Re: [Qemu-devel] [PATCH 3/9] powerpc/kvm: Enable mpic for E500 platform

[Aurelien Jarno]

On Fri, Jan 16, 2009 at 12:17:40PM -0600, Hollis Blanchard wrote:
> On Fri, 2009-01-16 at 13:34 +0800, Liu Yu wrote:
> > 
> > > -----Original Message-----
> > > From: Anthony Liguori [mailto:address@hidden 
> > > Sent: Friday, January 16, 2009 5:23 AM
> > > To: address@hidden
> > > Cc: Liu Yu-B13201; address@hidden
> > > Subject: Re: [Qemu-devel] [PATCH 3/9] powerpc/kvm: Enable 
> > > mpic for E500 platform
> > > 
> > > Liu Yu wrote:
> > > > The modify is based on original author's method
> > > > to switch openpic and mpic by static define,
> > > > like the switch between USE_INTEL_GW80314 and USE_MPCxxx.
> > > > (Although the support for intel has broken)
> > > > So they can't be used at the same time.
> > > >
> > > > I guess it's not the correct way to do this.
> > > > but I am not sure is the USE_MPC85xx and openpic are still needed?
> > > >   
> > > 
> > > Have you tested some of the other (TCG) boards (for instance, 
> > > with the 
> > > debian image Aurelien recently posted)?
> > > 

This image is only for g3beige, it won't work on mac99 which is moreover
broken.

> > You mean test powerpc mac99? No.
> 
> It doesn't sound like mac99 works right now anyways, so that may not be
> possible to test.

Confirmed. We hope to get it working in the next few weeks/months using
OpenBIOS, the same way as for the g3beige machine.

> > I only modified few places to the original code. I think it won't be 
> > influenced.
> > But mpic and openpic couldnot work in the same qemu binary with this patch.
> > If they should both be supported, then I need to modify more.
> 
> Due to the (artificial) "ppc" vs "ppcemb" split, I'm not sure this is a
> requirement.

Agreed. I am fine with some changes if they are only done for the ppcemb
binary.

> The only issue I can see is if there are "ppc" targets (e.g. 970) that
> use the same[1] MPIC as found on e500, and that is different from and
> not supported by the current OpenPIC emulation.

The person adding support for those "ppc" targets, will have to modify
the code to support both versions at runtime.

> [1] By "same" I mean "substantially similar". As I understand it,
> OpenPIC and MPIC are very similar designs, but there are different
> bugs/quirks to different implementations. So even if e500's MPIC isn't
> *exactly* the same as 970 chipsets' MPIC, if they're close enough that
> the code could be shared, it should be.
> 
> -- 
> Hollis Blanchard
> IBM Linux Technology Center
> 
> 
> 
> 

-- 
  .''`.  Aurelien Jarno             | GPG: 1024D/F1BCDB73
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