically be cleared.

This is the only reason why the CPU must inform the interrupt  
controller.

> What you are doing know is providing a magic automatic ACK from the  
> core as
> soon as the interrupt is taken, IIUC this is not what leon does.

It is ;-)

> IMO you should be splitting the different blocks into separate files  
> as
> already suggested. You should also register separate IO regions for  
> every
> block. This is important in order to be able to reuse the blocks
> for different leon based socs/boards that may have different memory  
> maps.

Ok.

Tristan.